IEEE Recommended Practice for Electrical Installations on Shipboard--Design

IEEE Recommended Practice for Electrical Installations on Shipboard— Design

IEEE Industry Applications Society

Sponsored by the Petroleum & Chemical Industry Committee

IEEE 3 Park Avenue New York, NY 10016-5997 USA

IEEE Std 45.1™-2017

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IEEE Std 45.1™-2017

IEEE Recommended Practice for Electrical Installations on Shipboard— Design Sponsor

Petroleum & Chemical Industry Committee of the

IEEE Industry Applications Society Approved 23 March 2017

IEEE-SA Standards Board

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Abstract: Recommendations for the design of electrical power generation, distribution, propulsion, loads systems, and equipment on merchant, commercial, and naval vessels are covered in this document.

Keywords: IEEE 45.1™, marine electrical engineering, marine vessels, navel vessels, ship, shipboard electrical systems •

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Participants At the time this IEEE recommended practice was completed, the P45.1 Working Group had the following membership: Dwight Alexander, Chair Robert Koebke, Vice Chair Timothy L. Gauthier, Secretary Moni Islam, Past Chair

Mohammed Ahmed John Amy Paul Bishop†Charlie Butcher William Byrd John Cadick Corey Cahill Lee Carabeo Angela Card Don Chambers Carl Chowaniec Vincent DelGatto Norbert Doerry Mike Drew Kamal Garg

Lukas Graber Torsten Gruhn Bill Hayden Chris Heron Anthony Hoevenaars Akhter Hossain Paul Kelly Yuri Khersonsky Stephen Ly Earl MacDonald Nicole Maillette Tim McCoy John Merando Daryl Moore Dennis Neitzel Mark Nelson

Robert Olmstead Sergio Panetta Kevin Peterson Joseph Piff Mike Roa Gary Savage Thomas Schubert Robert Seitz Gary Skibinski Mischa Steurer James Turso Don Voltz David Wallace Vicki Warren James Waters James Wolfe

The following members of the individual balloting committee voted on this recommended practice.

Balloters may have voted for approval, disapproval, or abstention.

David Aho Dwight Alexander Saleman Alibhay John Amy Ettore Bartolucci Frank Basciano Michael Basler Paul Becker Gustavo Brunello William Bush William Byrd Paul Cardinal Matthew Davis Davide De Luca Norbert Doerry Neal Dowling Robert Durham Timothy L. Gauthier Mietek Glinkowski Jalal Gohari J Travis Griffith Randall Groves Chris Heron Lee Herron

Werner Hoelzl Anthony Hoevenaars John Houdek Richard Jackson Ben C Johnson Piotr Karocki John Kay Paul Kelly Yuri Khersonsky Robert Koebke Michael Lauxman George Cristian Lazaroiu Wei-Jen Lee Steven Liggio Earl MacDonald Arturo Maldonado John Malinowski William McBride Dennis Neitzel Arthur Neubauer T. W. Olsen Lorraine Padden Richard Paes Sergio Panetta

Kevin Peterson K. James Phillips Joseph Piff Iulian Profir Ryandi Ryandi Daniel Sabin Gary Savage Bartien Sayogo Thomas Schubert Robert Seitz Nikunj Shah Xu She Jerry Smith Gary Smullin Michael Steurer James Timperley Albert Tucker John Turner Demetrios Tziouvaras James Van De Ligt John Vergis Daniel Ward Kenneth White Jian Yu

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When the IEEE-SA Standards Board approved this recommended practice on 23 March 2017, it had the following membership:

Jean-Philippe Faure, Chair Gary Hoffman, Vice Chair John D. Kulick, Past Chair Konstantinos Karachalios, Secretary Chuck Adams Masayuki Ariyoshi Ted Burse Stephen Dukes Doug Edwards J. Travis Griffith Michael Janezic

Thomas Koshy Joseph L. Koepfinger* Kevin Lu Daleep Mohla Damir Novosel Ronald C. Petersen Annette D. Reilly

Robby Robson Dorothy Stanley Adrian Stephens Mehmet Ulema Phil Wennblom Howard Wolfman Yu Yuan

*Member Emeritus

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Introduction This introduction is not part of IEEE Std 45.1-2017, IEEE Recommended Practice for Electrical Installations on Shipboard—Design.

The IEEE Std 45 series comprises nine recommended practices addressing electrical installations on ships and marine platforms. IEEE Std 45.1 provides recommended practice for design recommendations for ac power systems, dc power systems, emergency power systems, shore power, power quality and harmonics, electric propulsion and maneuvering systems, motors and drives, thrusters, and steering systems installed shipboard and is intended for use with the IEEE Std 45 series of documents. The topics covered in this document should be considered from the beginning of the project and throughout the design and construction processes, and thereby should facilitate the integration of electrical systems at the shipyard level. Adherence to the IEEE 45.1 design process provides an effective set of integration requirements and identifies key issues and recommended solutions or options.

Previous editions of IEEE Std 45 were developed as single documents addressing all areas. On 9 June 2005, PAR 45 for the Revision of IEEE Std 45-2002 was approved and the revision of IEEE Std 45 as a single document began. It soon became apparent that attempting to cover all issues in a single document would produce a document that was very large and, therefore, difficult to ballot due to the wide range of issues needing to be addressed. In September 2008 it was decided that the revision of IEEE Std 45 should be developed as a base document with separate documents addressing specific areas.

On 10 December 2008 separate Project Authorization Requests (PARs) were approved for seven separate recommended practices. Additional PARs were approved on 11 September 2009 for Switchboards and 9 December 2009 for Cable Systems bringing the total number of standards in the IEEE Std 45 series to nine, including: 

IEEE Std 45™, IEEE Recommended Practice for Electrical Installations on Shipboard



IEEE Std 45.1™-2016, IEEE Recommended Practice for Electrical Installations on Shipboard— Design



IEEE Std 45.2™-2011, IEEE Recommended Practice for Electrical Installations on Shipboard— Controls and Automation



IEEE Std 45.3™-2015, IEEE Recommended Practice for Shipboard Electrical Installations— Systems Engineering



IEEE P45.4™, Recommended Practice for Electrical Installations on Shipboard—Marine Sectors and Mission Systems



IEEE Std 45.5™-2014, IEEE Recommended Practice for Electrical Installations on Shipboard— Safety Considerations



IEEE Std 45.6™-2016, IEEE Recommended Practice for Electrical Installations on Shipboard— Electrical Testing



IEEE Std 45.7™-2012, IEEE Recommended Practice for Electrical Installations on Shipboard—AC Switchboards



IEEE Std 45.8™-2016, IEEE Recommended Practice for Electrical Installations on Shipboard— Cable Systems

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Contents 1. Overview .................................................................................................................................................. 14 1.1 Introduction ....................................................................................................................................... 14 1.2 Scope ................................................................................................................................................. 14 1.3 Purpose .............................................................................................................................................. 15 1.4 Application of various national and international standards .............................................................. 15 1.5 Equipment construction, testing, and certification............................................................................. 15 2. Normative references................................................................................................................................ 15 3. Definitions, acronyms, and abbreviations ................................................................................................ 19 3.1 Definitions ......................................................................................................................................... 19 3.2 Acronyms and abbreviations ............................................................................................................. 24 4. System engineering .................................................................................................................................. 25 4.1 Introduction ....................................................................................................................................... 25 4.2 Design baseline .................................................................................................................................. 26 4.3 Product design ................................................................................................................................... 27 4.4 Product baseline ................................................................................................................................. 27 5. Power system characteristics .................................................................................................................... 28 5.1 Electrical power systems architectures .............................................................................................. 28 5.2 Standard systems ............................................................................................................................... 30 5.3 Standard voltage ................................................................................................................................ 30 5.4 Standard frequency ............................................................................................................................ 31 5.5 Selection of voltage and system type ................................................................................................. 31 5.6 AC power system characteristics ....................................................................................................... 32 5.7 DC power systems characteristics ..................................................................................................... 34 5.8 Key electrical power system design inputs ........................................................................................ 35 5.9 Quality of service (QoS) .................................................................................................................... 35 5.10 Electrical power system concept of operation (EPS-CONOPS) ...................................................... 37 5.11 Marine environmental conditions .................................................................................................... 38 6. Electrical power system elements ............................................................................................................. 39 6.1 Introduction ....................................................................................................................................... 39 6.2 Power generation ............................................................................................................................... 39 6.3 Power distribution.............................................................................................................................. 39 6.4 Power conversion .............................................................................................................................. 41 6.5 Energy storage ................................................................................................................................... 41 6.6 Electrical power system supervisory control ..................................................................................... 41 6.7 Loads ................................................................................................................................................. 42 7. Power system design ................................................................................................................................ 43 7.1 Power generation and energy storage capacities................................................................................ 43 7.2 Power conversion and transformer ratings ........................................................................................ 44 7.3 Emergency power .............................................................................................................................. 45 7.4 Safety ................................................................................................................................................. 50 7.5 Power quality and harmonics............................................................................................................. 50 8. Electrical power generation ...................................................................................................................... 51 8.1 General .............................................................................................................................................. 51 8.2 Installation and location..................................................................................................................... 51 9 Copyright Š 2017 IEEE. All rights reserved.

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8.3 Generator set prime movers ............................................................................................................... 52 8.4 Generators.......................................................................................................................................... 58 9. Power distribution .................................................................................................................................... 64 9.1 General .............................................................................................................................................. 64 9.2 Circuit elements ................................................................................................................................. 64 9.3 Shore power ....................................................................................................................................... 65 9.4 Demand factors .................................................................................................................................. 65 9.5 Voltage drop ...................................................................................................................................... 66 9.6 Lighting distribution .......................................................................................................................... 67 9.7 Delivery power feeders ...................................................................................................................... 68 9.8 Branch circuits ................................................................................................................................... 68 9.9 Circuit designation ............................................................................................................................. 70 9.10 Distribution equipment .................................................................................................................... 73 10. Power conversion ................................................................................................................................... 81 10.1 Power electronics ............................................................................................................................. 81 10.2 Transformers/reactors ...................................................................................................................... 82 11. Energy storage ........................................................................................................................................ 84 11.1 General ............................................................................................................................................ 84 11.2 Specific applications ........................................................................................................................ 84 11.3 Rechargeable storage batteries......................................................................................................... 85 12. Electrical power system control.............................................................................................................. 96 12.1 Supervisory control interfaces ......................................................................................................... 96 12.2 Control system connectivity ............................................................................................................ 96 12.3 Application layer protocol ............................................................................................................... 97 12.4 Sources and loads ............................................................................................................................ 98 12.5 Voice communication systems ........................................................................................................ 99 13. Motor and motor application .................................................................................................................. 99 13.1 General application .......................................................................................................................... 99 13.2 AC and DC motors—general..........................................................................................................100 13.3 Selection .........................................................................................................................................100 13.4 Installation and location ..................................................................................................................101 13.5 Insulation of windings ....................................................................................................................101 13.6 Locked rotor kVA ...........................................................................................................................102 13.7 Efficiency .......................................................................................................................................102 13.8 Lubrication .....................................................................................................................................102 13.9 Terminal arrangements ...................................................................................................................102 13.10 Corrosion-resistance parts ............................................................................................................103 13.11 Nameplates ...................................................................................................................................103 13.12 Ambient temperature ....................................................................................................................103 13.13 Limits of temperature rise .............................................................................................................103 13.14 Motor application .........................................................................................................................104 13.15 Duty rating ....................................................................................................................................106 13.16 Steering gear motors .....................................................................................................................106 13.17 Motor brakes .................................................................................................................................107 13.18 Magnetic friction clutches ............................................................................................................109 14. Adjustable speed drive (ASD) applications ...........................................................................................110 15. Electric propulsion and maneuvering system ........................................................................................110 15.1 Scope ..............................................................................................................................................110 15.2 Regulations .....................................................................................................................................111 10 Copyright Š 2017 IEEE. All rights reserved.

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15.3 System requirements .......................................................................................................................111 15.4 Prime movers for integrated power and propulsion plants .............................................................113 15.5 Generators for integrated power and propulsion plants ..................................................................114 15.6 Propulsion drive transformers .........................................................................................................115 15.7 Propulsion motors ...........................................................................................................................117 15.8 Propulsion power conversion equipment ........................................................................................119 15.9 Main power switchboard ................................................................................................................120 15.10 Propulsion control equipment .......................................................................................................121 15.11 Power management.......................................................................................................................123 15.12 Podded propulsion ........................................................................................................................123 15.13 Propulsion cables ..........................................................................................................................124 15.14 Propulsion equipment location .....................................................................................................125 15.15 Ventilation ....................................................................................................................................125 15.16 Bed-plates and foundations...........................................................................................................125 15.17 Lubrication....................................................................................................................................125 15.18 Fire extinguishers .........................................................................................................................126 16. Steering systems ....................................................................................................................................126 16.1 General ...........................................................................................................................................126 16.2 Navigating bridge installation.........................................................................................................126 16.3 Power supply ..................................................................................................................................127 16.4 Alarm system ..................................................................................................................................127 16.5 Steering gear ...................................................................................................................................127 16.6 Steering control systems .................................................................................................................128 17. Lighting equipment ...............................................................................................................................130 17.1 General ...........................................................................................................................................130 17.2 Location ..........................................................................................................................................131 17.3 Provisions for portable lighting ......................................................................................................131 17.4 Permanent watertight fixtures .........................................................................................................132 17.5 Permanent non-watertight fixtures..................................................................................................132 17.6 High-intensity discharge lamp fixtures ...........................................................................................132 17.7 Lighting for hazardous locations ....................................................................................................132 17.8 Illumination ....................................................................................................................................132 17.9 Searchlights ....................................................................................................................................133 17.10 Emergency lighting.......................................................................................................................134 17.11 Nameplates ...................................................................................................................................134 17.12 Solid state lighting (SSL)..............................................................................................................134 17.13 Navigation lights and signal lights................................................................................................136 18. Whistle and siren control systems .........................................................................................................137 19. Heating equipment.................................................................................................................................138 19.1 Construction....................................................................................................................................138 19.2 Heating elements ............................................................................................................................138 19.3 Control switches .............................................................................................................................139 19.4 Temperature ....................................................................................................................................139 19.5 Nameplates .....................................................................................................................................139 19.6 Electrical heat trace (EHT) .............................................................................................................139 20. Galley equipment and workshop equipment .........................................................................................140 20.1 Electric cooking equipment ............................................................................................................140 20.2 Motor-driven equipment .................................................................................................................143 20.3 Nameplates .....................................................................................................................................144 21. Electrical power system protection ........................................................................................................144 11 Copyright Š 2017 IEEE. All rights reserved.

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21.1 Overview ........................................................................................................................................144 21.2 Electrical power system protection elements ..................................................................................144 21.3 Electrical power system protection design .....................................................................................145 22. System studies, analyses, and reports ....................................................................................................148 22.1 General ...........................................................................................................................................148 22.2 Electric plant load analysis (EPLA)................................................................................................149 22.3 Load flow analysis and voltage drop analysis ................................................................................149 22.4 Dynamic analysis (transient and stability) ......................................................................................150 22.5 Fault current analysis ......................................................................................................................152 22.6 Harmonic and frequency analysis ...................................................................................................153 22.7 Failure mode and effects analysis (FMEA) ....................................................................................157 22.8 Electromagnetic interference (EMI) analysis .................................................................................157 22.9 Thermal analysis .............................................................................................................................157 22.10 Electrical power system data for the life-cycle cost analysis ........................................................157 22.11 Electrical power system data for the signature analysis................................................................158 22.12 Safe return to port/survivability analysis ......................................................................................158 22.13 Future power growth assessment ..................................................................................................158 22.14 Protective device coordination study ............................................................................................158 22.15 Grounding system design report ...................................................................................................159 22.16 Electrical power system corrosion control report .........................................................................159 22.17 Electrical power system input to ship’s weight report ..................................................................159 22.18 Electrical power system section of the master equipment list ......................................................159 22.19 Electrical power system input to endurance fuel calculations ......................................................159 22.20 Incident energy analysis ...............................................................................................................159 23. EMI/EMC/RFI.......................................................................................................................................160 24. Materials ................................................................................................................................................160 24.1 Corrosion-resistant parts .................................................................................................................160 24.2 Flame-retardant materials ...............................................................................................................160 24.3 Brittle material ................................................................................................................................161 24.4 Cable selection, application, and installation ..................................................................................161 25. Power system grounding (earthing) .......................................................................................................161 25.1 General ...........................................................................................................................................161 25.2 Power system grounding.................................................................................................................161 25.3 Point of system grounding ..............................................................................................................163 25.4 Equipment grounding .....................................................................................................................163 25.5 Ground plates on nonmetallic ships ................................................................................................164 25.6 Lightning protection grounding ......................................................................................................165 25.7 Stray current protection ..................................................................................................................165 25.8 Ground-fault detection ....................................................................................................................165 26. Arc flash management ...........................................................................................................................166 27. Hazardous locations, installations, and equipment ................................................................................169 27.1 General ...........................................................................................................................................169 27.2 Hazardous area classification..........................................................................................................169 27.3 Area classification for various vessel types ....................................................................................174 27.4 Hazardous locations equipment protection techniques ...................................................................177 27.5 Hazardous locations equipment markings ......................................................................................181 27.6 Approved equipment ......................................................................................................................182 27.7 Equipment Installation ....................................................................................................................183 28. Ship construction and outfitting ............................................................................................................185 12 Copyright Š 2017 IEEE. All rights reserved.

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28.1 Storage and installation...................................................................................................................185 28.2 Spare parts ......................................................................................................................................186 28.3 Documentation................................................................................................................................186 29. System operation and maintenance .......................................................................................................186 29.1 Fire extinguishing precautions ........................................................................................................186 29.2 Rotating machine cleanliness..........................................................................................................186 29.3 Care of idle apparatus .....................................................................................................................187 29.4 Safety ..............................................................................................................................................187 Annex A (informative) Bibliography ..........................................................................................................188 Annex B (normative) Electric plant load analysis .......................................................................................189

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IEEE Recommended Practice for Electrical Installations on Shipboard— Design

1. Overview 1.1 Introduction These recommendations establish the minimally acceptable guidelines for the design, selection, and installation of systems and equipment aboard both Navy combatant and commercial marine vessels applying electrical apparatus for power, propulsion, steering, automation, navigation, lighting, and communications. These recommendations describe present-day acceptable marine electrical engineering methods and practices. The primary focus of these IEEE Std 45.1 guidelines is overall electrical power system and subsystem design. Guidelines for some key electrical power system components (including electrical power switchboards, cable systems, and control systems), safety considerations, and system testing are discussed elsewhere in this IEEE Std 45™ series, which comprises nine recommended practices addressing electrical installations on ships and marine platforms.

It is recognized that changes and improvements in shipboard requirements may develop that are not specifically covered herein; such changes, if incorporated in the design, should be equal to the safety and reliability levels established herein and generally in accord with the intent of these standards.

In developing these recommendations, consideration was given to the electrical and engineering requirements promulgated by various regulatory agencies, classification societies, and by the International Maritime Organization’s International Convention for the Safety of Life at Sea (IMO SOLAS), as amended.

This recommended practice was developed by a voluntary consensus body to provide assistance and guidance to regulatory agencies governing electrical engineering requirements.

1.2 Scope The recommendations for electrical power generation, distribution, and electric propulsion system design for use on shipboard are established by this document. These recommendations reflect the present-day technologies, engineering methods, and engineering practices.

This document is intended to be used in conjunction with the IEEE Std 45 series.

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IEEE Std 45.1-2017 IEEE Recommended Practice for Electrical Installations on Shipboard—Design

1.3 Purpose The main purpose of this recommended practice is to provide a consensus of recommended design practices in the unique field of marine electrical engineering as applied specifically to ships, shipboard systems, and equipment.

1.4 Application of various national and international standards It is recognized that various national and international standards for equipment and installations are not identical. However, it is recognized that mixing of standards is occasionally necessary. Therefore, the application of any of these standards is the choice of the user, authority having jurisdiction, and classification society.

Special precautions must be exercised when mixing equipment designed to different national and international standards. Coordination of different equipment design and testing standards, construction ratings, installation methods, and performance must be carefully analyzed.

1.5 Equipment construction, testing, and certification Electrical apparatus and equipment should be constructed and tested in accordance with the requirements of appropriate national and international equipment standards. Standards specifically addressing marine requirements should be used whenever applicable. Many appropriate standards are referenced in this document. All electrical equipment should be tested and certified, with labeling and follow-up services (i.e., listed) by a recognized independent laboratory acceptable to the authority having jurisdiction.

2. Normative references The following referenced documents are indispensable for the application of this document (i.e., they must be understood and used, so each referenced document is cited in text and its relationship to this document is explained). For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments or corrigenda) applies.

ANSI C63.12™, American National Standard Recommended Practice for Electromagnetic Compatibility Limits and Test Levels. 1 ANSI/EIA 709, Control Network Protocol Specification. 2 ANSI/ISA 60079-0, Explosive Atmospheres–Part 0: Equipment–General Requirements.

ANSI/NEMA MG 1, Motors and Generators. 3 API RP 14F, Design, Installation, and Maintenance of Electrical Systems for Fixed and Floating Offshore Petroleum Facilities for Unclassified and Class I, Division 1 and Division 2 Locations. 4 ANSI publications are available from the American National Standards Institute (http://www.ansi.org/).

EIA publications are available from the U.S. Energy Information Administration (http://www.eia.gov/).

3 NEMA publications are available from the National Electrical Manufacturers Association (http://www.nema.org/).

4 API publications are available from the Publications Section, American Petroleum Institute, 1200 L Street NW, Washington, DC 20005, USA (http://www.api.org/).

1 2

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API RP 14FZ, Recommended Practice for Design and Installation of Electrical Systems for Fixed and Floating Offshore Petroleum Facilities for Unclassified and Class 1, Zone 0, Zone 1 and Zone 2 Locations.

API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2.

API RP 505, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Zone 0, Zone 1, and Zone 2.

ASTM B117, Standard Practice for Operating Salt Spray (FOG) Apparatus. 5 ASTM D229, Standard Test Methods for Rigid Sheet and Plate Materials Used for Electrical Insulation.

ASTM F1003, Standard Specification for Searchlights on Motor Lifeboats.

ETSI EN 300 132-3-1, Environmental Engineering (EE); Power supply interface at the input to telecommunications and datacom (ICT) equipment; Part 3: Operated by rectified current source, alternating current source or direct current source up to 400 V; Sub-part 1: Direct current source up to 400 V. 6, 7 IACS UR M59, Control and Safety Systems for Dual Fuel Diesel Engines. 8 IEC 60034, Rotating electrical machinery. 9 IEC 60038, IEC standard voltages.

IEC 60076-1, Power transformers–Part 1: General.

IEC 60092 Series, Electrical installations in ships.

IEC 60146 Series, Semiconductor converters.

IEC 60726, Dry-type power transformers.

IEC 60947-6-1, Low voltage switchgear and controlgear–Part 6-1: Multiple function equipment–Transfer switching equipment.

IEC 61000 Series, Electromagnetic compatibility (EMC).

IEC/IEEE 60079-30-1, Explosive atmospheres–Part 30-1: Electrical resistance trace heating–General and testing requirements.

IEC/ISO/IEEE 80005-1, Utility connections in port–Part 1: High Voltage Shore Connection (HVSC) Systems–General requirements. 10 IEEE Std C50™ Series, Standards for large steam and combustion turbine generators. 11, 12 ASTM publications are available from the American Society for Testing and Materials (http://www.astm.org/).

ETSI publications are available from the European Telecommunications Standards Institute (http://www.etsi.org/).

7 EN publications are available from the European Committee for Standardization (CEN) (http://www.cen.eu/).

8 IACS publications are available from the International Association of Classification Societies Ltd. (http://www.iacs.org.uk/).

9 IEC publications are available from the International Electrotechnical Commission (http://www.iec.ch) and the American National Standards Institute (http://www.ansi.org/).

10 ISO publications are available from the International Organization for Standardization (http://www.iso.org/) and the American National Standards Institute (http://www.ansi.org/).

11 The IEEE standards or products referred are trademarks owned by the Institute of Electrical and Electronics Engineers, Incorporated.

5 6

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IEEE Std C57, Series on transformers.

IEEE Std C57.12.00™, IEEE Standard for General Requirements for Liquid-Immersed Distribution, Power, and Regulating Transformers.

IEEE Std C57.12.90™, IEEE Standard Test Code for Liquid-Immersed Distribution, Power, and Regulating Transformers.

IEEE Std 45.2, IEEE Recommended Practice for Electrical Installations on Shipboard—Controls and Automation.

IEEE Std 45.3, IEEE Recommended Practice for Shipboard Electrical Installations—Systems Engineering.

IEEE Std 45.5, IEEE Recommended Practice for Electrical Installations on Shipboard—Safety Considerations.

IEEE Std 45.7, IEEE Recommended Practice for Electrical Installations on Shipboard—AC Switchboards.

IEEE Std 45.8, IEEE Recommended Practice for Electrical Installations on Shipboard—Cable Systems.

IEEE Std 142, IEEE Recommended Practice for Grounding of Industrial and Commercial Power Systems.

IEEE Std 432, IEEE Guide for Insulation Maintenance for Rotating Electric Machinery (5 hp to less than 10 000 hp).

IEEE Std 444, Standard Practices and Requirements for Thyristor Converters for Motor Drives, Part 1Converters for DC Motor Armature Supplies.

IEEE Std 519, IEEE Recommended Practice and Requirements for Harmonic Control in Electrical Power Systems.

IEEE Std 802.3™, IEEE Standard for Ethernet.

IEEE Std 841, IEEE Standard for Petroleum and Chemical Industry−Premium-Efficiency, Severe-Duty Totally Enclosed Fan-Cooled (TEFC) Squirrel Cage Induction Motors−Up to and Including 370 kW (500 hp).

IEEE Std 1100, IEEE Recommended Practice for Powering and Grounding Electronic Equipment.

IEEE Std 1566, IEEE Standard for Performance of Adjustable-Speed AC Drives Rated 375 kW and Larger.

IEEE Std 1584, IEEE Guide for Performing Arc Flash Hazard Calculations.

IEEE Std 1662, IEEE Guide for the Design and Application of Power Electronics in Electrical Power Systems on Ships.

12

IEEE publications are available from the Institute of Electrical and Electronics Engineers (http://standards.ieee.org/).

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IEEE Std 45.1-2017 IEEE Recommended Practice for Electrical Installations on Shipboard—Design

IEEE Std 1709, IEEE Recommended Practice for 1 kV to 35 kV Medium-Voltage DC Power Systems on Ships.

IEEE Std 1815, IEEE Standard for Electric Power Systems Communications-Distributed Network Protocol (DNP3).

IEEE Std 1826, IEEE Standard for Power Electronics Open System Interfaces in Zonal Electrical Distribution Systems Rated Above 100 kW. IEEE Std 3003.2, IEEE Recommended Practice for Equipment Grounding and Bonding in Industrial and Commercial Power Systems.

IEEE Std 15288.1, IEEE Standard for Application of Systems Engineering on Defense Programs.

ISA TR12.24.01 (IEC 79-10 Mod), Recommended Practice for Classification of Locations for Electrical Installations Classified as Class I, Zone 0, Zone 1, or Zone 2. 13 MIL-STD-461E-1999, Department of Defense Interface Standard: Requirements for the Control of Electromagnetic Interference Characteristics of Subsystems and Equipment. 14 MIL-STD-704F, Department of Defense Interface Standard: Aircraft Electric Power Characteristics.

MIL-STD-1399-300B, Department of Defense Interface Standard: Section 300b, Electric Power, Alternating Current.

MIL-STD-1399-680, Department of Defense Interface Standard: Section 680, High Voltage Electric Power, Alternating Current.

NFPA 70, National Electrical Code® (NEC®). 15, 16 NFPA 70E, Standard for Electrical Safety in the Workplace.® NFPA 77, Recommended Practice on Static Electricity.

NFPA 780, Standard for the Installation of Lightning Protection Systems.

SOLAS Consolidated Edition, 1997, Consolidated text of the International Convention for the Safety of Life at Sea, 1974, and its Protocol of 1978: articles, annex and certificates: incorporating all amendments in effect from 1 July 1997. 17 UL 73, Standard for Safety Motor-Operated Appliances. 18 UL 153, Standard for Safety Portable Electric Luminaires.

UL 197, Standard for Safety Commercial Electric Cooking Appliances.

ISA publications are available from the International Society of Automation (http://www.isa.org/).

MIL publications are available from the U.S. Department of Defense (http://quicksearch.dla.mil/).

15 The NEC is published by the National Fire Protection Association (http://www.nfpa.org/). Copies are also available from the Institute of Electrical and Electronics Engineers (http://standards.ieee.org/).

16 NFPA publications are published by the National Fire Protection Association (http:// www.nfpa.org/).

17 SOLAS publications are available from the International Maritime Organization, 4 Albert Embankment, London SE1 7SR, United Kingdom.

18 UL publications are available from Underwriters Laboratories (http://www.ul.com/).

13 14

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UL 399, Standard for Safety Drinking-Water Coolers.

UL 471, Standard for Safety Commercial Refrigerators and Freezers.

UL 486A, Standard for Safety Wire Connectors and Soldering Lugs for Use with Copper Conductors.

UL 595, Standard for Safety Marine-Type Electric Lighting Fixtures.

UL 921, Standard for Safety Commercial Dishwashers.

UL 924, Standard for Safety Emergency Lighting and Power Equipment.

UL 1008, Standard for Safety Transfer Switch Equipment.

UL 1042, Standard for Safety Electric Baseboard Heating Equipment.

UL 1278, Standard for Safety Moveable and Wall- or Ceiling-Hung Electric Room Heaters.

UL 1570, Standard for Safety Fluorescent Lighting Fixtures. 19 UL 1571, Standard for Safety Incandescent Lighting Fixtures. 20 UL 1572, Standard for Safety High Intensity Discharge Lighting Fixtures. 21 UL 1598, Standard for Safety Luminaires.

UL 2021, Standard for Safety Fixed and Location-Dedicated Electric Room Heaters.

3. Definitions, acronyms, and abbreviations 3.1 Definitions For the purposes of this document, the following terms and definitions apply. The IEEE Standards Dictionary Online should be consulted for terms not defined in this clause. 22 accommodation spaces: Spaces provided for passengers and crew members that are used for berthing, dining rooms, mess spaces, offices, private baths, toilets and showers, lounges, and similar spaces. adjustable speed drive (ASD): A converter using controlled rectifier or transistor devices that has the capability of adjusting the frequency and proportional voltage of the output waveform to provide speed control of motors.

UL 1570-1995 has been withdrawn; however, copies can be obtained from Global Engineering, 15 Inverness Way East, Englewood, CO 80112-5704, USA, tel. (303) 792-2181 (http://global.ihs.com/).

20 UL 1571-1995 has been withdrawn; however, copies can be obtained from Global Engineering, 15 Inverness Way East, Englewood, CO 80112-5704, USA, tel. (303) 792-2181 (http://global.ihs.com/).

21 UL 1572-1995 has been withdrawn; however, copies can be obtained from Global Engineering, 15 Inverness Way East, Englewood, CO 80112-5704, USA, tel. (303) 792-2181 (http://global.ihs.com/).

22 IEEE Standards Dictionary Online is available at: http://dictionary.ieee.org 19

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adjustable-speed motor: A motor whose speed can be varied gradually over a range of speeds, but when once adjusted remains practically unaffected by the load, such as a dc shunt-wound motor with field resistance control designed for a range of speed adjustments. alternating current (ac): A periodic current with an average value over a period of time of zero. Unless distinctly specified otherwise, the term refers to a current that reverses at regularly recurring intervals of time and that has alternately positive and negative values. amortisseur winding: A permanently short-circuited winding used for inductively starting synchronous motors consisting of conductors embedded in the pole shoes of a synchronous machine and connected together at the ends of the poles, but not necessarily connected between poles. automatic bus transfer (ABT) system: Self-acting equipment for transferring one or more load conductor connections from one power source to another. auxiliary machinery space: Spaces containing ship-service or mission machinery, but located outside of the main machinery casing. base speed of an adjustable-speed motor: The lowest speed obtained at rated load and rated voltage at the specified temperature rise. breakdown torque: The maximum torque a motor will develop, with rated voltage applied at rated frequency, without an abrupt drop in speed. capacitance (capacity): That property of a system of conductors and dielectrics that permits the storage of electricity when potential differences exist between the conductors. Its value is expressed as the ratio of a quantity of electricity to a potential difference. A capacitance value is always positive. capacitor: A device with the primary purpose of introducing capacitance into an electric circuit. Capacitors are usually classified, according to their dielectrics, as air capacitors, mica capacitors, paper capacitors, and so on. cargo vessel: A vessel that carries bulk, containerized, or roll-on/roll-off dry cargo, and no more than 12 passengers. Research vessels, search and rescue vessels, and tugs are also considered to be cargo vessels in these recommendations. compound-wound motor: A dc motor that has two separate field windings: one, usually the predominating field, connected in parallel with the armature circuit, and the other connected in series with the armature circuit. Speed and torque characteristics are between those of shunt and series motors. continuous duty: A requirement of service that demands operation at a constant load for an indefinite period of time. cycle: The complete series of values of a periodic quantity that occurs during a period. It is one complete set of positive and negative values of an alternating current. direct current (dc): A unidirectional current in which the changes in value (polarity) are either zero or so small that they may be neglected. As ordinarily used, the term designates a practically non-pulsating current. duplex receptacle: Two electrical receptacles housed in the same outlet box. electric generator: A machine that transforms mechanical power into electric power. electric motor: A machine that transforms electric power into mechanical power.

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electronics: That branch of science and technology that relates to devices in which conduction is principally by electrons moving through a vacuum, gas, or semiconductor. enclosed self-ventilated: A machine that has openings for the ventilating air circulated by means integral with the machine, the machine being otherwise totally enclosed. These openings are so arranged that inlet and outlet ducts or pipes may be connected. exciter: The source of all or part of the field current for the excitation of an electric machine. frequency: The number of periods occurring in unit time of a periodic quantity, in which time is the independent variable. frequency converter: A converter using semiconductor devices to vary the output waveform and frequency to a motor as a means of controlling motor speed and or torque.

Hertz (Hz): The unit of frequency, one cycle per second. induction generator: An induction machine driven above synchronous speed by an external source of mechanical power. induction motor: A polyphase ac motor in which the secondary field current is created solely by induction.

The motor operates at less than synchronous speed and less than unity power factor. The operating speed is dependent on the frequency of the power source. It is generally the motor of choice for auxiliary drives. intermittent duty: A requirement of service that demands operation for alternate periods: load and no load, load and rest, or load, no load, and rest, as specified. lighters: Short-range cargo-transfer vessels or barges used for ferrying cargo or personnel. lug: A wire connector device to which the electrical conductor is attached by mechanical pressure or solder. machinery spaces: Spaces that are primarily used for machinery of any type, or equipment for the control of such machinery, such as boiler, engine, generator, motor, pump, and evaporator rooms. main machinery space: A space generally confined by the fireproof boundary of the machinery casing, and normally containing major ships’ equipment and prime moving equipment, including propulsion services equipment. manual bus transfer (MBT) switch: Non-self-acting equipment for transferring one or more load conductor connections from one power source to another. mobile offshore drilling units: Mobile platforms including self-elevating drilling units (SEDUs or jackups), column-stabilized drilling units (CSDUs) or semisubmersibles, and drillships. motor-generator set: A machine that consists of one or more motors mechanically coupled to one or more generators to convert electric power from one frequency to another, or to create an isolated power source. multi-cable penetrator: A device consisting of multiple nonmetallic cable seals assembled in a surrounding metal frame, for insertion in openings in decks, bulkheads, or equipment enclosures and through which cables may be passed to penetrate decks or bulkheads or to enter equipment without impairing their original fire or watertight integrity. passenger vessel: A vessel that carries more than 12 persons in addition to the crew.

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radar: A device that radiates electromagnetic waves and utilizes the reflection of such waves from distant objects to determine their existence or position. reactance: The imaginary component (± j, or ± 90° phase angle) of impedance, where resistance is the real component with a zero-phase angle. Reactance appears in two forms, one as a capacitive reactance ( X C ) for a capacitor ( C ), and the other as inductive reactance ( X L ) for an inductor ( L ). The former has the negative 90° phase angle, and the latter a positive 90° angle. Their values can be expressed in the following relationships: XC =

1 2π fC

and X L = 2π fL

where: f

is the excitation frequency

reactor: A device with the primary purpose of introducing reactance into an electric circuit for purposes such as motor starting, paralleling transformers, and control of current. rectifier: A component for converting ac to dc by inversion or suppression of alternate half-cycles. self-ventilated machine: A machine that has its ventilating air circulated by means integral with the machine. semiconductor rectifier: A device consisting of a conductor and semiconductor forming a junction. The junction exhibits a difference in resistance to current flow in the two directions through the junction. This results in effective current flow in one direction only. The semiconductor rectifier stack is a single columnar structure of one or more semiconductor rectifier cells. series-wound motor: A dc motor in which the field circuit and armature circuit are connected in series.

Speed is inversely proportional to the square root of load torque. Motor operates at a much higher speed at light load than at full load. shunt-wound motor: A dc motor in which the field circuit is connected either in parallel with the armature circuit or to a separate source of excitation voltage. single-phase circuit: A circuit energized by a single alternating electromotive force.

NOTE—A single-phase circuit is usually supplied through two conductors. The currents in these two conductors, counted outward from the source, differ in phase by 180° or a half-cycle. 23

slip: In an induction machine, the difference between its synchronous speed and its operating speed. It may be expressed in the following ways: 

As a percent of synchronous speed



As a decimal fraction of synchronous speed

23 Notes in text, tables, and figures of a standard are given for information only and do not contain requirements needed to implement this standard.

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

Directly in revolutions per minute

squirrel-cage induction motor: A motor in which the secondary circuit consists of a squirrel-cage winding suitably disposed in slots in the secondary core. squirrel-cage winding: A permanently short-circuited winding, usually uninsulated (primarily used in induction machines), having its conductors uniformly distributed around the periphery of the machine and joined by continuous end rings. stabilized shunt-wound motor: A shunt-wound motor that has a light series winding added to prevent a rise in speed, or to obtain a slight reduction in speed, with increase of load. static converter/inverter: A unit that employs solid state devices such as semiconductor rectifiers or controlled rectifiers (thyristors), gated power transistors, electron tubes, or magnetic amplifiers to change ac power to dc power, dc power to ac power, or fixed-frequency ac power to variable-frequency ac power. switchboard: A metal-enclosed panel or assembly of panels that may contain molded case, insulated case, or power circuit breakers, bolted pressure contact or fusible switches, protective devices, and instruments.

These devices may be mounted on the face or the back of the assembly. Switchboards are generally accessible from the rear as well as from the front; however, they can be front accessible only. synchronous generator: A synchronous ac machine that transforms mechanical power into electric power.

A synchronous machine is one in which the average speed of normal operation is exactly proportional to the frequency of the system to which it is connected. synchronous motor: A polyphase ac motor with separately supplied dc field and an auxiliary (amortisseur) winding for starting purposes. The operating speed is fixed by the frequency (f) of the system and the number of poles (p) of the motor. (Synchronous speed (r/min) = 120f/p). Thus, the speed of the motor can be varied by varying the frequency of the power source. The synchronous motor generally operates at unity power factor and can be used to improve the system power factor. It is generally the motor of choice for ac propulsion systems. tank vessel: A vessel that carries liquid or gaseous cargo in bulk. torque margin: The increase in torque above rated torque to which a motor may be subjected without the motor pulling out of step. This is of particular concern with electric propulsion systems. totally enclosed water/air cooled machine (TEWAC): A totally enclosed machine with integral water-toair heat exchanger and internal fan to provide closed-loop air cooling of the windings. variable speed constant frequency generator (VSCF): An ac generator designed to have a constant frequency output with a variable speed input. This may be accomplished with an induction generator having an ac/ac converter feedback circuit that excites the wound rotor at a frequency to produce a constant frequency output. This may also be accomplished by a synchronous generator whose variable output frequency is fed into a frequency changer that produces a constant output frequency. Basic frequency changers may be of the cycloconverter or dc link type. wound-rotor induction motor: An induction motor in which the secondary circuit consists of polyphase winding or coils whose terminals are either short-circuited or closed through suitable circuits. When provided with collector or slip rings, it is also known as a slip-ring induction motor.

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3.2 Acronyms and abbreviations ABS ABT AFE AHF ASD AVR BOP CEC CENELEC CFR COLREGS CSDU DNV GL dPF EEDI EMC EMI EPS-CONOPS ESWBS FMEA FMECA FOG GDI GL hPF ICD IGBT IMO IPS ITHD IVHD LCI LCL LF LVP MBT MESG MIC MODU MTBF MTBSI MTTR

American Bureau of Shipping automatic bus transfer active front-end active harmonic filter adjustable speed drive automatic voltage regulator blow out preventer Canadian Electrical Code European Committee for Electrotechnical Standardization Code of Federal Regulations International Regulations for Preventing Collisions at Sea column-stabilized drilling unit Det Norske Veritas & Germanischer Lloyd, an international accredited registrar and classification society headquartered near Oslo, Norway. displacement power factor Energy Efficiency Design Index electromagnetic compatibility electromagnetic interference electrical power system concept of operations Expanded Ship Work Breakdown Structure failure mode and effects analysis failure modes, effects, and criticality analysis salt spray apparatus ground detector indicator part of the DNV GL (see above) distortion power factor interface control document insulated gate bipolar transistor International Maritime Organization integrated power system current total harmonic distortion individual voltage harmonic distortion load commutated inverter inductor-capacitor-inductor filer, typically either a 'T' for 'pi' configuration. load factor low voltage protection manual bus transfer maximum experimental safe gap minimum igniting current mobile offshore drilling unit mean time between failures mean time between service interruption mean time to repair

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NRTL PDC PDSS PSID PTI PTO PWM QoS RFI RM&A RMS RTD SCR SEDU SLI SMPS SNVT SOLAS SSL TEAAC TEFC TEWAC THD TPF UCPT UPS VPI VSCF VSD VTHD

Nationally Recognized Testing Laboratory protective device coordination propulsion derived ship service power system interface device power take-in power take-off pulse width modulated quality of service radio frequency interference reliability, maintainability, and availability need definition for acronym resistance temperature detection silicon control rectifier self-elevating drilling unit starting, lighting, and ignition switching mode power supply standard network variable type International Convention for the Safety of Life at Sea solid state lighting totally enclosed air to air cooled totally enclosed fan cooled totally enclosed water/air cooled total harmonic distortion true power factor user-defined configuration property type uninterruptible power supply vacuum-pressure-impregnation variable speed constant frequency variable speed drive voltage total harmonic distortion

4. System engineering 4.1 Introduction Figure 1 shows the design process from concept design to product baseline and the relationship between IEEE Std 45.1-2017 and IEEE Std 45.3. This document (IEEE Std 45.1) provides recommended practices for the Product Design Phase based on the Design Baseline and leading to the establishment of the Product Baseline.

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IEEE 45.3 Concept Design

IEEE 45.3 – Systems Engineering focuses on Concept Design through Baseline Design

Concept Baseline Preliminary Design Preliminary Baseline Baseline Design

Design Baseline IEEE 45.1 – Detailed Design addresses Product Design using the Design Baseline requirements

IEEE 45.1

Product Design Product Baseline

Figure 1 —Design process

4.2 Design baseline A design baseline is an agreement between an owner and a builder that defines the desired product in sufficient detail to allow proceeding with the product design phase.

The electrical power system design baseline should be established at the conclusion of baseline design and maintained using configuration management throughout product design.

The design baseline should consist of the following elements: 

Cover sheet



Drawing index



Drawing tree/document index*



Electrical power system top-level requirements



Systems list



Power system design (single line diagram)



Primary power system parameters



Electrical power system concept of operations (EPS-CONOPS)*



Electrical power system control design



Master equipment list*



Interface control document (ICD)



Computer software



Electric load analysis



Reliability, maintainability, and availability (RM&A) analysis*



Quality of service (QoS) analysis*



Electrical power system corrosion control description*



Failure modes, effects, and criticality analysis (FMECA) 26 Copyright © 2017 IEEE. All rights reserved.

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IEEE Std 45.1-2017 IEEE Recommended Practice for Electrical Installations on Shipboard—Design



Models list*



Simulation results*



Cost considerations



Electrical power system specification



Long-lead electrical procurements



Studies and other reference documents*

 

Testing and acceptance criteria Bibliography

*These items are recommended for more complex vessels such as navel combatants.

4.3 Product design Product design is the final phase in the design process and should build on the design baseline from the baseline design phase. The long-lead items will have been specified and procurements initiated during baseline design. All remaining electrical power system components should be specified, design issue questions should be answered, and no undefined elements should be left in the design. Some additional equipment/material will be procured during this phase to support the construction schedule. The product baseline is the design product from the product design phase.

4.4 Product baseline The product baseline consists of the following components: 24 

Describes the detailed design, including necessary physical (form, fit, and function) characteristics and selected functional characteristics designated for production, acceptance testing, and production test requirements



Identifies the verifications necessary for accepting product deliveries (first article and acceptance instructions)



Identifies and documents the design of any special tooling, software, equipment, and facilities required to manufacture, operate, maintain, calibrate, or inspect items contained in the design



Includes any quality assurance provisions required for first article or acceptance inspection



Includes any unique process specifications required to manufacture, operate, maintain, or calibrate items contained in the design



Identifies any specialized software and documents the operating environment used to author the detailed design



Includes technical data that provides instructions for the installation, operation, maintenance, training, and support of a system or equipment

24

Adapted from IEEE Std 15288.1™.

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5. Power system characteristics 5.1 Electrical power systems architectures 5.1.1 Radial architecture A radial architecture is implemented by interconnecting switchboards with distribution cabling, and then powering loads and load centers/power panels feeding multiple smaller loads via feeder cables from the switchboards. Generators and energy storage typically connect to switchboards. Emergency loads are normally provided power from an emergency switchboard. Mission-critical loads are connected to multiple load centers (typically geographically dispersed) via manual bus transfer (MBT) or automatic bus transfer (ABT) devices. Figure 2 is an example of a radial architecture for a commercial marine vessel, while Figure 3 shows a typical naval vessel.

MAIN SWITCHBOARD

Diesel Generator No. 1

Diesel Generator No. 2

G

G

PORT SHIP SERVICE BUS

SHORE POWER

SHORE POWER AND BUS TIE BUS

BUS TIE

BUS TIE

Diesel Generator No. 3

Diesel Generator No. 4

G

G

STARBOARD SHIP SERVICE BUS

EMERGENCY GENERATOR

TO SHIP SERVICE AND MISSION LOADS/LOAD CENTERS/POWER PANELS (TYPICAL-DISTRIBUTION AS REQUIRED)

G

TO SHIP SERVICE AND MISSION LOADS/LOAD CENTERS/POWER PANELS (TYPICAL-DISTIBUTION AS REQUIRED)

INTERLOCK

EMERGENCY SWITCHBOARD

EMERGENCY BUS

TO EMERGENCY LOADS (TYPICAL-DISTRIBUTION AS REQUIRED)

Figure 2 —Typical commercial marine single-line diagram

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IEEE Std 45.1-2017 IEEE Recommended Practice for Electrical Installations on Shipboard—Design Machinery Room #1

Machinery Room #2 Switchboard (SWBD) Interconnect (Ring Bus)

Machinery Room #3

No. 3 Generator Engine

ABT SWBD

SWBD

SWBD

Vital Loads

SWBD

No. 1 Generator

No. 2 Generator

2

Engine Non-Vital Loads

SWBD

SWBD

SWBD ABT

Vital Loads Switchboard Feeder Cable

SWBD

Non-Vital Loads SWBD SWBD

Figure 3 —Notational radial distribution architecture typically found on a naval warship 5.1.2 Zonal architecture For complex vessels with stringent power system power continuity requirements, a zonal architecture is recommended. This architecture is implemented by dividing the ship into multiple zones, designing a zonal electrical distribution system (ZEDS) for each zone, and integrating the zones with a primary bus/interzonal distribution bus, power generation, and possibly energy storage as shown in Figure 4. Note that power system equipment that is not part of the ZEDS may reside within the boundaries of the zone. Likewise, not all loads (electric propulsion, for example) within the geographic boundaries of the zone are necessarily part of the zone.

Zone #5

Zone #3

Zone #4

Non-Vital Loads

LC

No. 3 Generator Vital Loads

ABT

LC

LC

Non-Vital Loads

Non-Vital Loads

No. 2 Generator

No. 1 Generator

Engine

Engine

Non-Vital Loads Non-Vital Loads Bus Tie

LC

Non-Vital Loads

Vital Loads

SWBD

SWBD

LC

Zone #1

Bus Tie

Bus Tie LC

Non-Vital Loads

Engine

Zone #2

LC

ABT

SWBD

Non-Vital Loads

Non-Vital Loads

LC

LC

Non-Vital Loads

LC

Bus Tie

LC = Load Center SWBD = Switchboard ABT = Automatic Bus Transfer

Figure 4 —Notational zonal electrical power system architecture for a naval warship For a ship, a zone is typically a longitudinal section of the ship with boundaries at water-tight bulkheads.

The number of zones within a ship is a function of the complexity of the ship, its missions, and

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IEEE Std 45.1-2017 IEEE Recommended Practice for Electrical Installations on Shipboard—Design

survivability requirements. A naval warship, for example, would typically have between four and seven zones.

A ZEDS consists of power system elements serving a group of loads and is part of a larger power system.

ZEDS plus the loads it serves comprise a zone. A ZEDS has a limited number of power and control interfaces with the larger encompassing system and has the property that faults within the zone do not propagate outside the zonal boundaries. Furthermore, a design objective of ZEDS and the larger system containing the ZEDS is that loads served by the ZEDS are provided with the type of power, quality of power, and QoS specified by a customer-supplier agreement. Loads served by the ZEDS receive power only via the ZEDS. The power systems elements composing a ZEDS include power conversion equipment, controls, switchgear, cabling, and, optionally, energy storage and generation.

If specified by the customer, a ZEDS isolated from the rest of the power system may be required to operate either for a limited time or on a continuous basis. In either case, the ZEDS will have energy storage and/or generation.

Requirements for a power electronics-based ZEDS are provided by IEEE Std 1826.

5.1.3 Hybrid architectures Special circumstances can result in hybrid power system architectures that do not cleanly fit the definition of either a radial or zonal architecture. If employing a hybrid architecture, analysis is required to verify the system will operate in a satisfactory and stable manner under all operating conditions, achieve QoS and power quality requirements, and meet all other customer requirements.

An example of a hybrid architecture would be power generation and large loads in a ring-bus configuration connected to a ZEDS supplying all other loads.

5.2 Standard systems The following distribution systems are recognized as standard: 

Two-wire with single-phase ac or dc



Three-wire with single-phase ac or dc



Three-phase, three-wire ac



Three-phase, four-wire ac

5.3 Standard voltage The following voltages are recognized as standard, as shown in Table 1.

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Table 1 —Standard voltages Standard Power utilization

Power generation

AC (V)

DC (V)

115, 200, 220, 230, 350, 440, 460, 575, 660, 2300, 3150, 4000, 6300, 10 600, 13 200 120, 208, 230, 240, 380, 450, 480, 600, 690, 2400, 3300, 4160, 6600, 11 000, 13 800

12, 24, 28, 115, 230, 270, 380 See IEEE Std 1709 120, 240 See IEEE Std 1709

Standard voltages and associated power quality are also provided by IEC 60038 (does not provide power quality requirements), IEEE Std 1709, IEEE Std 1826, IEC/ISO/IEEE 80005-1, MIL-STD-1399-300, and MIL-STD-1399-680.

5.4 Standard frequency For ac lighting and power systems, 50 Hz and 60 Hz are standard frequencies. For some military and special service applications, 400 Hz is standard, usually required by ship mission system equipment.

5.5 Selection of voltage and system type In general, voltage selection should take into consideration maximum anticipated load, total power generation capacity, distribution cable weight/volume allocation, available switchgear rated continuous current capability, and any other special considerations unique to the vessel. The following guidelines may be useful in selecting both the system voltage and system type.

For small vessels having minimal power apparatus (up to 15 kW), 120 V, three-phase or single-phase generators may be used, with 115 V, three-phase or single-phase distribution for power and lighting.

Single-phase lighting feeders should be balanced at the switchboard to provide approximately equal load on the three-phase system.

For intermediate-size vessels with power apparatus (up to 100 kW), generators may be 230 V, three-phase or 240 V, three-phase; the power utilization at 220 V or 230 V three-phase, respectively; and lighting distribution at 120 V, three-phase, three-wire or 120/208 V three-phase, four-wire. Power and lighting utilization should be at 115/200 V, three-phase.

For large vessels of a size and type that require a dual voltage system (two systems isolated by transformers operating at different voltages), first consideration should be given to 450 V, 480 V, 600 V, or 690 V generation with power utilization at 440 V, 460 V, 575 V, or 660 V, respectively, and lighting distribution at 120 V or 230 V three-phase, three-wire or 120/208 V, three-phase, four-wire.

For vessels having a very large electrical system requiring higher voltage power generation, consideration should be given to generating ac power at 13 800 V, 11 000 V, 6600 V, 4160 V, 3300 V, or 2400 V with some power utilization at 13 200 V, 10 600 V, 6300 V, 4000 V, 3150 V, or 2300 V, three-phase, respectively, with lower utilization voltages to be derived from transformers. Where dc generation is desired, consideration should be given to employing rated voltages defined in IEEE Std 1709.

For vessels requiring dc power generation, and having little power apparatus, 120 V dc generators are recommended with a 115 V dc lighting and power distribution system. Where an appreciable amount of dc power apparatus is provided, 120/240 V dc, three-wire generators and 230 V dc power distribution system 31 Copyright © 2017 IEEE. All rights reserved.

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IEEE Std 45.1-2017 IEEE Recommended Practice for Electrical Installations on Shipboard—Design

and 115/230 V dc three-conductor lighting feeders may be selected. Branch circuits from lighting panelboards should be 115 V dc two-wire.

Ships with loads requiring 28, 270, or 380 V dc are recommended to provide these loads with power from point-of-use power conversion.

User equipment shall be designed to operate normally when supplied power with a nominal voltage between the nominal power utilization and nominal generation voltages. The difference between the nominal generation voltage and the power utilization voltage accounts for voltage drop due to cables and other distribution system equipment.

5.6 AC power system characteristics Ac power distribution systems should maintain the system characteristics described in MIL-STD-1399-300, MIL-STD-1399-680, or Table 2 under all operating conditions. Power-consuming equipment should operate satisfactorily under the conditions described in MIL-STD-1399-300, MIL-STD-1399-680, or Table 2, and it should be designed to withstand the power interruption, transient, electromagnetic interference (EMI), radio frequency interference (RFI), and insulation resistance test conditions inherent in the system. Power-consuming equipment requiring a nonstandard voltage or frequency for successful operation should have integral power conversion capability. Power-consuming equipment should not have inherent characteristics that degrade power quality.

Table 2 —Alternating current (ac) power characteristics Characteristics

Limits

Frequency a) Nominal frequency b) Frequency tolerances c) Frequency modulation d) Frequency transient: 1) Tolerances 2) Recovery time e) The worst-case frequency excursion from nominal frequency resulting from item b), item c), and item d) 1) combined, except under emergency conditions.

Voltage User voltage tolerance: 1) Average of the three line-to-line voltages 2) Any one line-to-line voltage, including item a) 1) and line voltage unbalances item b) b) Line voltage unbalance c) Voltage modulation d) Voltage transient: 1) Voltage transient tolerances 2) Voltage transient recovery time e) Voltage spike (peak value includes fundamental)

50/60 Hz ± 3% 0.5% 4% 2s 5.5%

a)

f)

± 5% ± 7% 3% 5% ± 16% 2s ± 2500 V (380−600 V) system 1000 V (120−240 V) system

The maximum departure voltage resulting from item a) 1) and item d) combined, except under transient or emergency conditions

± 6%

g) The worst-case voltage excursion from nominal user

± 20%

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IEEE Std 45.1-2017 IEEE Recommended Practice for Electrical Installations on Shipboard—Design

Characteristics

Limits

voltage resulting from item a) 1), item a) 2), and item d) 1) combined, except under emergency conditions Emergency conditions a) b) c) d)

Frequency excursion Duration of frequency excursion Voltage excursion Duration of voltage excursion: 1) Lower limit (– 100%) 2) Upper limit (+ 35%)

– 100% to + 12% Up to 2 min – 100% to + 35% Up to 2 min 2 min

Definitions: a) Frequency 1) Nominal frequency: The designated frequency (fnominal) in Hz. 2) Frequency tolerance: The maximum permitted departure from nominal frequency during normal operation, excluding transient and cyclic frequency variations. It includes variations caused by load changes, environment (temperature, humidity, vibration, inclination), switchboard meter error, and drift. Tolerances are expressed in percentage of nominal frequency.

3) Frequency modulation: The permitted periodic variation in frequency during normal operation that might be caused by regularly and randomly repeated loading. For purposes of definition, the periodicity of frequency modulation should be considered as not exceeding 10 s.  f max − f min  = Frequency Modulation (%)   × 100  2 × f nominal 

4) Frequency transient tolerance: A sudden change in frequency that goes outside the frequency tolerance limits, returns to, and remains inside these limits within a specified recovery time after initiation of the disturbance. Frequency transient tolerance is in addition to frequency tolerance limits.

5) Frequency transient recovery time: The time period from the start of the disturbance until the frequency recovers and remains within frequency tolerance limits. b) Voltage 1) User voltage tolerance: The maximum permitted departure from nominal user voltage during normal operation, excluding transient and cyclic voltage variations. It includes variations such as those caused by load changes, environment (temperature, humidity, vibration, inclination), switchboard meter error, and drift.

2) Line voltage unbalance tolerance (three-phase system): The difference between the highest and lowest line-to-line voltages.  E max − Emin  Line Voltage Unbalance Tolerance = (%)   × 100  Enominal 

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Characteristics

Limits

3) Voltage modulation (amplitude): The periodic voltage variation (peak to valley) or the user voltage that might be caused by regularly or randomly repeated pulsed loading. The periodicity or voltage modulation is considered to be longer than 1 Hz and less than 10 s.

Voltages used in the following equation shall be all-peak or all-rms:  E max − Emin  = Voltage Modulation (%)   × 100  2 × Enominal 

4) Voltage transient i) Voltage transient tolerance: A sudden change (excluding spikes) in voltage that goes outside the user voltage tolerance limits and returns to and remains within these limits within a specified recovery time longer than 1 ms after the initiation of the disturbance.

The voltage transient tolerance is in addition to the user voltage tolerance limits. ii) Voltage transient recovery time: The time elapsed from initiation of the disturbance until the voltage recovers and remains within the user voltage tolerance limits.

5) Voltage spike: A voltage change of very short duration (less than 1 ms). c) Waveform 1) Total harmonic distortion (THD) (of a sine wave): The ratio in percentage of the rms value of the residue (after elimination of the fundamental) to the rms value of the fundamental.

2) Single harmonic (of a sine wave): The ratio in percentage of the rms value of that harmonic to the rms value of the fundamental.

3) Deviation factor (of a sine wave): The ratio of the maximum difference between corresponding ordinates of the wave and of the equivalent sine wave to the maximum ordinate of the equivalent sine wave when the waves are superimposed in such a way that they make the maximum difference as small as possible.   Maximum Deviation = Deviation Factor (%)   × 100  Maximum ordinate of the equivalent sine wave 

d) Emergency conditions 1) A situation or occurrence of a serious nature that may result in electrical power system interruptions or deviations, such as the occurrence of ship service generator failure and the emergency generator coming online. aFor ships with electric propulsion or other adjustable speed drive (ASD) loads, higher voltage distortion can be accepted on a dedicated power bus if the equipment connected to the dedicated power bus is designed and tested for the actual conditions.

5.7 DC power systems characteristics For vessels utilizing a dc power distribution system or subsystem, Table 3 provides recommended requirements.

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Table 3 —DC power systems recommended power quality requirements DC voltage level

Recommended power quality requirements

28 V or 270 V 380 V ≥ 1000 V

MIL-STD-704F ETSI EN 300 132-3-1 IEEE Std 1709

5.8 Key electrical power system design inputs 5.8.1 Electric load analysis The electric load analysis developed in previous design phases documents the basis for estimating the operating load for different ship operating conditions. The electric load analysis is updated as part of product design (See 4.3). The electric load analysis is used to size major electrical equipment and is updated during this phase to provide confidence that the equipment will meet the demand load. It is also used to ensure extra capacity is provided at ship delivery as required by the customer. See 22.2 for additional information.

5.8.2 Ship consumer equipment locations The locations of electric power consumer loads have a direct bearing on configuration of the electrical distribution system. This information is needed to determine locations, quantities, and sizes of load centers, power panels, transformers, etc. that will be required to efficiently supply power to the loads. In early design phases, compartment names on the ship general arrangements are used to estimate equipment locations. As the ship design progresses, specific locations of consumer loads will be defined and adjustments to the electrical distribution system will need to be made.

5.9 Quality of service (QoS) 25 5.9.1 Introduction QoS is a metric of how reliably the power system provides power to the loads. It is calculated as a mean time between service interruptions (MTBSI). QoS is a reliability metric; as such the calculation of QoS metrics does not take into account survivability events such as collisions, fires, or flooding. QoS does take into account equipment failures and normal system operation transients.

Equipment designers or manufacturers should provide QoS information to the electric system designer.

Loads should be categorized into four QoS categories: uninterruptible, short-term interrupt, long-term interrupt, and exempt.

5.9.2 Service interruption A service interruption is any interruption in service or power quality degradation outside of acceptable parameters for a period of time that results in the load’s parent system not being capable of meeting its requirements. The duration of service interruption is measured relative to two system dependent times: t1 25 Quality of Service (QoS) is a concept developed by the U.S. Navy to drive electrical power system reliability into the system design.

The concept is recommended for other vessels where power system reliability is a key requirement.

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and t2. Different electrical power system-load interfaces may have different values for t1 and t2 based on the choice of power system components.

System times are system dependent quantities that can have a major impact on cost and should, therefore, be selected very carefully and include mission functionality.

5.9.3 Reconfiguration time (t1) Reconfiguration time (t1) is defined as the maximum time to reconfigure the distribution system without bringing on additional generation capacity.

The t1 is defined by the time delays in the system protection coordination and system reconfiguration. For systems with traditional switchgear, historic values of 0.5 s, 1 s, 2 s, and 3 s should be used. For designs with fast power electronics, t1 of 0.0001 s, 0.001 s, 0.01 s, 0.05 s, 0.1 s, and 0.2 s should be used.

Reconfiguration time should be specified and included as part of the EPS-CONOPS. 5.9.4 Generator start time (t2) Generator start time (t2) is defined as the maximum time to bring the slowest power generation module online. The t2 is typically on the order of 1 to 5 min for naval vessels. Commercial vessels must bring the generator module online within 30 s or seek regulatory relief.

5.9.5 Mean time between service interruptions Different operating conditions of the ship may have different requirements for the MTBSI. These different operating conditions are generally defined and the MTBSI calculated over an operating cycle or, alternately, a design reference mission. Associated with each operating condition is a machinery concept of operation that details the expected policies for redundancy, rolling reserve, etc. needed to achieve the customer specified MTBSI. MTBSI should be specified and included as part of the EPS-CONOPS. 5.9.6 QoS categories 5.9.6.1 Uninterruptible load Loads that cannot tolerate service interruptions greater than time t1 are categorized as uninterruptible loads.

The power system should be designed to provide each uninterruptible load the minimum achievable service interruption (or lower than the longest duration that a load can tolerate an interruption) with a reliability in excess of the specified MTBSI. 5.9.6.2 Short-term interrupt load Loads that can tolerate service interruptions of duration t1 and cannot tolerate service interruptions of duration t2 are categorized as short-term interrupt loads, which are common on complex vessels such as naval combatants.

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The power system should be designed to limit service interruptions to short-term interrupt loads to less than t1 in duration. Service interruptions greater than t1 in duration for a given load should not occur on average more frequently than the specified MTBSI. 5.9.6.3 Long-term interrupt loads Loads that can tolerate service interruptions of duration t2 are categorized as long-term interrupt, which are common on complex vessels such as naval combatants.

With the exception of exempt loads, the power system should be designed to limit service interruptions to long-term interrupt loads to less than t2 in duration. Service interruptions greater than t2 in duration to long-term interrupt loads (except exempt loads) should not occur on average more frequently than the specified MTBSI. 5.9.6.4 Exempt loads Exempt loads are a special case of long-term interrupt loads that do not require restoration within t2, which are common on complex vessels such as naval combatants.

For integrated power system (IPS) configurations where propulsion and ship service power are provided by the same set of power generation modules and prime movers, sufficient redundancy in generation is not provided to enable the ship to achieve its maximum speed with any one generator out of service. Propulsion power for IPS ships may thus be split into three categories: short-term interrupt load, long-term interrupt load, and exempt load. The installed generation capacity of the ship must be capable of supporting all categories of load for all loads for every operating condition with all generators online, and must support all loads except the exempt load with one generator out of service. Unless otherwise specified by the customer, that portion of propulsion load needed to exceed the minimum mission speed is exempt load.

The concept of the exempt load is only used in sizing the installed generation capacity of the ship. In operation of the power system, exempt load is treated as long-term interrupt load.

5.10 Electrical power system concept of operation (EPS-CONOPS) An EPS-CONOPS should either be updated from previous stages of design or prepared to document the expected manner of operation during different operational cases. IEEE Std 45.3 provides details for the content of an EPS-CONOPS. The EPS-CONOPS includes scenarios that all ships encounter as well as scenarios unique to the particular vessel’s marine sector. Common scenarios include in port, normal transit, anchored, recovery from casualty. Sector-unique scenarios include container off load and on load, underway lightering of petroleum, combat, and humanitarian relief.

The EPS-CONOPS articulates power system attributes that should be optimized for each of the expected scenarios. Typical attributes include QoS, energy efficiency, safety, emissions, and safety of life at sea to meet the ship’s mission and business needs. It should also include margin policy and provisions for future changes, and should foster a design that meets or exceeds the requirements and expectations for the vessel.

The EPS-CONOPS address the human systems interface; an important aspect is the interaction between humans and the electric power system equipment.

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IEEE Std 45.1-2017 IEEE Recommended Practice for Electrical Installations on Shipboard—Design

5.11 Marine environmental conditions 5.11.1 Normal environmental conditions Systems and equipment should be suitable for continuous operation under the following shipboard conditions: 

Exposure to moisture-laden and salt-laden atmosphere, weather, sun, high wind velocities, and ice.



Equipment and systems shall be designed for temperature extremes and conditions expected.

Typically, the following conditions can be used: ambient temperature values of 40 °C in accommodation areas and similar spaces; 45 °C in main and auxiliary machinery spaces; 50 °C for rotating machinery and propulsion equipment in main and auxiliary machinery spaces containing significant heat sources such as prime movers and boilers; and 65 °C in the uptakes of machinery spaces containing prime movers and boilers; all at relative humidity values up to 95%. The design value for seawater cooling temperature should be 32 °C.



Roll and pitch of a vessel underway, as shown in Table 4.

Table 4 —Roll and pitch requirements

Ship service equipment Emergency equipment a Switchgear

Static (°)

Roll

Pitch

Dynamic (°)

Static (°)

Dynamic (°)

15

22.5

5

22.5

22.5

10

10

45

45

45

45

7.5

In vessels designed for carriage of liquefied gases and of chemicals, the emergency power installation is to remain operable with the vessel flooded to its permissible athwartship inclination up to a maximum of 30°. a



Vibration of a vessel underway: Electrical equipment should be constructed to withstand at least the following:  Vibration frequency range of 5 Hz to 50 Hz with a velocity amplitude of 20 mm/s  Peak accelerations due to ship motion in a seaway of ± 5.9 m/s2 for ships exceeding 90 m in length, and ± 9.8 m/s2 for smaller ships, with a duration of 5 s to 10 s

5.11.2 Abnormal environmental conditions Special conditions for a specific ship design or operating arrangement may require special consideration – typical for complex ships such as naval combatants. Examples of such conditions include, but are not necessarily limited to the following: 

Exposure to damaging fumes or vapors, excessive or abrasive dust, steam, salt-spray, ice, sunlight, physical damage, and so on



Exposure to high levels of shock and vibration



Exposure to high or low temperatures



Operation in flammable atmospheres



Exposure to unusual loading or unloading conditions affecting list and trim



Unusual operating cycles, frequency of operation, poor power quality, special insulation requirements, stringent or difficult maintenance requirements, and so on

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6. Electrical power system elements 6.1 Introduction An electrical power system, in general, can be decomposed into up to six different types of elements based on functionality: power generation, power distribution, power conversion, energy storage, electrical power system supervisory control, and loads. These elements are described in this clause. The equipment implementing each element may include power electronics to convert and condition the electrical power.

Guidance for the design and application of power electronics in electrical power systems on ships is provided in IEEE Std 1662.

6.2 Power generation Power generation consists of equipment that converts an energy source (such as fuel) into electrical power for use by loads via one or more power distribution systems. Power generation equipment exchanges control and information signals with the electrical power system supervisory control and may interface with other distributed systems such as a seawater system, steam generation system, fuel service system, intakes, and exhaust.

Power generation equipment using rotating electrical generator sets generally includes a steam turbine, gas turbine, or a diesel engine prime mover; a generator; possibly power electronics; auxiliary support submodules; and module controls. Other possible power generation technologies include rotating generators directly connected to the propulsion train, direct conversion (e.g., solar cells, fuel cells), and wind-driven turbines.

Power generation equipment should regulate its output voltage and frequency (for ac systems).

Additionally, if multiple generator sets are intended to operate in parallel, provisions should be made for the stable sharing or apportioning of real power and reactive power (for ac systems). For ac systems, real power sharing is generally implemented through frequency droop or other signals between paralleled units’ speed governors. For ac systems, reactive power sharing is generally implemented through voltage droop or other signals between paralleled units’ voltage regulators. For dc systems, real power sharing is generally implemented through voltage droop or other signals between paralleled units’ voltage regulators. If power generation equipment and/or the output of power conversion equipment of different types or ratings is intended to operate in parallel, the dynamic performance of the power system should be verified for stable operation and adherence to transient power quality requirements.

The design of the fault current capability of power generation equipment should be coordinated with the fault protection equipment in the distribution system. The differing fault current characteristics of rotating machines and power electronics should be considered when designing the protection system.

See Clause 8 for additional requirements for power generation.

6.3 Power distribution 6.3.1 General Power distribution systems transfer electrical power between other power system elements. They also provide fault current protection as well as implement different power system architectures. Power distribution systems typically consist of cables, switchgear, load centers, power panels, load monitoring 39 Copyright © 2017 IEEE. All rights reserved.

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equipment, and fault protection equipment. Power distribution equipment communicates with the electrical power system supervisory control and may communicate with other distributed systems. Power distribution may include power electronics and distribution transformers to directly provide the type and quality of power required by specific loads or a small grouping of loads.

A power system may have one or several power distribution systems, each with its own bus of potentially different voltage and power type. A bus of one type should be galvanically isolated from buses of all other types. Historically, mechanical drive ships have had one power distribution system that distributed 450 V to 480 V, three-phase, 50 Hz to 60 Hz power. More recently, large ships and those with electric propulsion have employed a medium voltage ac power distribution system interconnected via transformers with a low voltage (450 V to 480 V) ac power distribution system. A ship may have a single medium voltage power distribution system that feeds multiple electrical zones via power conversion equipment (e.g., transformers, solid-state power converters). Under such conditions, each electrical zone will have its own zonal power distribution system.

Switchgear consists of the equipment, such as electrical disconnect switches, fuses, and circuit breakers, used to control power to, protect, and isolate electrical equipment. Recommendations for ac switchgear are provided by IEEE Std 45.7. Recommendations for cable systems are provided in IEEE Std 45.8.

Requirements for connecting to shore utility power are provided by IEC/ISO/IEEE 80005-1.

See Clause 9 for additional requirements for power distribution.

6.3.2 Primary bus A primary bus is a term reserved for a medium voltage ac or dc bus and applies only to vessels with a medium voltage bus. A primary bus may be implemented as multiple buses for redundancy, criticality, or safety. A primary bus usually is only directly connected to a few large loads; the majority of the loads are powered from other buses that connect to the primary bus via power conversion equipment (e.g., transformers, solid-state power converters).

In selecting the voltage for the primary bus, consideration should be given to using the standard voltages in IEC/ISO/IEEE 80005-1 to simplify connections to shore utility power while in port.

6.3.3 Distribution bus A distribution bus provides power to loads throughout a ship or a zone. Multiple distribution buses may be utilized as necessary for the vessel design. Distribution buses typically support voltages between 400 V and 1000 V. 6.3.4 Secondary low voltage bus A secondary low voltage bus provides low voltage directly to equipment, appliances, or appliance outlets.

6.3.5 Special bus A special bus provides power for unique purposes such as medical use, control system power, special control, or propulsion.

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6.4 Power conversion Power conversion equipment converts electrical power from the type and quality required by one power distribution system to the type and quality required by another power distribution system. Power conversion equipment technologies include power electronics, transformers, and rotating motor-generator sets. Note that power electronics and transformers are not unique to power conversion equipment and may be part of other power system elements. Power conversion equipment exchanges control and information signals with the electrical power system supervisory control. Power conversion equipment may interface with other distributed systems such as a cooling water system and ventilation systems.

The simultaneous paralleling of the primaries and the secondaries of two or more transformers is not recommended unless provisions are provided to limit circulating currents. These circulating currents must be included in load flow analyses and in calculating the required current ratings of switchgear and cables.

See Clause 10 for additional requirements for power conversion.

6.5 Energy storage An energy storage element stores electrical energy received from a distribution system that later may be used to provide power back to the distribution system or to a dedicated load. Energy storage is typically employed to achieve QoS requirements but may also fulfill power quality and other system requirements, including high energy loads with unique power profiles. An energy storage element should protect the distribution system to which it connects from faults internal to the energy storage element. Additional requirements for energy storage are provided by IEEE Std 1826 and Clause 11.

6.6 Electrical power system supervisory control 6.6.1 General An electrical power system supervisory control monitors, controls, reconfigures, protects, and coordinates the operation of an integrated electrical power system. The supervisory control may be centralized or distributed. Recommendations for the overall machinery control system, including the electrical power system supervisory control, are provided in IEEE Std 45.2 and Clause 12.

Typical electrical power system supervisory control functions could include the following processes as appropriate for the vessel type:  Remote monitoring and control of electrical power system equipment  Resource planning and system configuration to support the EPS-CONOPS  Mission priority load shedding  Coordination of fault detection, fault isolation, and reconfiguration  Optimization of QoS and QoS load shedding  Interfacing with the overall machinery control system  Perfomance analysis, parameter trending, and logging

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IEEE Std 45.1-2017 IEEE Recommended Practice for Electrical Installations on Shipboard—Design

Additionally, the electrical power system supervisory control design should facilitate the following processes:  Maintenance support (such as special modes, electrical isolation, and tag-outs)  Training The electrical power system supervisory control software may reside in hardware contained in other power system elements or may reside in an external distributed computer system. The software should interact with the human operators through a human-computer interface. Incorporating this human-computer interface as part of a ship wide monitoring and control system is recommended.

6.6.2 Power system interface device (PSID) A PSID is equipment that communicates control and monitoring signals with the integrated electrical power system supervisory controller to monitor and control individual loads, in accordance with the EPS-CONOPS. A PSID may also provide custom power to a specific load. PSIDs may be part of the power system or may be part of an external system. A PSID should be used for equipment that requires a connection to the machinery control system but does not have the inherent ability to make such a connection.

6.7 Loads 6.7.1 General Loads may simultaneously be part of multiple systems and may therefore communicate with multiple supervisory controllers for different systems. For example, cargo cooling systems may communicate with the chill-water system, electrical power system, etc. For the electrical power system, loads are categorized by their ability to directly communicate with the power system control.

Additional requirements for loads are provided in Clause 13 through Clause 20.

6.7.2 Uncontrolled load Uncontrolled loads interface only to the power system for electrical power and do not communicate directly with the power system control. An uncontrolled load may communicate indirectly with the power system control via a PSID. Unless a simple load can be commanded to shut down via a PSID, an uncontrolled load is typically shed by switching off the power feed to the load without prior notification.

6.7.3 Controlled load Controlled loads interface to the power system control through a control interface. Controlled loads may have the capability to have their operational state changed by the power system control. For example, the power system control may command a controlled load to reduce load or switch off instead of simply switching off the power. Controlled loads may also communicate with other system supervisory controllers.

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IEEE Std 45.1-2017 IEEE Recommended Practice for Electrical Installations on Shipboard—Design

6.7.4 Large loads Any single load that may require more than 20% of the online power generation capacity supplying that load in any operating condition is considered a large load. A propulsion motor and associated drive is a good example of a large load. For power systems incorporating large loads, the dynamic performance of the power system should be verified for stable operation and adherence to transient power quality requirements.

7. Power system design 7.1 Power generation and energy storage capacities 7.1.1 General requirements For any ship operating condition, 95% of the total power generation capacity of all online generator sets and energy storage minus 95% of the rating of the largest online generator set must be greater than the sum of the online uninterruptible and short-term interruptible loads. For zonal architectures, if the power from energy storage or a generator set can serve only in-zone loads, then any energy storage or generator set power capacity in excess of the sum of that zone’s uninterruptible and short-term interruptible load should not be counted in the total power generation capacity. The 95% factor is an allowance for variation in load due to equipment cycling on and off.

7.1.2 Nonintegrated ship service power and propulsion power systems In designs where the majority of the ship’s propulsion power is not provided via the electrical power system, the loss of use of the generating unit with the highest power rating for any reason (e.g., failure, maintenance) shall not impact the ability of the electrical power generation plant to supply maximum endof-service-life ship service electric load for any ship operating condition with the remaining generators at 95% rated power. 26 7.1.3 Integrated power systems (IPSs) IPSs are systems where the majority of propulsion power and ship service power are supplied from a common electrical power generating plant. The power generating plant shall be designed to provide the maximum margined electric load with service life allowance (including design propulsion load) for any ship operating condition at the design rating of the generating plant. The loss of use of the generating unit with the highest power rating for any reason (e.g., failure, maintenance) shall not impact the ability of the electrical power generation plant to provide the maximum of the margined electric load with service life allowance (including design propulsion load) less exempt load for any ship operating condition. Unless otherwise specified, propulsion load above the minimum of that required to achieve one half of the design speed or 7 knots (whichever is less) is exempt load. When paralleled, each generator shall maintain paralleled loading within ±5% of its rated portion of the operating load. The generator sets shall be designed for a 110% continuous overload rating.

Additionally, at least one of the two following criteria shall be met:

26

This requirement is often called the “N-1” rule.

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IEEE Std 45.1-2017 IEEE Recommended Practice for Electrical Installations on Shipboard—Design



The IPS control system shall prevent overloading of the generators. When sufficient power is being provided to the propulsion motor(s), the IPS control system shall have the ability to prevent overloading of the generators by managing the power provided to the propulsion motor(s).



The power generating plant shall be designed to provide the maximum margined electric load with service life allowance (including design propulsion load) at 95% of the design rating of the generating plant.

7.1.4 Special cases A power take-in (PTI) (also known as a hybrid electric drive) incorporates an electric auxiliary propulsion motor and augments a mechanical drive system. If a hybrid electric drive is installed essentially for fuel economy and is not required to achieve the ship’s design maximum speed, the customer should specify whether the hybrid electric drive load is considered for establishing generator or energy storage module power capacity.

A power take-off (PTO) (also known as propulsion derived ship service (PDSS)) consists of an electrical generator connected to the drive shaft of a mechanical drive system. (It may also include power electronics to convert the power produced by the generator to the frequency and voltage of the power distribution system.) If a PDSS PTO is installed, its capacity may be included in the total generating capacity of the ship if the electrical power generation capacity is independent of the propulsion power at all times.

A bidirectional hybrid electric drive system performs both functions (PTO and PTI) with a single set of equipment. The electric machine mechanically attached to the propulsion system acts as either a motor or a generator depending on operating mode. A power converter acts as either a motor drive or inverter synthesizing distribution bus voltage and frequency depending on the operating mode. In this arrangement, the power capacity and power draw should be included in the electric load analysis as appropriate for the operational conditions. The EPS-CONOPS should detail the intended operating mode for each operating condition.

Some ships with large maneuvering thrusters may have operational conditions where the propulsion loads are mostly electric and a significant fraction of the electric load. For these operational conditions, the criteria of 7.1.3 apply.

7.2 Power conversion and transformer ratings Power conversion equipment and transformers should have a power rating sufficient to satisfy the worstcase anticipated load including margin and service life allowance. If the power conversion equipment is modular and extra capacity can be easily added at a later date, then the power conversion equipment and associated cabling should be designed to incorporate sufficient capacity to satisfy the worst-case anticipated load including margin and service life allowance, but need provide only sufficient modules at delivery to satisfy the worst-case anticipated load without service life allowance.

Single-phase transformers are normally rated in kilovolt-amperes (megavolt-amperes) by multiplying the open-circuit voltage of the secondary by the full-load current, even though these two conditions do not happen at the same time. Hence, the actual amount of kilovolt-amperes delivered by the transformer has to take into account the regulation of the transformer. Similarly, three-phase transformers are normally rated in kilovolt-amperes (megavolt-amperes) by multiplying the open-circuit line-to-line voltage by the full-load current and the square root of 3.

The calculation of the worst-case anticipated load should account for the impact of cycling loads.

Additionally, the ability of the power conversion and transformers to provide in-rush current to load equipment and to provide adequate, but not too much, fault current to enable proper coordination of circuit breakers must be evaluated.

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IEEE Std 45.1-2017 IEEE Recommended Practice for Electrical Installations on Shipboard—Design

7.3 Emergency power 7.3.1 General Emergency power is required by regulatory authorities and classification societies depending on vessel type, tonnage, and voyage. The recommendations in this document are general. For specific requirements, consult the appropriate regulatory authorities and classification societies.

Every vessel should be provided with a self-contained emergency source of electric power, generally a diesel-engine generator, gas turbine-driven generator, or storage batteries (for integrated power systems see 15.5.1). These emergency sources of power and an emergency switchboard should be located in a space separate and remote from the main switchboard, that is above the uppermost continuous deck, aft of the collision bulkhead, outside the main machinery compartment, and readily accessible from the open deck.

The emergency switchboard should be in the same compartment as the emergency generator set and in a compartment adjacent to the storage battery room.

When a compartment containing the emergency source of electric power, or vital components thereof, adjoins a space containing either the ship’s service generators or machinery necessary for the operation of the ship’s service generators, all common bulkheads and decks should be protected by structural fire boundaries (insulation). This protection should prevent an excessive temperature rise in the space containing the emergency source of electric power, or vital components thereof, for a period of at least 1 h in the event of fire in the adjoining space.

If equipment requires an emergency power supply with characteristics other than those directly available from the emergency sources, the motor-generators, converters, rectifiers, or other apparatus supplying this equipment should automatically start and assume the load upon establishment of emergency supply.

Indication should be provided in the machinery space, preferably at the principal propulsion control station, to indicate when the emergency generator is operating and when the emergency storage battery is being discharged.

7.3.2 Emergency generators Emergency generator(s) should be sized to supply 100% of connected loads that are essential for safety in an emergency condition. Where redundant equipment is installed so that not all loads operate simultaneously, these redundant loads need not be considered in the calculation.

The prime movers of generators should be provided with all accessories necessary for operation and protection of the prime mover, including a self-contained cooling system that ensures continuous operation in an ambient temperature of 50 °C, or as required by local or regional codes and regulations.

Any liquid fuels used should have a flash point of 43 °C minimum.

Emergency generators should be capable of carrying a full rated load within 45 s after loss of the normal power source with the intake air, room ambient temperature, and starting equipment at a minimum temperature specified for the application.

Except for a thermostatically controlled, electric water-jacket heater connected to the emergency bus, emergency generator prime movers should not require a starting aid to meet this requirement.

Prime movers of emergency generator sets should start by hydraulic, compressed air, or electrical means.

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IEEE Std 45.1-2017 IEEE Recommended Practice for Electrical Installations on Shipboard—Design

Hydraulic starting systems should be automatically maintained within the predetermined pressure limits and be electrically energized from the emergency bus. Provision for manual recharge should be provided.

The starting air receiver for compressed air starting systems should be supplied from one of the following sources of air: 

The main or auxiliary compressed air receivers with a check valve in the emergency generator room to prevent backflow of compressed air to the ship service system; there should be a handcranked, diesel-powered air compressor for recharging the air receiver.



An electrically driven air compressor that is automatically operated and is powered from the emergency power source. If this compressor supplies other auxiliaries, there should be a check valve at the inlet of the starting air receiver to prevent backflow of compressed air to the other auxiliaries, and there should be a hand-cranked, diesel-powered air compressor for recharging the air receiver.

When an emergency generator is operated in emergency mode, the system performance should be such that the steady state voltage for any increasing or decreasing load between zero and full load at rated power factor should not vary at any point more than ±3.5% of rated generator voltage between reactive load change from 0% to 60% of the continuous kVA rating. For emergency sets under transient conditions, the values may be increased to ±4% in not more than 5 s.

Emergency generators should maintain proper lubrication and not spill oil when subjected to the marine environmental conditions of 5.11.

Emergency generator sets should shut down automatically upon loss of lubricating oil pressure, overspeed, or operation of a fixed fire extinguishing system in the emergency generator room.

Diesel engine prime movers should be provided with an audible alarm that sounds on low oil pressure and high cooling water temperature.

An independent fuel supply should be provided for prime movers. A fuel tank should be sized for the number of hours of full load operation as determined for the specific application.

Each emergency generator should be equipped with starting devices with an energy storage capability of at least six consecutive starts. A single source of stored energy, with the capacity for six starts, should be protected to preclude depletion by the automatic starting system, or a second source of energy should be provided for an additional three starts within 30 min. If, after three attempts, the generator set has failed to start, an audible and visual start failure alarm should be activated in the main machinery space control station and on the navigation bridge. The starting sequence should be automatically locked-out until an operator can initiate the final three starting attempts from the emergency generator space.

7.3.3 Emergency energy storage Where the emergency source of power is energy storage (such as a storage battery), it should be capable of carrying the emergency load without recharging while maintaining the voltage of the energy storage throughout the discharge period within +5% and −12% of its nominal voltage. If the energy storage is not normally connected to the emergency switchboard, it should be automatically connected in the event of failure of the main power supply.

When energy storage is supplied, appropriate means should be furnished for providing power from the batteries to ac loads.

When energy storage is used as the source of emergency lighting and power, transfer to the energy storage should be automatic upon failure of the ship service source. Upon restoration of ship service power and an 46 Copyright © 2017 IEEE. All rights reserved.

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IEEE Std 45.1-2017 IEEE Recommended Practice for Electrical Installations on Shipboard—Design

appropriate time delay, the emergency system should be automatically reconnected to the ship service source.

See Clause 11 for general requirements applicable to energy storage installation.

7.3.4 Emergency power distribution system The emergency, interior communication and electronics switchboards must meet all requirements as detailed in IEEE Std 45.7.

The emergency switchboard should be supplied during normal operation from the main switchboard by an interconnecting feeder. This interconnecting feeder should be protected against short-circuit and overload at the main switchboard and, where arranged for feedback, protected for short-circuit at the emergency switchboard. The interconnecting feeder should be disconnected automatically at the emergency switchboard upon failure of the main source of electrical power. Means shall be provided to prevent auto closing of the emergency generator circuit breaker should a fault occur on the emergency switchboard.

Normal power from the ship’s generating plant for the emergency loads should be supplied to the emergency loads by an automatic transfer device (i.e., circuit breaker, contactor, automatic transfer switch, and so on) and located remotely from the main switchboard. When installed in switchboards, the automatic transfer device should use electrically operated circuit breakers when installed in switchboards. When independently enclosed, the automatic transfer device should be of the equipment type with coils energized only during the transfer operation. Automatic transfer switches should conform to the requirements of UL 1008 or IEC 60947-6-1.

Upon interruption of normal power, the prime mover driving the emergency power source should start automatically. When the voltage of the emergency source reaches 85% to 95% of nominal value, the emergency loads should transfer automatically to the emergency power source. The transfer to emergency power should be accomplished within 45 s after failure of the normal power source. If the system is arranged for automatic retransfer, the return to normal supply should be accomplished when the available voltage is 85% to 95% of the nominal value and the expiration of an appropriate time delay. The emergency generator should continue to run without load until shut down either manually or automatically by use of a timing device.

If fast transfer schemes (less than 15 cycles) are used, the ABT devices feeding motor loads should be equipped with an adjustable time delay to permit low voltage protection (LVP) motor controllers to open.

Regulatory requirements typically do not allow non-emergency loads to be connected to an emergency switchboard. However, for some complex designs such as naval combatants where an “emergency” generator provides back-up power for a limited amount of ship’s loads, then: 

For ready availability of the emergency source of electrical power to emergency loads, arrangements should be made, where necessary, to automatically disconnect non-emergency loads from the emergency power source upon loss of ship’s normal power.



If any non-emergency loads are connected to the emergency switchboard and if the system is arranged for feedback operation (through the interconnection feeder), they should automatically be disconnected at the emergency power source upon detection of 95% of full load current of the emergency generator to prevent an overload condition.



Protective devices and circuitry shall be provided to automatically disconnect the interconnection feeder and any non-emergency loads should a main power failure occur while the emergency generator is running (i.e., exercising or testing).

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IEEE Std 45.1-2017 IEEE Recommended Practice for Electrical Installations on Shipboard—Design

The emergency switchboard should be arranged to prevent parallel operation of an emergency power source with any other source of electrical power (i.e., main power), except where suitable means are taken for safeguarding independent emergency operation under all circumstances. This will allow for the emergency generator to be used to supply non-emergency loads. This is useful when exercising and testing the emergency generator(s).

Where parallel operation is possible and allowable by regulatory rules, the emergency generator shall be equipped with the appropriate synchronizing controls in accordance with IEEE Std 45.7.

7.3.5 Emergency switchboard configuration If two (or more) ship service generating plants are provided, with paralleled or automatic feed to a distribution switchboard, normal supply to the emergency switchboard should be from the distribution switchboard.

If a common distribution switchboard is not provided, there should be an emergency bus feeder from each service switchboard connected to an ABT device on the emergency switchboard.

Upon failure of ship service supply, the temporary bus should automatically be transferred to battery supply and should return to the normal supply when the final bus is energized by the emergency generator or by restoration of ship service power.

Upon restoration of ship service power, the final bus may be returned automatically to the normal supply.

The emergency generator should continue to run without load until shut down manually.

The emergency switchboard should be in the same compartment as the emergency generator set and in a compartment adjacent to the storage battery room.

Indication should be provided in the machinery space, preferably at the principal propulsion control station, to indicate when the emergency generator is operating and when the emergency storage battery is being discharged.

7.3.6 Temporary emergency power A temporary power source provides emergency power in the interim period between the loss of main power and the establishment of emergency generator power.

Where a temporary source of emergency power is required, it should consist of energy storage suitably located for use in an emergency. Energy storage shall be in accordance with Clause 11. A converter may be used for supplying the temporary emergency bus for ac loads. The energy storage should have sufficient capacity and should be arranged to automatically supply the services listed in the following paragraphs of this subclause for 30 min (if they depend on an electrical source for their operation) in the event of failure of either the main or emergency source of power.

Where temporary emergency power is required, it shall be in accordance with this subclause. It shall feed the following designated loads: 

The lighting required in 7.3.7.



All essential internal communication equipment, fire detection, and associated alarm equipment.



All internal communication equipment required in an emergency.



Intermittent operation of the daylight signaling lamp, the ship’s whistle, the general alarm, the manual fire alarms, and all internal signals that are required in an emergency, unless they have an 48 Copyright © 2017 IEEE. All rights reserved.

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IEEE Std 45.1-2017 IEEE Recommended Practice for Electrical Installations on Shipboard—Design

independent supply from an accumulator battery suitably located for use in an emergency and sufficient for the period specified.

The temporary emergency bus should be supplied from the final emergency bus through an ABT device.

7.3.7 Temporary emergency circuits The emergency generator supplied power source should be supplemented by a temporary emergency source in accordance with 7.3.6. The capacity of the temporary emergency source should be determined by the connected load of all emergency circuits listed as follows: 

Navigation lights



Machinery space emergency lighting sufficient to permit performance of essential operations and the observation of all necessary gauges, gauge glasses, and instruments required under emergency conditions to facilitate restoration of service and to permit escape from all normally occupied spaces



Radio room lighting



Lighting (including low-level emergency egress lighting) for passenger and crew exits and passageways, including public spaces. Lighting should be adequate to permit passengers and crew to find their way to the embarkation deck. At least one light should be located in each section of each passageway and in each stairwell and stairwell exit on each deck. In no case should the distance between lights exceed 23 m.



At least one light in each berthing compartment accommodating 20 or more persons



One or more lights in the galley, pantry, steering gear room, space containing emergency power sources, chartroom, navigating bridge, all public spaces, and crew’s mess rooms and recreation rooms



Boat and embarkation deck lighting



Essential communication circuits among the navigating bridge, machinery spaces, and the steering gear room



Watertight door operating gear (if electric) and indicating system



Emergency loudspeaker or public address system



General or emergency alarm and the fire alarm systems



Gyro compass



Holding magnets for self-closing fire doors. To reduce battery capacity, holding magnets may be provided with a timing relay to cut off power if final emergency supply is not established or ship service supply restored within the maximum time provided for automatic cranking of the emergency generator prime mover, but not less than 2 min.

7.3.8 Final emergency circuits The following circuits should be connected to the final emergency bus: 

Navigation lights

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IEEE Std 45.1-2017 IEEE Recommended Practice for Electrical Installations on Shipboard—Design



Daylight signaling lamp



Whistle and siren control



Lifeboat flood lights (lighting in the vicinity of the lifeboats and the boat handling equipment, including lighting of the water at the sides of the vessel, should be sufficient to permit the complete operation of loading, lowering, and releasing of the lifeboats)



Emergency bilge pump, one fire pump, and if provided, one sprinkler pump



Other interior communication systems essential for the emergency operation of the vessel



Main and emergency radio (this is in addition to the separate storage battery source required by the regulatory agencies for emergency radio installations)



Navigation equipment required by the regulatory agencies



One steering gear system

7.3.9 Time factor for supply of emergency power The time factor for supplying emergency power, unless otherwise recommended, is as indicated in Table 5.

Table 5 —Minimum time requirement for emergency power Minimum time factor (hours) Passenger vessels

a

Ocean and coastwise Under 1600 gross tons 1600 gross tons and over Great Lakes Vessels navigating more than 4.8 kma offshore Vessels navigating not more than 4.8 kma offshore Ferries on runs over 1 h Ferries on runs under 1 h Great Lakes and rivers Ferries on runs over 1 h Ferries on runs less than 1 h Other vessels

3 statute mi

Cargo vessels

12 36

12 18

8 3

8 3

2 1 2 1 3

3

7.4 Safety IEEE Std 45.5 should be used to identify and incorporate design features that enable safe operation of the electric plant. Power system and component grounding is covered in Clause 25.

7.5 Power quality and harmonics Solid state devices such as motor controllers, computers, copiers, printers, and video display terminals may produce currents with frequency components other than the system frequency. Often these frequency components are harmonics of the system frequency, but they are not limited to harmonics. These nonsystem frequency currents may cause additional heating in motors, transformers, and cables. The sizing of protective devices should consider the non-system frequency current component. These currents may also

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cause EMI and RFI. EMI and RFI may result in interference with sensitive electronics equipment throughout the vessel.

Isolation, both physical and electrical, should be provided between portions of the power systems that supply loads sensitive to power quality and portions of the power systems that supply large numbers of devices that produce high levels of non-system frequency current components. Active or passive filters and shielded input isolation transformers should be used to minimize interference. Surge suppressors or filters should only be connected to power circuits on the secondary side of the equipment power input isolation transformers.

IEEE Std 519 provides additional recommendations.

8. Electrical power generation 8.1 General Shipboard electrical power generation systems contain one or more electrical generator sets that convert stored energy (typically a hydrocarbon fuel) to electrical power (ac or dc). Determining the number and power generation capability of power generation units is discussed in 7.1.

Electrical generator sets have traditionally consisted of a mechanical prime mover (diesel engine, gas turbine, or steam turbine) powered by a variety of fuels (e.g., distillate marine fuels, compressed natural gas, liquefied natural gas) coupled to a rotating ac or dc generator. In addition, new power generation technologies are available such as fuel cells that directly convert hydrogen 27 to dc electrical power. Power generation source and fuel selection depend on numerous ship design (including required performance), ship function, acquisition cost, and operating cost considerations as discussed in Clause 5.

Diesel-fueled prime movers are most practical for the majority of applications, but natural gas reciprocating engines or natural gas- or hydrocarbon liquid-fueled gas turbines may be utilized. Gasoline engines normally are unacceptable. Refer to 5.11 for marine environmental conditions and Clause 24 for material requirements.

All interior bolts, nuts, pins, screws, terminals, brush holder studs, springs, and other small parts shall be adequately protected against corrosion. Acceptable methods are corrosion-resistant materials or corrosionresistant treatments. Steel springs should be treated to resist moisture in such a manner as not to impair their spring quality.

8.2 Installation and location 8.2.1 General Electrical generating sets should be located in a dry, well ventilated place and shall be suitable for the area classification. They should not be installed in immediate proximity to water and steam piping (except for steam turbine prime movers) and should be protected from dripping liquids. Horizontal rotating machines should be installed with the shaft in a fore and aft direction. In cases where the shaft will be located athwartship, special consideration should be given to bearings and lubrication based on the ship design roll envelope.

27

Fuel cells are available with a “reformer,” that converts hydrocarbon fuel to hydrogen.

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IEEE Std 45.1-2017 IEEE Recommended Practice for Electrical Installations on Shipboard—Design

The location and installation of generating sets should allow access for inspection, maintenance, and repair.

The ship designer should ensure the machinery space arrangement provides the minimum maintenance and access space as defined by the generator set supplier. There should be at least 0.460 m between the set and surrounding objects to provide accessibility. Sufficient fore-aft access space should be provided to facilitate service and removal of the electrical generator’s rotor or armature.

Providing an enclosure or locating the unit in a space separate from other equipment or personnel can reduce the effects of prime mover noise.

The installation of fire detection systems are required for enclosed generating plants.

8.2.2 Air intakes Engine or turbine air intakes should be located in unclassified locations whenever possible to minimize the risk of ingestion of flammable mixtures. All diesel-fueled prime movers shall be equipped with an airintake shutoff valve or other suitable device that operates under emergency conditions that require primemover or generator shutdown. The following diesel-fueled engines are excepted: 

Cold-start engines (a diesel engine that starts a larger engine)



Fire pumps



Emergency generators



Blow out preventer (BOP) accumulator systems



Air supply to divers or confined entry personnel



Portable single-cylinder rig washers



Engines on escape capsules

8.2.3 Engine exhaust Engine or turbine exhaust outlets should be located in unclassified locations whenever possible to minimize the risk of ignition of flammable mixtures.

8.3 Generator set prime movers 8.3.1 Prime mover sizing Prime movers for rotating generator applications should have a minimum continuous shaft power (kW) output according to Equation (1):

kWmin =

PLoad

(1)

ηGen

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PLoad is the design electrical load (kW) ηGen is the generator efficiency

The efficiency of 25 kW and larger generators typically ranges from 88% to 94%.

All prime-mover ratings should be adjusted for the highest expected ambient temperatures and be de-rated for total system inlet and exhaust pressure losses. Generally, gas turbines are much more sensitive to these conditions.

Special consideration should be made when sizing prime movers for service where large motors or transformers will be started or energized across the line.

Prime mover capacity should be designed for the maximum load. This means that if one prime mover powers both a generator and auxiliary loads, it must have capacity for all output. The exception is when simultaneous operation of the generator and auxiliary load is not possible.

8.3.2 Lubrication All ship service and emergency generating sets should lubricate and operate satisfactorily without spilling oil, in a 10 s period, under the marine environmental conditions specified in 5.11. If the shaft is to be located athwartships, the manufacturer should be advised so that any special requirements for this orientation are addressed.

All prime movers for main power and ship service generating sets (not emergency sets) that depend on forced lubrication should be arranged to shut down automatically on loss of oil pressure. The shutting down of the prime mover should cause the tripping of the generator circuit breaker. An alarm system should be provided and arranged to function on low lubricating oil pressure.

8.3.3 Diesel engine generator set 8.3.3.1 Diesel engine prime mover Diesel engines are normally coupled directly to generators (i.e., no speed reducing gear box). Normal speed choices are dependent on desired frequency. The two common output frequencies are 60 Hz and 50 Hz. Table 6 shows the relationship between engine speed, generator pole count, and resulting output frequency.

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Table 6 —Prime mover versus generator pole-count Engine speed (rpm)

Generator poles

Output frequency (Hz)

600

10

50

720

10

60

750

8

50

900

8

60

1000

6

50

1200

6

60

1500

4

50

1800

4

60

3000

2

50

3600

2

60

For reduced maintenance and increased life, it is recommended that reciprocating type engines for continuous power installations be operated at 1200 rpm or less. For dc distribution systems, the prime mover speed is not relevant to electrical system operation.

Reciprocating type engines for standby (non-continuous) applications often are operated at speeds up to 1800 rpm.

8.3.3.2 Diesel engine-generator controls 8.3.3.2.1 Automatic shutdown controls Automatic controls should be provided to shut down the diesel engine when any of the following conditions occur: 

Low lube oil pressure



High jacket water temperature



Overspeed shutdowns should operate independently of governor controllers and should be set at no more than 115% of rated speed. The overspeed trip should also be equipped with a means for manual tripping.

Overvoltage for generators 500 kW and larger. It is recommended that either overvoltage shutdown controls be provided or that breakers be tripped and voltage regulators be de-energized.

Controls that shutdown the engine should also open the generator main circuit breaker. 

8.3.3.2.2 Optional shutdown controls Optional shutdown controls include the following:

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

Low lube oil level



Low jacket water level



Underspeed



Vibration 28



High lube oil temperature



Undervoltage 29



Underfrequency 30



Loss of excitation 31



Generator differential 32



Overfrequency 33

8.3.4 Gas turbine generator set 8.3.4.1 Gas turbine prime mover Gas turbine prime movers are typically aero-derivative cores adapted to provide mechanical drive output and operate in a maritime environment. Gas turbines are inherently high output speed devices and are coupled to the generator with a speed-reducing gear box, especially in the lower power output ratings.

Larger gas turbines are designed to operate at 3600 rpm and can be directly coupled to a two-pole generator to produce 60 Hz. 8.3.4.2 Gas turbine generator controls 8.3.4.2.1 Automatic shutdown controls Automatic controls should be provided to shut down gas turbines that are driving generators when any of the following conditions occur: 

Fail-to-start



High running exhaust temperature



High lube oil temperature



Low lube oil pressure



Underspeed



Overspeed



Vibration

For generators below 250 kW: Vibration shutdown controls are normally omitted.

Undervoltage shutdown controls normally are not used for generators under 500 kW. 30 Underfrequency shutdown controls normally are not used for generators under 500 kW. 31 Loss of excitation shutdown controls normally are not used for generators under 950 kW or units that are not to be paralleled.

32 Generator differential shutdown controls normally are not used for generators under 950 kW. 33 Overfrequency is normally used for generators rated 500 kW and above.

28 29

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Controls that shutdown the gas turbine should also open the generator main circuit breaker.

NOTE—Overvoltage for generators 500 kW and larger; it is recommended that either overvoltage shutdown controls be provided or that breakers be tripped and voltage regulators be de-energized.

8.3.4.2.2 Optional shut-down controls Optional shut-down controls include the following: 

Overfrequency: Overfrequency shutdown controls should be considered for generators larger than 500 kW.)



Loss of excitation: Loss of excitation shutdown controls should be considered for paralleled generators larger than 950 kW.



Generator differential: Generator differential shutdown controls should be considered for generators larger than 950 kW.



Lubrication: All ship service and emergency generating sets should lubricate and operate satisfactorily without spilling oil, in a 10 s period, under the conditions of inclination, roll, and pitch specified in 5.11. If the shaft is to be located athwartships, the manufacturer should be advised so that any special requirements for this orientation are addressed.

8.3.5 Steam turbine prime mover Though not as common as in the past, some ships use a heat source to generate steam, which is used to provide the energy to power steam turbines for power generation. Similar to gas turbines, depending on the steam turbine design speed, a speed reducing gear box is used to couple the steam turbine to the generator to produce the desired output frequency.

8.3.6 Prime mover speed control system (governor) 8.3.6.1 General The prime-mover speed control system (e.g., governor) performance is critical to satisfactory electric power generation in terms of constant frequency, response to load changes, and the ability to operate in parallel with other generators.

The steady state speed variation should not exceed 5% (e.g., 3 Hz for a 60-Hz machine) of rated speed at any load condition.

Each prime mover should be under control of a governor capable of limiting the speed, when full load is suddenly removed, to a maximum of 110% of the rated speed. It is recommended that the speed variation be limited to 5% or less of the overspeed trip setting.

The prime mover and regulating governor should also limit the momentary speed variation to the values indicated in this subclause. The speed should return to within 1% of the final steady state speed in a maximum of 5 s or as set by the limits specified in Table 7.

For emergency generators, the prime mover and regulating governor shall be capable of assuming the sum total of all emergency loads upon closure to the emergency bus. The response time and speed deviation shall be within the tolerances indicated in Table 7.

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Table 7 —Response time and speed deviation requirements Load (%) 0 – 50 50 – 0 50 – 100 100 – 50

Response time (s) 5.0 5.0 5.0 5.0

Speed deviation (%) 10 10 10 10

Generator sets should be capable of operating successfully in parallel when the following conditions are met: 

Operating load is between 50% and 100% of the sum of the rated loads on all generators



The load (kW) on the largest generator does not differ from the others by more than ±15% of the rated output



The load (kW) on the largest generator does not differ from the others by more than 25% of the rated output of any individual generator from its proportionate share

The starting point for the determination of the successful load distribution requirements is to be at 75% load with each generator carrying its proportionate load.

8.3.6.2 Mechanical governors The mechanical-type governor has the slowest response to load changes and provides the least accuracy in speed control and, therefore, should be considered only for small generator units in which close frequency control is not required. It is not suitable for continuous parallel operation.

8.3.6.3 Hydraulic-mechanical governors The hydraulic-mechanical type governor provides fast response to load changes and close speed control.

This governor can be equipped with an electric motor to allow for remote speed control. The governor is adjustable to operate in either isochronous (constant speed) or droop (speed decreases with load) mode, thus, allowing its use for continuous parallel generator operation.

8.3.6.4 Electronic governors The electronic governor system provides the highest accuracy and fastest response. It senses engine speed from either the frequency of the generated voltage or a magnetic pick-up installed on the engine.

Automatic load sharing control and automatic synchronization can be incorporated with this type of governor and is desirable for multi-unit continuous parallel operation. Generators operating in parallel should share the load in proportion to their rating. Units of different sizes in continuous parallel operation require detailed engineering analysis.

8.3.7 Engine starters Electric, pneumatic, and hydraulic motor starters are available for both reciprocating engines and small- to medium-sized gas turbines. All three types of starters may be safely used in classified locations, provided that electric starter systems are approved for the area. Electric and compressed air motor starting systems

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IEEE Std 45.1-2017 IEEE Recommended Practice for Electrical Installations on Shipboard—Design

are the most common used in reciprocating engines. It is recommended that engine starting batteries not be used for control system power because of a significant voltage drop during cranking.

8.3.8 Shutdown valve A fail-closed fuel shutdown valve should be provided on natural gas-fueled prime movers. On mobile offshore drilling units (MODUs), an air-intake shutoff valve should be installed on diesel-fueled prime movers. These valves would be operated under emergency conditions that require prime mover/generator shutdown. Other requirements for natural gas-fueled systems shall be in accordance with IACS UR M59.

8.3.9 Ignition systems For prime movers installed in classified locations, ignition systems should be designed and installed to minimize the possibility of the systems being a source of ignition.

All engines with electrical ignition systems should be equipped with a system designed to minimize the potential for the release of sufficient electrical energy to cause ignition of an external, ignitable mixture.

Systems verified by a Nationally Recognized Testing Laboratory (NRTL) as suitable for classified locations are recommended. Breaker point distributor-type ignition systems should not be used in classified locations. All wiring should be minimized in length; kept in good condition, clean, clear of hot or rubbing objects; suitable for the voltage and current; and suitable for the ambient temperature.

8.3.10 Special considerations The minimum power requirement is of special importance when diesel-engine prime movers are used to avoid excessive maintenance due to continuous operation of engines at light loads for long time periods.

8.4 Generators 8.4.1 General Electric generators should be designed to perform in accordance with NEMA MG-1, IEEE Std C50, or IEC 60034. Generators are normally three-phase, except for small systems that serve only single-phase loads. For ships with dc power generation and distribution system, an ac generator may be used with either an integral rectifier or a stand-alone rectifier.

Power takeoff generators may be connected via a clutch that will enable the generator to be disconnected from the propeller shaft or propulsion reduction gear, depending on where it is mechanically connected. In these applications, the generator rotational speed is slaved to the shaft speed, which is often variable depending on ship’s speed. The generator’s variable frequency output will have to be electronically conditioned to provide appropriate voltage and frequency characteristics required by the distribution system.

8.4.2 Selection and sizing Generators are designed to carry full nameplate rating in kW provided the nameplate kVA rating is not exceeded. Air-cooled generators normally are rated for 0.8 power factor (power factor = kW/kVA) at sea level and 50 °C ambient temperature when located in machinery spaces or other spaces that could achieve

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IEEE Std 45.1-2017 IEEE Recommended Practice for Electrical Installations on Shipboard—Design

this ambient temperature. Where generators are totally enclosed and water cooled (TEWAC), the generator should be designed for an inlet water temperature of 32 °C. For inlet temperatures exceeding 32 °C, the generator may be specifically designed for the higher inlet temperature or be derated from the 32 °C rating in accordance with manufacturer’s recommendation. Generators should be properly rated for the ambient temperature in which they operate. See 5.11 for the applicable ambient temperature requirements. Special consideration shall be given for generators installed in unit enclosures for higher than normal ambient conditions.

In determining the number and capacities of generating sets to be provided for a vessel, careful consideration should be given to the normal and maximum load demands (i.e., load analysis) as well as for the safe and efficient operation of the vessel when at sea and in port. The vessel must have at least two generating sources. For ships, the number and ratings of the main generating sets should be sufficient to provide one spare generating set (one set not in operation) at all times to service the essential and habitable loads. For MODUs, with the largest generator offline, the combined capacity of the remaining generators must be sufficient to provide normal (non-drilling) load demands.

For vessels propelled by electric power and having two or more constant-voltage, constant-frequency, main power generators, the ship service electric power may be derived from this source and additional ship service generators need not be installed, provided that with one main power generator out of service, a speed of 7 knots or one-half of the design speed (whichever is the lesser) can be maintained. The combined normal capacity of the operating generating sets should be at least equal to the maximum peak load at sea.

If the peak load and its duration is within the limits of the specified overload capacity of the generating sets, it is not necessary to have the combined normal capacity equal to the maximum peak load.

A generator driven by a main propulsion unit (shaft generator) that is intended to operate at constant speed (e.g., a system in which vessel speed and direction are controlled only by varying propeller pitch) may be considered to be one of the required ship service generators, provided it is able to supply the required power even with the vessel stopped.

Shaft generator installations that do not comply with the criteria given in this subclause may be fitted, in addition to the above-required generators, provided that an alternative source of electrical power having a capacity sufficient for the loads necessary for propulsion and safety of the vessel, can be brought on line automatically within 45 s when the shaft generator fails to maintain voltage and frequency within prescribed limits.

If shaft generators are employed at sea, where the shaft speed is not constant, then suitable means of control should be provided so that the speed of the main engine does not drop below the shaft generator critical operating speed until an auxiliary generator is automatically started. This will enable a load transfer to be made to prevent a blackout while not impairing the ability of the vessel to be maneuvered from the navigating bridge.

In selecting the capacity of an ac generating plant, particular attention should be given to the starting current of ac motors supplied by the system. With one generator held in reserve and with the remaining generator set(s) carrying the minimum load necessary for the safe operation of the ship, the voltage sag resulting from the starting current of the largest motor on the system should not cause any motor already running to stall or control equipment to drop out. It is recommended that this analysis be performed when the total horsepower of the motors capable of being started simultaneously exceeds 20% of the generator nameplate kVA rating. The generator prime-mover rating may also need to be increased to be able to accelerate motor(s) to rated speed. Techniques such as soft starting (e.g., reduced voltage autotransformer starters, electronic soft starters, and variable frequency drives) may be utilized to reduce the required capacity of generators when motor starting is of concern.

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8.4.3 Generator design Revolving field, brushless-type generators are recommended to eliminate all arcing contacts and to reduce maintenance requirements. The use of permanent magnet exciters should be considered. If a residual magnetism type exciter is used, it should have the capability of voltage buildup after two months without operation. It is recommended that generators have a design temperature rise of 80 °C, by resistance, (NEMA Class B), but be constructed with a minimum of NEMA Class F insulation to provide optimum balance between initial cost and long-life operations. See 5.11 for the applicable ambient temperature requirements.

Generators normally are designed for 40 °C ambient temperatures, and thus, they should be derated in accordance with manufacturer’s recommendations if operated in higher ambient temperatures.

Design temperature ratings for generators are based on the maximum insulation system temperature at the hottest spot, as shown in Table 8. This is referred to as the total temperature rating and consists of the ambient temperature plus a temperature rise plus hot spot allowance.

Table 8 —NEMA design class temperature rating NEMA design class B F H

Total temperature rating (°C) 130 155 180

It is recommended that generators have a NEMA design B total temperature rating and rise in accordance with Table 9 (at the most ambient temperatures) and be constructed with a minimum of NEMA Class F insulation to provide optimum balance between initial cost and long-life operations. See 5.11 for the applicable ambient temperature requirements.

Table 9 —Temperature ratings of generators Machine part All windings

Method of measurement Resistance

Temperature (°C) Maximum rise = 130 – 20 – ambient

Windings < 1563 kVA

RTD

Maximum rise = 130 – 10 – ambient

Windings > 1563 kVA < 7 kV

RTD

Maximum rise = 130 – 5 – ambient

RTD

Maximum rise = 130 – ambient

> 7 kV

Field winding Resistance RTD = resistance temperature detection

Maximum rise = 130 – 5 – ambient

Ambient is defined as the temperature of the air entering the machine. The limits indicated above are for rises according to NEMA Class B and are used in the interest of personnel safety. Part of the path for removing heat from the windings is via conduction and convection to the exterior surface of the stator. This surface will normally reach temperatures of 45 °C to 50 °C higher than the incoming air when the machine is operated at loads resulting in the Class B rise.

Generators should be designed and specified on total temperature rating, including ambient temperature, temperature rise, and any hot spot allowance. The user should provide the necessary information to the manufacturer so the generator can be properly designed. In some cases, a generator based on the industry standard 40 °C ambient temperature may be used or specified. In these cases, the machine should be derated in accordance with manufacturer’s recommendations for operating at higher ambient temperatures.

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The rotor insulation shall have a Class F (155 °C) total temperature rating and operate at a Class B temperature rise over the ambient temperature specified for the location (i.e., 45 °C or 50 °C). For longer rotor life, a Class H (180 °C) insulation system operated at a Class B rise could be considered.

For generators requiring peak and peak reserve capabilities, the total temperature allowance may go up to the next class rating. For instance, the Class B maximum temperature would be 155 °C and Class F would be 180 °C. Generator windings should be designed with quality insulation materials that are resistant to oil, water, and salt-laden atmospheres.

It is recommended that all form-wound coils for ac generators utilize vacuum-pressure impregnated solventless epoxy insulation systems. After each vacuum-pressure-impregnation (VPI) cycle, stators should undergo a rotating cure process. It is recommended that after final cure, the windings shall be given an antifungal treatment. If verification of the VPI epoxy resin and chemical polymerization (gel time) is required, it should be done in accordance with ASTM D247 I. Generators installed in the following locations shall have minimum requirements and ratings as shown: 

For voltages less than 1000 V, generators located in enclosed spaces that prevent direct exposure to outdoor conditions, open drip proof or minimum IP22 enclosures may be used.

For voltages equal to or greater than 1000 V, generators located in enclosed spaces that prevent direct exposure to outdoor conditions, WPI, WPII, or minimum IP 23 enclosures may be used. The terminal boxes require NEMA 3 or IP44 protection.

Generators exposed to weather should be totally enclosed fan cooled (TEFC), totally enclosed with either air to air (TEAAC), totally enclosed air to water (TEWAC), or provided with an IP56 enclosure. Where TEWAC enclosures are used on generators, they shall be of double tube construction and be equipped with leak detection. 

The generator winding shall be capable of withstanding, without mechanical damage, for 30 s, a bolted three-phase and phase-to-ground short-circuit at its terminals when operating at the highest capability kVA, rated power factor, and at 5% overvoltage.

The windings shall also be capable of withstanding, without damage, any other short-circuit at its terminals of 30 s duration or less, provided the machine phase currents under fault conditions are such that the negative sequence current (I2) expressed in terms of per unit stator current at highest capability kVA, and the duration of the fault in seconds (t) are limited to values, which given by the integrated product of (I2)×(I2)×(t) (negative phase sequence current squared times time), is equal to or less than 40.

The generator shall be capable of withstanding for 10 s, without damage, an excitation level in the field winding corresponding to a fault current of 300% of design full load current in addition to associated shortcircuit heating and forces in the armature winding.

Generators shall be capable of withstanding the following without damage: 10% overload for 2 h and 50% overload for 30 s.

Special evaluation of winding geometry must be considered if dissimilar machines are to be paralleled.

Equipment manufacturers should be consulted for equipment compatibility.

8.4.4 Terminal arrangements and incoming cables Generators should be provided with silver- or tin-plated copper fixed terminals used for connection of incoming cable and lugs or provided with copper terminal leads suitably secured to the generator frame.

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be supplied with suitable provisions for NEMA or IEC lugs with a minimum of two holes. Terminal lugs shall be suitable for the conductor size and temperature rating of the incoming cables. It may be necessary to provide a transition bus to accommodate metric and ANSI/NEMA dimensions.

Terminal boxes should be of sufficient size to accommodate the generator leads and terminals without crowding or exceeding the bend radius of the leads. Where shielded cables are used on generation voltages of 3 kV and higher, sufficient straight space shall be provided between the point of cable entrance and terminals for installation of stress cones. Space should also be provided for current transformers used for differential, other protection, or metering. Additional space may be necessary for bus bars and other means of interconnection of neutral leads for six lead machines. Each box should be of adequate mechanical strength and rigidity to protect the contents and to prevent distortion under all normal conditions of service.

Cables of differing voltage should not be included in the same terminal box unless each voltage is clearly and permanently identified and effective barriers provided within the enclosure to separate each voltage.

Separate junction boxes should be provided for instrumentation devices such as stator winding RTDs or generator-bearing vibration sensors.

The conductors from each generator to any switchboard should be sized for no less than 115% of the generator continuous rating and 115% above the overload rating when machines are specified with overload ratings. Thermal limits of the conductor and terminal devices, including the generator circuit breaker, shall not be exceeded under the ambient temperature specified.

8.4.5 Heaters Means should be provided to prevent the absorption of moisture by machine windings and condensation of moisture onto the machine’s internal surfaces. These means should be automatically energized when the generator is stopped or at any time that the temperature of the windings or metal parts of the generator are lower than the ambient temperature.

8.4.6 Nameplates Generators should be supplied with nameplates of corrosion-resistant material marked with the following information: 

Name of manufacturer



Kilovoltamperes or kilowatts



Manufacturer’s type and frame designation



Manufacturer’s serial number



Output: in kilovoltamperes or kilowatts



Voltage rating



Current rating



Rated power factor



Full load amperes



Frequency



Number of phases



Rated temperature rise 62 Copyright © 2017 IEEE. All rights reserved.

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IEEE Std 45.1-2017 IEEE Recommended Practice for Electrical Installations on Shipboard—Design



Insulation class



Service factor (or intermittent duty rating)



Ambient temperature rating



Full load speed in revolutions per minute



For anti-friction bearings, the manufacturer and model number



For flood-lubricated bearings, the oil rated in liters per minute (gallons per minute)



For pressure-lubricated bearings, the oil pressure required, in Newtons per square millimeter (pounds per square inch gauge)



Rated main field voltage



Rated main field current

8.4.7 Voltage regulation At least one voltage regulator shall be provided for each generator. Voltage regulation should be automatic and should function under steady state load conditions between 0% and 100% load at all power factors that can occur in normal use. Voltage regulators should be capable of maintaining the voltage within the range of 97.5% to 102.5% of the rated voltage. A means of adjustment should be provided for the voltage regulator circuit. Voltage regulators should be capable of withstanding shipboard conditions and should be designed to be unaffected by normal machinery space vibration.

Solid state voltage regulators are recommended for high reliability, long life, fast response, and stable regulation. Regulator systems should be protected from underfrequency conditions. It is recommended that voltage regulators for machines rated in excess of 150 kW be provided with underfrequency and overvoltage sensors for protection of the voltage regulators.

Under motor starting or short-circuit conditions, the generator and voltage regulator together with the prime mover and excitation system should be capable of maintaining short-circuit current of such magnitude and duration as required to properly actuate the associated electrical protective devices. This shall be achieved with a value of than not less than 300% of generator full-load current for a duration of 2 s, or of such additional magnitude and duration as required to properly actuate the associated protective devices.

For single-generator operation (no reactive droop compensation), the steady state voltage for any increasing or decreasing load between zero and full load at rated power factor under steady state operation should not vary at any point more than ±2.5% of rated generator voltage. For multiple units in parallel, a means should be provided to automatically and proportionately divide the reactive power between the units in operation.

Under transient conditions, when the generator is driven at rated speed at its rated voltage, and is subjected to a sudden change of symmetrical load within the limits of specified current and power factor, the voltage should not fall below 80% nor exceed 120% of the rated voltage. The voltage should then be restored to within ±2.5% of the rated voltage in not more than 1.5 s.

In the absence of precise information concerning the maximum values of the sudden loads, the following conditions should be assumed: 150% of rated current with a power factor of between 0.4 lagging and zero to be applied with the generator running at no-load, and then removed after steady state conditions have been reached.

For two or more generators with reactive droop compensation, the reactive droop compensation should be adjusted for a voltage droop of no more than 4% of rated voltage for a generator. The system performance should then be such that the average curve drawn through a plot of the steady state voltage vs. load for any 63 Copyright © 2017 IEEE. All rights reserved.

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IEEE Std 45.1-2017 IEEE Recommended Practice for Electrical Installations on Shipboard—Design

increasing or decreasing load between zero and full load at rated power factor, droops no more than 4% of rated voltage. No recorded point varies more than ±1% of rated generator voltage from the average curve.

Isochronous operation of a single generator operating alone is acceptable. However, where two or more generators are arranged to operate in parallel, it is recommended that isochronous kilowatt load sharing governors and voltage regulation with reactive differential compensation capabilities be provided. Care should be taken if operating machines in parallel to ensure that the system minimum load does not decrease and cause a reverse power condition.

If voltage regulators for two or more generators are installed in the switchboard and located in the same section, a physical barrier should be installed to isolate the regulators and their auxiliary devices.

Where power electronic devices (such as variable frequency drives, soft starters, and switching power supplies) create measurable waveform distortions (harmonics), means should be taken to avoid malfunction of the voltage regulator, e.g., by conditioning of measurement inputs by means of effective passive filters.

Power supplies and voltage sensing leads for voltage regulators should be taken from the generator side of the generator circuit breaker. Normally, voltage sensing leads should not be protected by an overcurrent protection device. If short-circuit protection is provided for the voltage sensing leads, this short-circuit protection should be set at no less than 500% of the transformer rating or interconnecting wiring ampacity, whichever is less. It is recommended that a means be provided to disconnect the voltage regulator from its source of power.

8.4.8 Generator metering and protection See IEEE Std 45.7 for recommended practices for generator metering and protection.

9. Power distribution 9.1 General Shipboard electrical systems may have distribution systems for power, lighting, interior communications, and control systems. Electrical systems can be fed from the ship service generators, emergency generators, or a combination of both. Power for normal lighting should be distributed from the ship’s service switchboard. Power for emergency lighting, interior communications, and electronics systems feeders should be distributed from the emergency switchboard. Alternatively, interior communications and electronics systems providing vital services may be supplied utilizing dual feeders via an ABT system from the ship’s service and emergency switchboards.

Where more than one power source (generator and or shore power) is available and the sources are not intended to operate in parallel, a mechanical or electrical interlock to prevent paralleling should be provided.

9.2 Circuit elements All normal current-carrying elements of electrical power supply circuits should be specifically intended for that purpose only. Ship structure should not be used as a normal current-carrying conductor for the electrical power supply distribution systems.

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IEEE Std 45.1-2017 IEEE Recommended Practice for Electrical Installations on Shipboard—Design

9.3 Shore power If a shore power connection is provided, a connection box (see 9.10.7) should be installed in a location convenient for the reception of the cables from the shore. The shore power system should include shore power circuit breaker(s), shore power available indicating light(s), and a phase sequence or phase rotation detection device. Cables from the connection box to the ship service switchboard should be permanently installed. One of the switchboard voltmeters should have the capability to indicate the shore power voltage.

9.4 Demand factors 9.4.1 General Feeder and branch circuit conductors should be sized for 100% of their connected load, except as given in 9.4.2., 9.4.3, and 9.4.4. Conductor sizing should be based on published ampacity ratings for the conductors, with applicable derating factors applied for ambient temperature, raceway configuration, and so on. See IEEE Std 45.8 for additional information. Conductors less than 15 AWG (1.5 mm² for IEC wiring systems; see 1.4) should not be used in any branch circuit.

9.4.2 Lighting, interior communications, and electronics circuits Conductors for lighting, communications, and electronics circuits should be sized for the total connected load, including not less than 180 VA for each duplex receptacle. The connected load should include 50% of the rating of spare circuits on switchboards or load centers and the average active circuit load for the spare circuits on distribution panels. Loads for circuits supplying electric discharge-type lamps should be computed on the basis of ballast input current. Feeders for circuits including cargo flood lighting receptacles should be calculated on the basis of expected load, but not less than 300 W per receptacle.

9.4.3 Galley circuits Conductors for galley equipment should be sized on the basis of 100% demand factor for the first 50 kW of connected load and 65% of the connected load in excess of 50 kW. 9.4.4 Individual and multiple motor circuits Except as recommended in 9.8.3, conductors supplying an individual motor should have a continuous current-carrying capacity equal to 125% of the motor nameplate rating. Conductors supplying more than one motor should have a continuous current-carrying capacity equal to 125% of the largest motor plus the sum of the nameplate ratings of all other motors supplied, including 50% of the rating of spare switches on the distribution unit.

Conductors supplying a group of three or more workshop tool motors should have a continuous current carrying capacity equal to 125% of the nameplate rating of the largest motor plus 50% of the sum of the nameplate ratings of all other motors of this group.

Conductors supplying two or more motors driving deck cargo winches or cargo elevators should have a continuous current-carrying capacity equal to 125% of the largest motor plus 50% of the sum of the nameplate ratings of all other motors.

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IEEE Std 45.1-2017 IEEE Recommended Practice for Electrical Installations on Shipboard—Design

Conductors supplying two or more motors driving cargo cranes should have a continuous current-carrying capacity equal to 125% of the largest motor plus 50% of the sum of the nameplate rating of all other motors.

Where the conductor supplies two or more motors associated with a single crane, the current-carrying capacity should be equal to 125% of the largest motor plus 45% of the sum of the nameplate rating of the other motors.

9.4.5 Other circuits Conductors between separate ship service switchboards having connected generators (ship service generator switchboards) should be sized on the basis of 75% of the switchboard having the greatest generating capacity. The drop in voltage from each generator to its switchboard should not exceed 1%, and the drop in voltage between switchboards should not exceed 2%.

Conductors between ships service switchboards and the emergency switchboard should be sized on the basis of the maximum operating load of the emergency switchboard or 115% of the emergency generator capacity, whichever is larger.

Conductors from storage batteries to the point of distribution should be sized for the maximum continuous charge or discharge rate, whichever is greater. Battery conductors for heavy duty applications, such as diesel starting, should be sized for 125% of maximum-rated battery discharge.

9.5 Voltage drop 9.5.1 General For all distribution circuits, unless stated otherwise, the combined maximum voltage drop from the ship’s service switchboard to any point in the system should not exceed 5%.

9.5.2 Feeder and branch circuit continuity Except as permitted in 9.5.2 and 9.5.3, each feeder and branch circuit supplying a single energy-consuming appliance should be continuous and uniform in size throughout its length. In instances of feeders of large size and exceptional length, junction boxes or splices may be used for ease of installation. When authorized by the appropriate regulatory agency, splices or junction boxes may be permitted to repair damaged cable (see IEEE Std 45.8).

9.5.3 Feeder connections Where a feeder supplies more than one distribution panel, it may be continuous from the switchboard to the farthest panel or it may be interrupted at any intermediate panel. If the bus bars of any distribution panel carry “through” load, the size of the buses should be suitable for the total current. The size of feeder conductors will ordinarily be uniform for the total length but may be reduced at any intermediate distribution panel, provided that the smallest section of the feeder is protected by the overload device at the distribution switchboard.

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9.6 Lighting distribution 9.6.1 Lights controlled from the navigating bridge A separate feeder should be provided for all lights supplied from the emergency switchboard and located in or controlled from the navigating bridge. On passenger vessels, two feeders may be provided: one from the temporary emergency (storage battery) bus and one from the final emergency bus. For the feeder supplying navigation lights (from the temporary emergency bus, if provided), the rating of the cable and of the fuse or circuit breaker on the emergency switchboard should be not less than 20 A or not less than 125% of connected load, including allowance for spare circuits, whichever is greater.

One or more distribution panels may be served by the feeders described in this subclause. Through feed, without switch or overcurrent protection, should be provided for the navigation light panel. For all other lights, including any navigation or signal lights not supplied by the navigation light panel, branch circuits, each with a fused-switch or circuit breaker, should be provided.

Floodlights for lifeboat launching should be supplied by branch circuits from the navigating bridge emergency panel, or it may be supplied directly from the emergency system through local lighting contactors controlled from the navigating bridge. Lighting for adjacent launching stations should be supplied by different branch circuits.

One four-conductor, or two-conductor, branch circuit cables should be provided from the navigation light indicator panel for each two-lamp navigation light fixture. Each four-conductor branch circuit cable from the indicator panel should terminate in a waterproof two-circuit, two-gang receptacle located adjacent to the running light. If two-conductor branch circuit cables are provided, each cable should terminate in a singlegang waterproof receptacle. The receptacles should be of the grounding type. Two three-conductor portable cables should be provided for each two-lamp fixture, and each should be fitted with a three-pole plug.

9.6.2 Machinery space lighting Separate lighting feeders should be installed for each main and auxiliary machinery space. These feeders should not supply fixtures outside the machinery spaces, other than storerooms opening into these spaces.

The number and size of the feeders and distribution panels should be determined by the number of fixtures and the extent of the spaces covered. It is recommended that alternate groups of fixtures within these spaces be so arranged that the failure of any one circuit will not leave these spaces in darkness.

9.6.3 Cargo space lighting Separate feeders should be installed for all cargo lighting. The distribution panels should be located outside of the cargo spaces. Receptacles in cargo spaces should be connected neither to feeders that are used for lighting nor to circuits required for the underway operation of the vessel.

9.6.4 Accommodation space lighting For vessels provided with structural fire boundary bulkheads forming fire zones, it is recommended that at least two separate feeders be provided exclusively for each vertical zone between two fire boundary bulkheads. These feeders may serve all decks within the zone. One of these may be the emergency lighting feeder. The supply of lights in all passageways and public spaces and in any berthing compartment accommodating more than 25 persons should be divided between two feeders so that if either fails, there will be sufficient light to prevent panic and to permit people to find their way to the open deck. The two

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IEEE Std 45.1-2017 IEEE Recommended Practice for Electrical Installations on Shipboard—Design

feeders serving one compartment should be separated as widely as practicable to minimize the possibility of damage to both from a fire or other casualty.

On passenger vessels, electric service to each passenger stateroom should be supplied by at least two separate branch circuits connected to the general lighting system. The lighting should be so divided that in the event of failure of one branch circuit, there will be sufficient light to permit use of the space.

9.6.5 Two-wire device connections In grounded systems, the shell of all lamp holders should be connected to the grounded conductor, and all single-pole switches should be in the ungrounded conductor. In two-wire ungrounded systems, the color of conductors connected to single-pole switches should be uniform throughout the system.

9.7 Delivery power feeders In general, power feeders for cargo elevators, cargo cranes, and cargo winches that should be disconnected when the vessel is underway should not be used to supply ventilation fans, heaters, drainage pump motors, or any apparatus required for the ship’s operation.

Separate feeders from switchboards should be run for main and auxiliary machinery space loads, motors for cargo-handling gear, steering gear, navigation and electronics loads, searchlights, and ventilation and air conditioning loads. Cargo ventilation fans, machinery space ventilation fans, and fans for ventilation of accommodations should not be supplied from the same feeder.

The steering gear motors should be supplied from two different circuits and, where practical, from two different switchboards or switchboard bus sections. These circuits should be widely separated to minimize failure of both feeders due to collision, fire, or other casualty. Both feeders may be connected to the ship service switchboard, or where required by the regulatory agencies, one feeder may be connected to the ship service switchboard and one to the emergency switchboard. Each circuit should have a continuous current carrying capacity of not less than 125% of the rating of the motor or motors simultaneously operated. The special requirements for electrical power distribution to steering gear systems are described in 16.5.2.

In order to prevent the spread of fire, arrangements should be made to permit stopping all ventilation fans, fuel oil pumps, and lube oil transfer pumps from a central point. For further details, see IEEE Std 45.2.

Separate feeders and distribution panels should be provided for air heaters when they are used extensively.

Separate feeders and distribution panels should be provided for galleys equipped with electric ranges, ovens, and other electric apparatus.

9.8 Branch circuits 9.8.1 General The branch circuit conductors should not be less than No. 15 AWG (1.5 mm² for IEC wiring systems; see 1.4). Cable types and sizes (refer to IEEE Std 45.8) should be selected for compatibility with all local environmental conditions throughout the length and voltage drop limitations of this subclause. Each branch circuit should be provided with overcurrent protection in accordance with 21.3, except as otherwise indicated. The maximum connected load should neither exceed the rated current-carrying capacity of the cable nor 80% of the overcurrent protective device setting or rating.

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9.8.2 Heating and cooking equipment Generally, a separate branch circuit should be provided for each electric heater. An individual heater or a group of heaters may be supplied from a lighting or power distribution panel, depending on the required voltage.

For ranges, bake ovens, and similar galley units in which self-contained or locally mounted protective devices are provided for each individually controlled heating element, only one branch circuit need be provided for each assembled unit.

9.8.3 Motors A separate branch circuit should be provided for each fixed motor having a full-load current rating of 6 A or more, and the conductors should have a carrying capacity of not less than 1.25x the motor full-load current rating. Any branch circuit conductor should have a cross-section no less than that corresponding to 20 AWG 15 (1.5 mm2 for IEC wiring systems).

9.8.4 Fixed appliances Fixed appliances may be supplied by branch circuits from galley, lighting, or power distribution panels according to availability. However, no lighting or receptacle outlets should be served by the same branch circuits serving fixed appliances. Indicating lights in or on any appliance may be considered as being protected by the branch circuit fuse or circuit breaker.

9.8.5 Receptacles Receptacles installed on a 15 A branch circuit protective device, shall be rated 15 A, maximum. For 20 A circuits containing more than one receptacle, 15 A rated receptacles may be used. Circuits of 30 A or higher and containing more than one receptacle should use receptacles rated at no less than the circuit rating. Receptacles should not supply a total load of portable and stationary equipment in excess of 80% of the branch circuit protective device rating.

Receptacle outlets in passages and public spaces for vacuum cleaners, in galleys for motor driven scrubbers, in laundries for pressing irons, in shops for special portable motor-driven tools, or for any similar special application should be of the heavy duty type and on separate branch circuits, with no other outlets connected. Receptacle outlets in machinery spaces should be on separate branch circuits supplied from lighting distribution panels. In auxiliary machinery compartments where there are not more than two receptacles, the receptacles may be connected to a lighting distribution circuit.

Where portable motors that operate on other than the shipâ&#x20AC;&#x2122;s normal lighting voltage are used, the receptacles voltage should be permanently identified. The receptacles should be of a type that will not permit attaching equipment for which the voltage is unsuitable.

9.8.6 Lighting Lighting branch circuits should be single-phase circuits supplied from panel boards and provided with overcurrent protection devices rated at 15 A, 20 A, 25 A, or 30 A. On ungrounded systems, switches and overcurrent protective devices shall be two-pole. On grounded systems, single-pole switches and overcurrent protective devices are acceptable.

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IEEE Std 45.1-2017 IEEE Recommended Practice for Electrical Installations on Shipboard—Design

Three-phase lighting branch circuits may be used for special purposes such as clusters of floodlights and large multi-lamp lighting fixtures. Switches for such circuits should open all conductors of the circuit.

AC general-use snap switches should have a minimum rating equal to the load controlled. ac/dc general-use snap switches for use with tungsten filament lamp loads should have a minimum rating equal to the load controlled and the inrush current. Lighting fixtures for use on 25 A and 30 A circuits should be heavy duty type rated not less than 750 W (1 hp). The total single-phase branch circuit load should be balanced as far as practicable at the connection point to the three-phase system. Any imbalance should not exceed 15%.

In general, motors larger than 190 W should not be connected to lighting circuits.

9.9 Circuit designation All electrical circuits, including those for power, lighting, interior communications, control, and electronics, are typically identified in the appropriate documentation and on equipment labeling, such as nameplates, cable tags, wire markers, and so on, by a traditional system designation. These designations use a designation prefix, as follows in Table 10.

Table 10 —Traditional system designation prefix Type

Designation prefix

Ship service power

P

Emergency power

EP

Propulsion power

PP

Shore power

SP

Special frequency power

SFP

Lighting

L

Emergency lighting

EL

Degaussing

D

Cathodic protection

CPS

Interior communication

C

Control

K

Electronics

R

Table 11 lists systems and system designations that should be used, and may be modified to suit particular applications as shown in Table 10.

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IEEE Std 45.1-2017 IEEE Recommended Practice for Electrical Installations on Shipboard—Design

Table 11 —System designation System

Designation

Announcing: Docking

C-5MC

Announcing: General

C-1MC

Announcing: Integrated

C-MC

Announcing: Loudhailer

C-6MC

Announcing: Talk back

C-9MC

Auxiliary machinery remote control

K-AC

Boiler combustion control

K-SX

Boiler water level control

K-BL

Boiler water level alarm

C-1TD

Call bells

C-A

Central alarm and monitoring

C-AM

CO2 release alarm

C-CO

Cooling water high-temperature alarm

C-EW

Echo depth sounder

R-SS

Electric clocks

C-CE

Electric door control (other than for watertight doors)

C-DE

Electric plant control and monitoring

K-EC

Emergency generator set control and indication

K-EG

Engine order telegraph

C-MB

Feed water low-level alarm

C-2TD

Fire detection and alarm

C-F

Fire door release

C-FR

Flooding alarm

C-FD

Fog alarm

C-FB

Fuel oil filling alarm

C-3TD

Fuel oil tank high-level alarm

C-4TD

General alarm

C-G

Gyro compass

C-LC

Helm angle indicator

C-LH

Hospital and nursing call

C-AN

Integrated navigation

C-IN

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System

Designation

Lubricating oil low-level alarm

C-EL

Lubricating oil low-pressure alarm

C-EC

Main generator set local control and indication

K-PG

Propulsion diesel local control and indication

K-PD

Propulsion motor local control and indication

K-PM

Propulsion system remote control

K-PC

Propulsion turbine local control and indication

K-PT

Pyrometer

C-PB

Radar, navigation

R-RN

Radio antenna

R-RA

Radio direction finder

R-RD

Radio GMDSS

R-GA

Radio receiver

R-RR

Radio receiving antenna distribution

R-RB

Radio receiving entertainment distribution

R-RE

Radio satellite communication

R-RS

Radio transceiver

R-RQ

Radio transmitter

R-RT

Refrigerator alarm cargo

C-RH

Refrigerator alarm ship stores

C-RA

Resistance temperature indication

C-FT

Rudder angle indicator

C-N

Telephone: Automatic dial

C-J

Telephone: Sound-powered (cargo and ballast control) Telephone: Sound-powered (damage control)

C-6JV C-JZ

Telephone: Sound-powered (electrical engineers)

C-5JV

Telephone: Sound-powered (fueling engineers)

C-3JV

Telephone: Sound-powered (machinery control engineers)

C-2JV

Telephone: Sound-powered (maintenance engineers)

C-4JV

Telephone: Sound-powered (miscellaneous)

C-7JV

Telephone: Sound-powered (ship control and maneuvering)

C-1JV

Telephone: Sound-powered (call)

C-E

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IEEE Std 45.1-2017 IEEE Recommended Practice for Electrical Installations on Shipboard—Design

System

Designation

Television: Closed circuit

R-TC

Television: Monitoring

R-TM

Salinity indicator

C-SB

Security alarm

C-FZ

Sewage tank high-level alarm Shaft revolution indication

C-5TD C-K

Ship service generator local control and indication

K-SG

Smoke indicator

C-SM

Sprinkler alarm

C-FS

Steering control

C-L

Steering gear alarm

C-LA

Tank level alarm

C-TD

Tank level indicator

C-TK

Underwater log

C-Y

Watertight door control

C-WD

Wet and dry bulb temperature indication

C-T

Whistle operator

C-W

Wind direction indicator

C-HD

Wind intensity indicator

C-HE

9.10 Distribution equipment 9.10.1 Distribution panels Distribution panel components, such as enclosing cases, cabinets, latches, locks, and so on, should be constructed of corrosion-resistant materials.

Electrical creepage and clearances should be in accordance with a nationally recognized standard.

All parts of distribution panel interior fittings should be renewable without removing the distribution panel’s insulating base. Circuit breaker elements of unit type construction may be used to build a distribution panel unit.

Each outgoing circuit should have a suitable nameplate. Where there is insufficient space adjacent to the branch circuit breaker for a nameplate, then each circuit should be numbered and a directory list attached to the inside of the door.

Distribution panels for motor, appliance, lighting (including emergency), and other branch circuits should utilize multi-pole circuit breakers or fused switches. These overcurrent protective devices should provide 73 Copyright © 2017 IEEE. All rights reserved.

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IEEE Std 45.1-2017 IEEE Recommended Practice for Electrical Installations on Shipboardâ&#x20AC;&#x201D;Design

overload protection for each ungrounded conductor in each branch circuit. Circuit breakers in grounded neutral distribution panels may include a pole to simultaneously switch the neutral. The number of branch circuits controlled by a single distribution panel should not exceed 18 for three-phase ac branches and 26 for single-phase ac or two-wire dc branches. The wiring space within each enclosure should be of sufficient size to avoid conductor overcrowding and to ensure adequate ventilation. All circuit breakers and fusible switches for motor starting and stopping should have horsepower ratings that meet a nationally recognized standard.

For three-phase distribution panels, buses and primary connections should be arranged such that the phase sequence is A, B, and C. For dc distribution panels, the polarities are positive, neutral, and negative front to back, top to bottom, and left to right, as viewed from the front of the panel. A distribution panel cabinet or enclosing case that is accessible to passengers should be provided with a lock. Dead-front type distribution panels should be used.

Distribution panels should have a degree of enclosure appropriate for the installation location. Watertight distribution panel cabinets should be cast or welded construction with external mounting lugs and externally operable switches. Suitable terminators should be provided for all cables for watertight distribution panels and for cables entering the top of drip proof distributions panels, which may allow condensation or other moisture to drip into the enclosing case or cabinet. Suitable bushings or clamps should be used when cables enter the bottom and sides of drip proof enclosures.

9.10.2 Circuit breakers Circuit breakers should meet other national or international requirements and be tested or certified by a nationally recognized independent testing laboratory as suitable for shipboard applications.

9.10.3 Wire lugs and connectors All lugs should provide adequate contact area and pressure to provide good contact, low voltage drop, lowtemperature rise, and mechanical strength to resist pullout and withstand shipboard vibration.

All pressure type connectors and lugs should conform to UL 486A, or another nationally recognized standard.

If soldering lugs are used, they should have a solder contact length a minimum of 1.5 times the diameter of the conductor.

Tongues should be suitable for the intended application with the contact surface having a suitable finish and adequate area. If the location of soldering lugs is such that any misalignment could result in a shortcircuit or ground fault, then the lug should have two screw holes or otherwise be adequately secured against turning.

If soldering lugs are attached to studs, busbars, etc., which have silver-plated contact areas, the contact area of the lug should also be silver-plated.

9.10.4 Feeder box fittings Feeder box fittings may be of two types. One type of feeder box fitting does not require severing the feeder.

The other type of feeder box fitting utilizes terminal blocks, which are arranged to attach the branch circuit and the two sections of the severed feeder by lugs conforming to the requirements of 9.10.3.

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9.10.5 Branch box fittings Branch box fittings should be provided with bases constructed of flame-retarding and moisture-resistant insulating material. Connections should be provided with spring washers to retain the wires, or connection plates should be provided with upturned lugs or confining walls to retain the wires. Screw holes for securing fittings should not penetrate the enclosure of waterproof boxes.

9.10.6 Connection box fittings Connection box fittings should be provided with insulating bases that are designed for connecting wire lugs or terminals conforming to the requirements of 9.10.3. When providing connections for different voltages in one connection box, the connections for each voltage group should be separated by a barrier and the voltage of each group of terminals should be indicated on the connection box.

9.10.7 Shore connection boxes Shore connection boxes should comply with the following: 

Connection boxes mounted in exposed locations on the weather deck shall have portable cable connection capability utilizing watertight multipole power receptacles or protected terminals.



The terminals should be properly sized and shaped to facilitate satisfactory connections.



There should be phase sequence marking for the terminals for three-phase ac system portable cables.



Terminals should be polarity marked for dc system portable cables.



There should be an instruction plate, or sheet, providing essential information on the ship’s electrical supply system and connection requirements.



Connection boxes should have provisions for bottom entrance of portable cables.

Connection boxes should be designed to prevent moisture or water entrance via the top or sides of the enclosure.

Medium voltage connections to shore should be in accordance with the IEC/ISO/IEEE 80005 series of standards. 

9.10.8 Feeder, branch, and connection boxes 9.10.8.1 General Feeder, branch, and connection boxes should generally be constructed of the following materials: 

Cast brass



Bronze



Malleable iron



Welded iron



Welded sheet steel with corrosive-resistant finish



Pressed sheet brass



Molded composition

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9.10.8.2 Boxes exposed to weather Boxes mounted in locations exposed to the weather should be constructed of the following materials: 

Brass



Bronze



Molded composition



Other suitable corrosion-resistant materials

9.10.8.3 Molded composition boxes Molded composition boxes should be made of flame-retardant material in accordance with ASTM D229-96. The material should also be impervious to oil, moisture, and ultraviolet radiation. The boxes should have mechanical performance characteristics similar to comparable metallic enclosures.

9.10.8.4 Minimum box wall thickness Feeder, branch, and connection boxes should be constructed with minimum box wall thickness as follows: 

For brass and bronze boxes: 2.4 mm



For malleable iron and molded composition boxes: 3.2 mm



For welded iron and welded sheet steel: 1.6 mm



For pressed sheet brass: 1.98 mm

9.10.8.5 Tolerances between box and fittings Metallic boxes should provide an air gap, as follows, between live fittings and the box or cover, unless an insulating barrier is used: 

For 125 V or less: 12.7 mm creepage and 6.35 mm



For 126 V to 600 V inclusive: 6.35 mm air gap

9.10.8.6 Stuffing tube bosses/pads The minimum thickness for stuffing tube bosses or pads should be as follows, excluding wall thickness of the box: 

For molded composition and cast boxes: 6.35 mm



For sheet boxes: 3.17 mm

Where nonmetallic cable hubs or seals are fitted in molded composition boxes, no bosses or pads need be provided.

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IEEE Std 45.1-2017 IEEE Recommended Practice for Electrical Installations on Shipboard—Design

9.10.8.7 Box covers Box covers should have a minimum cover thickness as follows: 

For cast and molded composition boxes: 3.17 mm thick



For all other boxes: 1.6 mm thick

Box covers should be secured with screws of corrosion-resistant material as follows:  For screw cap covers: Screws should have U.S. Standard threads, 12/in or metric equivalent.  For covers other than screw cap covers: Screws should be at a minimum No. 10 gauge, 24 threads/in or metric equivalent.

Covers for watertight boxes should be fitted with gaskets that are thick enough for the application and secured such that a continuous seating and uniform compression of the gasket is ensured.

9.10.8.8 Watertight boxes Watertight boxes should be provided with external mounting feet. No mounting holes should penetrate the enclosure.

9.10.8.9 Box locations Non-watertight feeder, branch, and connection boxes may be used in the following locations: 

Chart room



Navigating bridge



Radio room



Gyro room



Accommodation spaces



Pantries



Passageways adjacent to accommodation spaces



Public washrooms and toilets not equipped with baths or showers

Non-watertight feeder, branch, and connection boxes should not be installed within 3 m of weather deck doors or access openings to the weather where the openings are not protected by an overhead deck that extends the full width of the weather deck to which the doors or openings lead. These boxes may be installed within 3 m of weather deck doors or access openings, if the boxes are concealed in fire-resisting joiner panels. In all other spaces, feeder, branch, and connection boxes should be watertight as required by the location.

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IEEE Std 45.1-2017 IEEE Recommended Practice for Electrical Installations on Shipboard—Design

9.10.9 Receptacles, plugs, and switches—non-watertight 9.10.9.1 General Non-watertight receptacles, plugs, and switches should meet the following standards: 

Should be of rugged construction



Should be capable of withstanding rough treatment and usage

Non-watertight receptacle, plug, and switch enclosures should conform to all applicable requirements of 9.10.8.

Receptacles and switches should have sufficient contact surface and meet all tests and requirements set by a nationally recognized independent testing laboratory.

9.10.9.2 Receptacles All receptacles should meet the following grounding requirements: 

Provide an extra pole or contact grounded to the enclosure

Allow extension of safety circuit or ground connection through supplementary contact in the plug to portable equipment casing The receptacle body supporting current-carrying contacts and terminals should be constructed of flame resisting and moisture-resistant insulating material. There should be a barrier separating current-carrying parts. 

NOTE—Porcelain is not recommended as a barrier for current-carrying components.

All current-carrying components should meet requirements set by a nationally recognized independent testing laboratory.

Receptacles and plugs of different electrical ratings should not be interchangeable, as stated in standards promulgated by a nationally recognized independent testing laboratory.

9.10.9.3 Plugs Plugs should meet the following recommendations based on utilization voltage and load current requirements: 

Conform to all applicable receptacle requirements.



Plug connections should be made in such a manner that no strain is transmitted to terminals and contacts.



Designed such that when in place, they are held in positive contact regardless of vibration level.



All portable equipment plugs should be a type that grips the cord, except for the following equipment:  Desk, table, and floor lamps  Bracket fans used in staterooms and living quarters

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9.10.9.4 Switches Switches should meet the following requirements: 

Be reciprocating or toggle-type switches



Be of the quick make-and-break action type



Have a self-evident position indication

9.10.9.5 Connections Connections for all plugs, receptacles, and switches should be as follows: 

For more than 30 A: Provided with lugs for connecting conductors.



For 30 A or less: Conductors may be held by a binding screw and provided with means for confining the wire.

When receptacles are incorporated as part of a fixture, the receptacle should be a type that has a nationally recognized independent testing laboratory approval, with no restrictions, for the use of any nationally recognized independent testing laboratory approved attachment plug. However, when the receptacle does not have a nationally recognized independent testing laboratory approval rating, then the receptacle should be mounted on a non-conducting surface, or an insulating shield, to effect an insulated area large enough to permit the use of any nationally recognized independent testing laboratory approved attachment plug.

9.10.9.6 Locations Non-watertight receptacles, plugs, and switches may be used in the following locations: 

Chart room



Navigating bridge



Radio room



Gyro room



Accommodation spaces



Pantries



Passageways adjacent to accommodation spaces



Public washrooms and toilets not equipped with baths or showers

Non-watertight receptacles, plugs, and switches should not be installed within 3 m of weather deck doors or access openings to the weather, where the openings are not protected by an overhead deck that extends the full width of the weather deck to which the doors or openings lead, unless the junction boxes for this equipment are concealed in fire-resisting joiner work panels.

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9.10.10 Receptacles, plugs, and switches other than non-watertight 9.10.10.1 General Enclosures for other than non-watertight receptacles, plugs, and switches should be watertight, submersible, or explosion-proof depending on location. The enclosures should conform to all applicable requirements of 9.10.8. Additionally, receptacle enclosures should be designed so that with plugs removed, they can be made to meet the requirements for degree of enclosure.

9.10.10.2 Connections All devices should conform to all applicable requirements of 9.10.9. All receptacles should be a polarized type and designed not to accommodate existing non-grounded plugs. All receptacle plugs should be designed such that, when in place, they are held in positive contact and establish and maintain the required degree of enclosure.

Where threaded caps are used to seal off receptacle openings, they should be mechanically fastened to the cover, or enclosure, by a strong link or hinged strap. Bead chains should not be used for this purpose.

9.10.10.3 Location Watertight receptacles, plugs, and switches should be used in all spaces where non-watertight units are not applicable, except where either explosion-proof or submersible units are required. Watertight units may be used in any location where non-watertight units are permitted. For areas where explosion-proof enclosures are recommended or required, see Clause 27.

Where explosion-proof enclosures are recommended or required, explosion-proof receptacles should have interlocked explosion-proof switches or should be otherwise arranged to avoid an explosion hazard when the plug is inserted or withdrawn. Explosion-proof switches should have poles that are arranged to break all current-carrying legs of the circuit. The installation of switches or receptacles in areas subject to an explosion hazard should be avoided when possible. See Clause 27.

Submersible units may be required in certain applications due to special or unusual locations.

9.10.10.4 Terminal and stuffing tubes Terminal tubes should consist of nonferrous material. Where terminal tubes are installed in contact with dissimilar metals except steel, precautions should be taken to prevent electrolytic action. Terminal tubes should be machined with a standard pipe thread and designed to receive a flanged nut or gland nut. The flange nut and gland nut, when screwed into the tube body, should force a loose collar or gland ring against suitable watertight packing and provide a watertight joint.

Bulkhead tubes should conform to the recommendations listed in this subclause except that the body may be constructed of steel. In addition, the tube body or bulkhead tube should have a nipple of sufficient length to pass through the bulkhead with room for a gasket and lock nut to secure a watertight joint through the bulkhead.

If the nipple is constructed of steel and designed accordingly, it may be welded to the bulkhead to secure the watertight joint.

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Deck-stuffing tubes should be provided with a nut on each side or should be designed specifically for welding to the deck.

9.10.11 Multi-cable penetrators The surrounding frame of a multi-cable penetrator should consist of metal compatible with the metal of the bulkhead, deck, or equipment enclosure to which it is attached. Materials that compose the fitting and seal should not induce electrolysis or cause deterioration of the cable, armor, or cable sheath in any way.

9.10.12 Bolts, taps, and threads All bolts, taps, and threads used in the construction and installation should be U.S. Standard size, metric, or a recognized standard of special thread.

9.10.13 Power factor correction capacitors Power factor correction capacitors may be used in limited shipboard applications to improve a system power factor. This reduces the kilovoltamperes required to supply a given kilowatt load. Power factor correction capacitors may be directly connected to the circuit or connected by means of contactors.

Installation of power factor correction capacitors should not raise the system power factor at the minimum generator load condition above 0.9 lagging. Generator regulator instability may occur at power factors above this level. The installation of power factor correction capacitors causes increased harmonic currents, often requiring increases in cable size, circuit breaker, and contactor rating. In general, cables and circuit breakers should be sized for at least 135% of the rated capacitor load.

Excessive capacitor current will flow when capacitors are connected to solid-state motor controllers, because of silicon control rectifier (SCR) line notching; so power factor correction capacitors should not be installed without isolation transformers. Undesirable ground current will flow if the capacitors are directly connected to ungrounded power systems.

10. Power conversion 10.1 Power electronics Guidance for power electronics based power conversion is provided in IEEE Std 1662 and IEEE Std 1826.

Specific attention should be given to instances where parallel active harmonic filter (AHFs) or active frontend (AFE) drives are applied: it is possible that the switching frequencies may generate harmful harmonics well above the typical 2500 Hz to 3000 Hz range. For this reason, when these devices are present all harmonic calculations and measurements should include consideration of the complete harmonic spectrum up to and including the 100th order.

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10.2 Transformers/reactors 10.2.1 General Dry type transformers should have copper windings, be air cooled by natural circulation, and have a drip proof enclosure as a minimum. Where used for essential services, if applicable, and located in areas where sprinkler heads or spraying devices for fire prevention are fitted, they should be enclosed so that water cannot cause malfunction.

In cases in which capacity, space, or other restrictions warrant, transformers may be of the immersed (nonflammable liquid), self-cooled, or other suitable type. Immersed type transformers should be suitable for operation at 40° inclination without leakage and provided with a liquid level gauge to give indication of the level of liquid. Drip tray(s) or other suitable arrangements should be provided for collecting liquid leakage.

All transformers should be capable of withstanding the thermal and mechanical effects of a short circuit at the terminals of any winding for 2 s without damage. Foil-wound transformers constructed of conductors that are uncoated should be vacuum impregnated. Transformers should comply with IEEE Std 57.12.00, IEEE Std 57.12.90, or IEC 60726, as applicable to the type, size, application, and voltage rating of the units installed.

10.2.2 Installation and location Transformers should be located in dry, well ventilated places, avoiding exposure to the possibility of leaking pipes or condensation. Transformers should be placed so that, insofar as practicable, they are not exposed to mechanical damage. Transformers should be located and mounted to preclude excessive noise in accommodation areas. Suitable lifting lugs or eye bolts should be provided for transformers weighing more than 50 kg.

10.2.3 Type, number, and rating The number and rating of transformers supplying services and systems essential to the safety or propulsion of the ship should have sufficient capacity to ensure the operation of those services and systems even when one transformer is out of service. Transformers should be either the three-phase type or the single-phase type, suitable for connection in a three-phase bank, with a Class B temperature rise. All distribution and control transformers should have isolated primary and secondary windings. Transformers with electrostatic shielding between windings should be used in distribution systems containing nonlinear load devices.

Autotransformers should be used only for reduced voltage motor starting or other suitable special applications.

10.2.4 Voltage regulation The inherent voltage regulation of transformers, at rated output, should be such that the maximum voltage drop to any point in the system in which the transformers are applied does not exceed the system voltage drop values in 9.5.

10.2.5 Parallel operation Transformers for parallel operation should have coupling groups and voltage regulation characteristics that are compatible. The actual current of each transformer operating in parallel should not differ from its 82 Copyright © 2017 IEEE. All rights reserved.

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proportional share of the load by more than 10% of full load current. A means of isolating the secondary connections should be provided.

10.2.6 Temperature rise The limits of temperature rise in a 40 °C ambient should be in accordance with Table 12. Transformers should also be designed to operate in an ambient temperature of 50 °C without exceeding the recommended total hot spot temperature, provided the output kilovoltampere at rated voltage does not exceed 90% of the rated capacity of the transformer with Class A insulation and 94% of the rated capacity of a transformer with Class B insulation.

Table 12 —Transformers and dc balance coils temperature rise Copper temperature rise by resistance (°C)

Hottest spot temperature rise (°C) Class of insulation

Part

A

B

F

H

A

B

F

H

Insulated windings

55

80

115

150

65

110

145

180

NOTE—Metallic parts in contact with or adjacent to insulation should not attain a temperature in excess of that allowed for the hottest spot copper temperature adjacent to that insulation.

Single-phase transformers should permit the use of single conductor cables, without undesirable inductive heating effects, when interconnecting three single-phase transformers in a three-phase bank.

Transformers should be furnished with a permanently attached diagram plate that shows the leads and internal connections and their markings and the voltages obtainable with the various connections.

10.2.7 Terminals and connections Provision should be made to permit the ready connection of external cables to the primary and secondary leads in an enclosed space of adequate size to prevent overheating. Terminals should be readily accessible for inspection and maintenance.

10.2.8 Nameplates The following is the minimum information that should be given on nameplates: 

Serial number or catalog number



Type or form



Number of phases (except single-phase)



Kilovoltampere ratings



No-load voltage rating



Frequency



Temperature rise

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

Percent impedance



Connection type (e.g., delta-delta)

11. Energy storage 11.1 General Energy storage systems are utilized in marine applications primarily for the following reasons: 

Provide continuous power, not interrupted by generator failures and shutdowns



Provide emergency power during generator failures and shutdowns



Serve as buffers between electronics equipment and the power distribution system



Provide dc power to equipment designed for dc input power



Uninterruptible power supplies for navigation, communication, and control systems



Provide standby power for zero emission requirements

Technologies typically used in energy storage systems include rechargeable storage batteries, flywheels, and capacitors.

Additional requirements for energy storage are provided by IEEE Std 1826.

11.2 Specific applications 11.2.1 Controls Electrical control systems are recommended to be powered via an energy storage source because most of these systems are designed “normally energized” (commonly referred to as “failsafe”); this avoids unnecessary equipment shutdown with temporary losses in ac power. Also, continuous power frequently is necessary to eliminate step input functions to controllers, often causing step output functions to process loops.

11.2.2 Instrumentation Many instrumentation circuits utilize dc power for simplicity in reducing the effects of magnetic coupling of continuous and transitory extraneous signals into instrumentation loops. Powering instrumentation via a dc energy storage source isolates instrumentation power from power system transients.

11.2.3 Standby power applications Because the majority of electrical power utilized in marine applications is self-generated and alternative sources of power are not always readily available, many safety systems and other critical loads require standby power.

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It is recommended that ac-powered equipment operated by dc to ac inverters be avoided whenever dcpowered equipment can be utilized directly. The elimination of inverters reduces the number of components subject to failure, thereby improving reliability. Because inverters do not have perfect efficiency, elimination of inverters can reduce the total energy and power requirements.

11.2.4 Buffer applications DC power systems often are installed to serve as buffers between power generators and electronic equipment, reducing the equipment’s exposure to transients and short periods of time when ac power is offfrequency or off voltage. This is a typical uninterruptible power supply (UPS) application.

11.2.5 Bulk energy storage Two applications requiring bulk energy storage may be required depending on the vessel’s specific mission requirements and desired electrical power system architecture.

The first is bulk energy storage sized sufficiently to “ride-through” loss of all ac power generation. The stored energy provides continuity of power to critical ship’s electrical loads for sufficient time to bring on line the standby generator.

The second are loads with unique power requirements, typically a pulse load. Similar to an UPS for small electronic cabinets, the large, dedicated energy storage buffers the pulse load from the power distribution and generation system.

11.3 Rechargeable storage batteries 11.3.1 General Batteries are categorized as either of the following: 

Primary – cannot be easily recharged and discarded after they are discharged



Secondary – can be recharged by passing current through the battery in the opposite direction

Further, secondary batteries can be sub-divided into two broad uses, as follows: 

Used for energy storage and delivering power on demand



Rechargeable batteries used as a primary battery, but recharged after use versus being discarded

Rechargeable storage batteries may be either vented or sealed. When selecting the type of battery, consideration should be given to the suitability of the battery type for the specific application.

Vented batteries are batteries in which the electrolyte can be replaced, which freely release gas during periods of charge and overcharge.

Sealed batteries minimize the quantity of gas released through a pressure relief valve by recombining the products of electrolysis. The electrolyte in this type of battery cannot be replaced.

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Each battery consists of one or more cells with the cells connected in series or parallel, depending on the desired output voltage and capacity. Each cell contains an anode (reducing material or fuel), a cathode or oxidizing agent, and the electrolyte (which provides the necessary internal ionic conductivity).

Some rechargeable batteries may release hydrogen, hydrogen sulfide, or other harmful gases and, therefore, may require adequate fire and ventilation design considerations. See Clause 27 for area classification.

11.3.2 Type of batteries Numerous types of batteries are available. A comparison of batteries by cell type is shown in Table 13.

Table 13 —Comparison of batteries by cell type

Type/Use

Primary SLI (starting, lighting, and ignition) (automotive type Lead Acid)

Projected useful life (years)

Projected cycle lifea (number of cycles)

Wet shelf lifeb (months)

1–3

1

12

0.5–2

50–100

2–3

Specific energy (W-h/kg)

30–40

Commentsc

a) b) c)

Least maintenance Periodic replacement Cannot be recharged

a) b) c)

High hydrogen emission High maintenance Not recommended for float service or deep discharge Low shock tolerance (flat plat design) Susceptible to damage from temperatures >27 °C

d) e) a) b)

Lead Antimony

8–15

600–800

4

30–40

c) d) e) f) a) b) c)

Lead Calcium

<20

<200

6

30–40 d) e) f)

High hydrogen emission (increases with age) More frequent watering and maintenance Periodic equalizing is required for float service and full recharging Low shock tolerance Susceptible to damage from high temperature Can be deep cycled more times than PbCa battery Low hydrogen emission if floated at 2.17 V per cell Low water consumption Periodic equalizing charge is not required for float service if floated at 2.25 V per cell. However, equalizing is required for recharging to full capacity.

When floated below 2.25 V per cell equalizing is required Susceptible to damage from deep discharge and temperatures >27 °C Low shock tolerance Self-discharge ~14%/month

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Type/Use

Lead Selenium

Projected useful life (years)

<20

Projected cycle lifea (number of cycles)

800–1200

Wet shelf lifeb (months)

6

Specific energy (W-h/kg)

Commentsc

a) Low hydrogen emission if floated at 2.17 V per cell b) Periodic equalizing charge is not required for float service if floated at 2.23 V per cell. However, equalizing is required for recharging to full capacity. When floated below 2.23 V per cell equalizing is required c) Susceptible to damage from deep discharge and temperatures >32 °C d) Low shock tolerance (flat plate design) e) Self-discharge ~26%/month

15–30

a) Lead Plante (pure lead)

20+

600–700

4

8–35

b) c) a) b)

Nickel Cadmium (Ni-Cad)

25+

2000+

120+

40–60

c) d) e) f) g)

Nickel Metal Hydride (NiMH)

500 – 2000

75–100

100 – 1200

100–250

Low hydrogen emission if floated at 1.40 V per cell Periodic equalizing charge is not required for float service, but is required for recharging to full capacity High discharge rate (up to 10%/month) High shock tolerance Can be deep cycled Least susceptible to temperature (<43 °C) Can remain discharged without damage

Relatively high self-discharge (up to 4%/day) a)

Lithium Ion (Li-ion, LIB)

Moderate hydrogen emission if floated at 2.17 V per cell Periodic equalizing is required for float service and full recharging Susceptible to damage from temperatures >32 °C

b) c) d) e) f)

Over double energy density compared to Ni-Cad and one-half self-discharge rate High cell voltage ~3.6V Low maintenance No “memory” and no scheduled cycling Requires battery management system to maintain voltage and current within the “safe operating envelope” Self-discharge rate ~1.5% – 2%/month

Cycle life is the number of cycles at which time a recharged battery will retain only 80% of its original ampere-hour capacity. A cycle is defined as the removal of 80% of the rated battery ampere-hour capacity. b Wet shelf life is defined as the time that an initially fully charged battery can be restored at 25 °C until permanent cell damage occurs. c Float voltages listed are for 77 °F. a

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11.3.3 Selection and assembly 11.3.3.1 Battery selection Batteries should be selected to withstand all conditions that may be encountered in the shipboard application.

11.3.3.2 Battery assembly Cells should be assembled in trays or racks of suitable corrosion-resistant material and rigid construction.

Cells should be equipped with handles or lifting points for ease of insertion and removal. The number of cells in a tray or rack will depend on the weight and on the space available for installation. It is recommended that the weight of trays or racks not exceed approximately 110 kg. Battery trays or racks should be arranged so that the trays or racks are accessible and should have a minimum of 250 mm of head room.

Where racks are employed, the floor space underneath the rack plus a sufficient area around the extent of the battery to contain any spillage during maximum vessel inclination shall be curbed and coated with a corrosion-resistant material over the natural floor. Addition of trays beneath the battery rack is not required.

Each cell/battery tray or rack should have a nameplate securely attached to the tray or rack or molded onto the tray case. The nameplate should contain the following: 

Battery manufacturer’s name or trademark



Battery type designation



Ampere hour rating at some specific rate of discharge (rating and rate of discharge should correspond to the specific application of the tray)



Specific gravity of electrolyte when charged (for lead-acid batteries)



Installation date

11.3.4 Battery size categories 11.3.4.1 Large batteries A large battery installation is one connected to a charging device with an output of more than 2 kW computed from the highest possible charging current and the rated voltage of the battery installation.

11.3.4.2 Moderate-sized batteries A moderate-sized battery installation is one connected to a charging device with a power output of 0.2 kW up to and including 2 kW computed from the highest possible charging current and the rated voltage of the battery installation.

11.3.4.3 Small batteries A small battery installation is one connected to a charging device with a power output of less than 0.2 kW computed from the highest possible charging current and the rated voltage of the battery installation.

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11.3.5 Battery installation requirements 11.3.5.1 General Batteries should be located where they are not exposed to excessive heat, extreme cold, spray, steam, or other conditions that would impair performance or accelerate deterioration. Batteries for emergency service, including emergency diesel engine cranking, should be located where they are protected as far as practicable from damage due to collision, fire, or other casualty.

Batteries of different chemistries (e.g., alkaline batteries and lead-acid batteries) should not be installed in the same compartment or enclosure. In addition, on every vessel where batteries of different chemistries are installed, a separate set of necessary maintenance tools and equipment for each battery type should be provided.

Sealed-gelled electrolyte batteries may be installed in locations containing standard marine or industrial electrical equipment if protected from falling objects and mechanical damage, provided all ventilation requirements are met.

Where more than one, normally operating, charging device is installed for any battery or group of batteries in one location, the total power output should be used to determine battery installation requirements. Spare (non-operating) charging devices shall not be counted in the total output requirements.

Each battery conductor, except conductors for engine cranking batteries, should have an overcurrent protective device. Power cables from batteries without overload protection should be secured so as to prevent chafing of the insulation from vibration, shock, or maintenance. Cranking batteries should be located as closely as practicable to the engine or engines served, to limit voltage drop in cables with the high current required. Electric cables, other than those for the battery or battery room lighting, should not be installed in the battery room.

When batteries are installed in a closed space, both mechanical ventilation and emergency sourced lighting are required. Lighting should be provided for battery maintenance with the switch located outside the space in a non-hazardous area. See Clause 27 for details on equipment classification for lighting fixtures installed in battery rooms or lockers.

11.3.5.2 Cables If a cable enters a battery room, the penetration through the bulkhead, deck, or overhead should be made watertight. The cables should be sealed to prevent the entrance of electrolyte by spray or creepage. All connections within the battery room should be resistant to the electrolyte.

The current-carrying capacity of a connecting cable should be at least equal to the maximum charging current or maximum discharge current, whichever is greater. The current carrying capacity of the cables shall be in accordance with IEEE Std 45.8 corrected to the appropriate ambient temperature.

11.3.5.3 Large battery installation Large storage batteries, such as for emergency lighting, emergency post lube oil pumps, switchgear operation and control, and so on, should be installed in a room assigned to the battery only, but they may be installed in a suitable deck locker or box on the open deck if such a room is not available.

A securely attached danger notice should be installed on each door of a battery room, each battery box cover, or each protective covering stating that a naked light or smoking is not allowed in the room.

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Large-sized batteries should not be installed in or ventilated into sleeping quarters.

11.3.5.4 Moderate-sized battery installation Batteries of moderate size, such as those for emergency lighting, engine cranking, communications supply, and so on, should be installed in a battery room, in a box on deck, or in a box or locker (or lockers) in another space such as the emergency generator room, machinery space, storeroom, or other suitable location.

If a moderate-sized installation is in a ventilated compartment such as the engine room and is protected from falling objects, then the batteries do not have to be installed in a box or locker.

Moderate-sized batteries should not be installed in or ventilated into sleeping quarters.

Engine cranking batteries should be located as closely as practicable to the engine or engines served, to limit voltage drop in cables with the high current required.

11.3.5.5 Small battery installation Small batteries, such as those for emergency radio supply, and so on, should be installed in a battery box located as desired in well ventilated spaces.

Small batteries may be installed in an open position if protected from falling objects and mechanical damage. Small battery installations should not be within 2.0 m of radio apparatus or other delicate equipment that would be made inoperative by slight corrosion from battery gases.

Small batteries should not be located in closets, storerooms, or similar spaces.

Small batteries should not be located in sleeping quarters unless hermetically sealed.

11.3.6 Battery arrangement 11.3.6.1 General Batteries should be arranged to permit ready access to each cell or tray of cells from the top and at least one side for inspection, testing, watering (if required), and cleaning. Shelves or racks should not be more than 760 mm deep and 1067 mm high.

For cells that require addition of electrolyte (i.e., wet cells), there should be at least 300 mm, with 380 mm to 460 mm recommended, clear space above the levels of the filling openings.

Trays, when used, should be readily removable for repair or replacement.

When batteries are arranged in two or more tiers, each shelf or rack should have at least 50 mm of space front and back for air circulation.

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11.3.6.2 Battery trays and racks Battery trays and racks should be securely chocked with wood strips or equivalent means to prevent movement. Each battery rack should be secured to prevent movement when subject to the ship motions detailed in 5.11.

Each tray or rack should be fitted with nonabsorbent insulating supports, not less than 20 mm high on the bottom, and with similar spacer blocks at the sides, or with equivalent provision to ensure 20 mm of space around each tray for air circulation.

Each battery tray or rack should be accessible with at least 250 mm of head room.

11.3.6.3 Battery storage lining Each battery room or locker should have a watertight lining for the storage of batteries as follows: a)

Storing batteries on shelves: Install lining to a minimum height of 76 mm with lining thickness and material as follows: 1)

For vented lead-acid type batteries: 1.6 mm minimum lead or other material that is corrosion resistant to the battery electrolyte.

2)

For alkaline type batteries: 0.8 mm minimum steel or other material that is corrosion resistant to the battery electrolyte.

b)

Storing batteries on racks: The battery racks must be made of a material that is corrosion-resistant to the battery electrolyte and have containment space under the rack.

Alternatively, a battery room may be fitted with a watertight lead (steel for alkaline batteries) pan over the entire deck, carried up not less than 150 mm on all sides.

Battery boxes should have a watertight lining to a height of 76 mm with the same thickness requirements as the shelf-lining requirements as given in item a) of this subclause.

Batteries installed in general equipment rooms, electrical rooms, and so on shall meet the same storage requirements as those specified for tray and racks inclusive in 11.3.6.2.

The interior of all battery compartments, including shelves, racks, and other structural parts therein, should be made of corrosion-resistant material or painted with corrosion-resistant paint.

11.3.7 Ventilation 11.3.7.1 General For battery installations using batteries that produce flammable off gas products, all rooms, lockers, and boxes for storage batteries should be arranged and ventilated to avoid accumulation of flammable gas.

Particular attention should be given to the fact that the gas involved is lighter than air, and it will tend to accumulate in any pockets at the top of the space.

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11.3.7.2 Battery rooms All battery rooms should be adequately ventilated. Natural ventilation may be employed where the number of air changes is small and if ducts can be run directly from the top of the room to the open air above, with no part of the cut more than 45º from vertical. If natural ventilation is impracticable, mechanical exhaust ventilation should be provided.

Closed or open loop cooling systems (i.e., air conditioning) may be provided where a sufficient number of air exchanges are provided to eliminate any possibility of gas accumulation.

If mechanical ventilation or cooling system is to be provided, the following recommendations should be adhered to: a)

Battery room ventilation system or cooling system return air should be separate from ventilation systems for other spaces. This will provide once through ventilation/cooling for battery rooms.

b)

Ventilation exhausts shall be at the top of the room and ventilation supplies at the bottom of the room for lead acid battery installations to exhaust the flammable off gas product.

c)

Each blower should have a non-sparking fan.

d)

Fans should be capable of completely changing the air in a maximum of 20 min.

e)

Electric fan motors should be outside the duct and compartment.

f)

When required for large battery rooms, electric fan motors shall be suitable for the area classification in which they are installed.

g)

Electric fan motors should be at least 3 m from the exhaust end of the duct.

h)

The ventilation or cooling system should be interlocked with the battery charger such that the battery cannot be charged without operating the ventilation system.

i)

Interior surfaces of ducts and fans should be painted with corrosion-resistant paint.

j)

Adequate openings for air inlet should be provided near the floor.

11.3.7.3 Battery lockers Battery lockers should be ventilated, if practicable, similarly to battery rooms by a duct led from the top of the locker to the open air or to an exhaust ventilation duct. However, in machinery spaces and similar well ventilated compartments, the duct may terminate not less than 910 mm above the top of the locker.

Louvers, or the equivalent, should be provided near the bottom of the locker for entrance of air.

11.3.7.4 Battery boxes Deck boxes should be provided with a duct from the top of the box to at least 1.2 m above the box ending in a goose neck, mushroom head, or equivalent to prevent the entrance of water. Holes for air entrance should be provided on at least two opposite sides of the box.

The entire deck box, including openings for ventilation, should be sufficiently weather-tight to prevent entrance of spray or run. Boxes for small batteries should have openings near the top to allow the escape of gas.

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11.3.7.5 General equipment rooms, electrical rooms, and other areas Where all the requirements of 11.3.6 are met, the normal ventilation or cooling system in the room where the battery is to be installed may be used.

11.3.7.6 Large battery installation ventilation Large battery installations should be in battery rooms having a power exhaust ventilation system with openings for intake air near the floor. These openings should be of sufficient size and number to allow for the passage of the quantity of air that must be expelled by the ventilation system.

The quantity of expelled air should be at least as follows in Equation (2): (2)

Q = 110 I n

where: Q I n

is the quantity of air expelled in cubic liters per hour is the maximum charging current during gas formation, or 25% of the maximum obtainable charging current of the facility, whichever is greater, in A is the number of cells in series

The ventilation rate for sealed-gelled electrolyte batteries may be reduced to 25% of the ventilation rate for large battery installations.

11.3.7.7 Moderate-sized and small battery installation ventilation Battery rooms or battery lockers for moderate-sized or small battery installations should have louvers near the bottom of the room or locker for the intake of ventilation air.

The ventilation rate for moderate-sized and small battery installations should meet the same requirements as for large battery installations.

11.3.8 Battery rating The capacity of any battery should have minimum output sufficient for its application and duty. In determining battery capacity, consideration should be given to time and rate of discharge.

The capacity of batteries for emergency lighting and power should be as stated in 7.3.3. Where the voltage of the emergency lighting system is the same as the voltage of the general lighting system, battery voltage, at the rated rate of discharge, should be a maximum of 105% of generator voltage when fully charged, and a minimum of 87.5% of generator voltage at the end of rated discharge.

Batteries for diesel engine cranking should have a maximum output sufficient to ensure breakaway torque at the lowest expected temperature. The battery should have a capacity capable of providing a minimum of 1.5 min of cranking at a speed sufficient to ensure engine starting, and have sufficient capacity to provide a minimum of six consecutive engine starts without recharging.

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11.3.9 Charging facilities Charging facilities should be provided for all secondary batteries such that they can be completely charged from a completely discharged state in a reasonable amount of time with regard to the battery service requirements.

Suitable means, such as an ammeter and a voltmeter, should be provided to control and monitor the charging of batteries and to protect them against discharge into the charging circuits.

For floating circuits or other conditions where the load is connected to the battery while the battery is charging, the maximum battery voltage should not exceed a safe value for any connected apparatus. A voltage regulator should be used for any application where safe voltage cannot otherwise be assured. The voltage characteristics of the generator, or generators that will operate in parallel with the battery must be suitable for each application. Where a low voltage battery is floated on a circuit with a resistor in series, all connected apparatuses shall be capable of withstanding line voltage to ground.

When the voltage of the emergency lighting battery is the same as the shipâ&#x20AC;&#x2122;s dc supply, the battery may be arranged for charging in two equal sections with a charging resistor provided for each section. A booster generator may be provided to supply charging voltage as an alternative to charging the battery in two equal sections. With either method, the arrangement of the automatic transfer switch should be such that emergency power is available whether the battery is being charged or not.

Except for batteries that normally stand idle for long periods of time, the charging facilities for any battery should completely charge the battery in a maximum of 8 h without exceeding a safe charging rate. For those batteries that normally stand idle for long periods of time, a trickle charge to neutralize internal losses should be provided where practicable. For low voltage batteries provided in duplicate for communications supply (one in service, the other on charge), the charging rate should be commensurate with the average discharge rate.

11.3.10 Overload protection An overload protective device should be in each battery conductor, except conductors of engine cranking batteries and batteries with a nominal voltage of 6 V or less. For large battery installations, the overcurrent protective device should be located next to, but outside of, the battery room.

Except when a rectifier is used, charging equipment for all batteries with a voltage more than 20% of line voltage should be provided with automatic protection against current reversal.

Fuses may be used for the protection of emergency lighting storage batteries instead of circuit breakers.

11.3.11 Lithium battery application This recommendation is for permanent installation of rechargeable Lithium battery system with charging capacity 15 kW and above.

The Lithium battery technology has proven to meet various application requirements for shipboard applications such as essential UPS service, bulk energy storage, non-essential service with transient duty periodic duty, and continuous duty. The Lithium-ion battery system has favorable characteristics including lightweight, small footprint, higher energy density, higher cell voltage, and long shelf life.

Conversely, Li-ion battery technology has some well-known failure modes that must be understood and addressed if this technology is incorporated in a vessel. If a Li-ion battery is overheated or overcharged, thermal runaway leading to cell rupture could result, which could lead to combustion.

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The key to battery's longevity is the selection of the charging parameters such as current, voltage, and temperature. The accuracy of the applied voltage during the charge plays a significant role in the efficiency and the longevity of the cell. Exceeding the termination voltage leads to over-charging, which, in the short term, increases the available energy from the cell but, in the long run, causes the cell to fail and can lead to safety concerns as mentioned above.

The Lithium-ion battery pack must be procured as a system, which includes the following: 

Battery pack containing individual battery cells arranged for the application



Battery management system (BMS) which prevents operation outside each cell's safe operating area (over-charge, under-charge, safe temperature range) and to balance cells to eliminate state of charge mismatches



Battery charging system

For shipboard application of a Lithium-ion battery system, recommendations are as follows: a)

Protect the battery and battery system from overload and short circuit condition

b)

Provide a continuous battery health monitoring system

c)

Provide independent emergency shutdown system outside the battery room or enclosure as well as at the central monitoring station

d)

Install the battery system in an environmentally controlled space

e)

Provide the battery room with a smoke detection system, fire detection system with audible and visual alarm, and suitable fire extinguishing system The type of the fire extinguishing medium is to be evaluated based on the actual battery chemistry and/or safety assessments.

f)

Calculate battery size with 25% margin

g)

Adhere to additional regulatory body requirements, as applicable

h)

Obtain regulatory approval with specific application certification

i)

Interlock the battery compartment supply and exhaust ventilation with the battery charging system so that charging cannot occur if the fans are not running.

j)

Depending on the batteries’ aggregate capacity/size and/or intended service on board a vessel (for example, non-essential, primary and secondary essential services), the following additional requirements may apply, per applicable regulatory requirements: 1)

HAZID/HAZOP analysis

2)

A detailed risk analysis for evaluating and mitigating potential risks associated with each Lithium battery installation.

NOTE—American Bureau of Shipping (ABS) Guidance Notes on Risk Assessment Applications for the Marine and Offshore Oil and Gas Industries or other equivalent recognized national or international standards define how to conduct the risk analysis.

3)

Unit certification may be required based on application, such as electric propulsion and essential services, or for batteries for which battery charger capacity is greater than 25 kW.

4)

ABS requires an approved structural fire protection requirement for the battery room for each battery installation.

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5)

Lithium batteries may need to be fabricated under an approved quality assurance program, depending on the batteries’ aggregate capacity/size and/or intended service on board a vessel (for example, non-essential, secondary, primary services, etc.).

NOTE—Lithium batteries fall under the United Nations Dangerous Goods Act and Regulations and lithium ion battery packs need to have a clearly marked seal that indicates they have been tested under the UN Manual of Tests and Criteria standards. Moreover, if loose they need to be placed in specific containers to protect them against “grounding” and “overheating.”

12. Electrical power system control 12.1 Supervisory control interfaces Historically, the load-supervisory control system interface has not been defined until late in the design process; often during Product Design. This late definition of the interface has contributed to delays in supervisory control development and compressed testing prior to shipboard delivery. The designer should define this interface for loads prior to Product Design. See Figure 5.

Total Ship or Marine Platform Ship Maneuvering & Control System (MCS) Ship MCS Supervisory Controller

Integrated Electric System Medium Voltage AC, DC or Hybrid Power System Electric System Supervisory Controller

Other Systems Other System Supervisory Controller Bi-directional Control & Data Path

Figure 5 —Supervisory control interfaces

12.2 Control system connectivity Careful consideration should be given to the design of the network for communicating between the load and supervisory control system. In general, the order of preference from high to low for control system connectivity is digital serial communication, discrete digital communication, and analog communication.

Where EMI or survivability is a significant concern, fiber optic connections may be preferable over

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traditional signal and network cables. Designers should also consider wireless and communications over power lines to reduce the need to install dedicated communications cabling.

In general, network bandwidth should be sized to allow 50% growth upon completion of the design.

Redundancy should include, as a minimum, two levels, with no single points of failure. The control design should be such that critical controls cannot be placed into oscillation, or degrade the performance of the control system under any fully or partially loaded condition of the network. Fault tolerance should be such that minor faults do not render the network wholly inoperative. The design should be such that the failure is limited in its impact to the immediate system and, at worst, results in a proportionately degraded system. In addition, when automatic or remote control and monitoring for specific machinery is to operate utilizing such data highways, the following items should be considered: 

The network topology should be configured so that in the event of a failure between nodes or a failure of a node, the integrity of the system as a whole is maintained.



In the event of a failure of the network controller, the network should be arranged to automatically switch to a standby controller. The failure should be alarmed at the associated remote control station.



Safeguards should be implemented to prevent overloading of the network data transmission rates.

Such overloading should be alarmed at the associated remote control station whenever such a condition is approached.

Networks shall incorporate redundancy and should be arranged such that failure of the primary data connectivity automatically causes the alternate connectivity to be switched online. The alternate data connectivity should not be used to reduce the traffic in the primary connectivity.

The control system should be equipped with separate emergency backup data connectivity systems that will allow the continued operation of the vessel in the event of a catastrophic failure of the primary and alternate data connectivity. 

Upon loss of data communications, loads should enter a “fail-safe” mode of operation.

Where possible, the designer should use industry standard network protocols such as TCP/IP or UDP/IP over Ethernet. (e.g., IEEE Std 802.3, IEEE Std 1815).

12.3 Application layer protocol At the application layer, standards directly applicable for implementing electrical power management functions to include QoS and mission priority load shedding do not currently exist. One standard that comes close is the ANSI/EIA 709.1 Control Networking Standard otherwise known as the Lonworks Protocol. At the application layer, the Lonworks Protocol defines a member of a control system in terms of network variables, configuration properties, and manufacturer-defined properties. The Lonworks Protocol includes a large number of standard network variable types (SNVTs) that standardize the application layer for many commercial and industrial control applications. The Lonworks object model does allow for userdefined configuration property types (UCPTs) and a manufacturer-defined section that can be employed to provide the necessary capability to exchange data to implement power management and load shedding algorithms.

To implement electrical power management, the supervisory control should be able to command loads to enter a Load Electrical Power System Mode as well as a Maintenance mode. To implement this, standardized commands at the application layer are needed for the following: a)

Load Electrical Power System Modes 1)

Hard shutdown (unit is off, no communications, power typically turned off with the power distribution system)

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2)

Normal shutdown (unit is off, communications are on, power available at the load)

3)

Standby power mode (unit is drawing the minimum power to respond to commands)

4)

Low power mode (unit is responding to commands in a limited way, restricting the use of power)

5)

Full power mode (unit is fully functional)

b)

Load Maintenance Modes 1)

Tagged out (With the exception of an “emergency stop”, the Electrical Power System Mode cannot be changed until the unit is tagged in.)

2)

Tagged in (Electrical Power System Mode can be changed)

c)

Load Information Interactions 1)

System condition and status

2)

Configuration management data

3)

Maintenance history

4)

Operational log

5)

Condition assessment data

6)

Consumable usage rates and replacement time predictions

7)

Operator and technical manuals

In addition to these modes, the other systems that the load is part of may also have requirements for control interfaces. Therefore, a common engineering control system approach to defining the application layer should be employed as part of a control standardization effort.

In the communication link between the load and the power system, there should be a standardized interface incorporating the ISO model, including the application layer.

12.4 Sources and loads Figure 6 shows typical source and loads in an electrical power system. Sources provide electrical power and loads normally consume electrical power. Some loads may at times regenerate power back to the power system. The electrical power system design, including the control system, should ensure that these regenerative loads do not destabilize the power system. Energy storage can behave either as a source or load depending on its mode.

Loads may simultaneously be part of multiple systems and may therefore communicate with multiple supervisory controllers for different systems. For example, combat systems may be talking to the chillwater system, electric system, etc.

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Protection & Coordination

Protection & Coordination

Status, Information Orders and & Response Direction

Orders and Direction

Status, Information & Response

Control

Control

Load

Load

Source

Power

Power

Power

Simple Load

Controlled Load

Controlled Source

Figure 6 —Sources and loads All sources of power in an integrated electric system shall be controlled in that they shall have both a power interface and a bi-directional control interface to the electrical power system supervisory controller. The operational mode of a controlled source should be established via the control interface. Similarly, commands from the supervisory controller should modify the behavior of the controlled sources to ensure both large signal and small signal stability. Controlled sources should report their condition and operational states via the control interface.

12.5 Voice communication systems Voice systems should provide direct communication between control stations and controlled equipment on a priority link. When the voice communications systems depend on the ship's electrical system, a backup system should be provided that is independent of the electrical system, and that is capable of operating reliably for an indefinite period of time. The voice system should be independent of all other communication systems used for machinery/propulsion control.

13. Motor and motor application 13.1 General application All motors should be compatible with the voltage, phase, and frequency of the supply system. The construction and type of winding should be determined by the conditions under which the motor will operate. Motors may be of the wound-rotor induction, squirrel-cage induction, synchronous, or suitable commutator type. Motors should be constructed so that their operation is not impaired by vibration and shock likely to arise under normal service conditions. Windings and current-carrying parts should be copper, and fasteners securing the current-carrying parts should be provided with means to prevent loosening caused by vibration. Motors used with adjustable speed drives (ASDs) should be capable of 99 Copyright © 2017 IEEE. All rights reserved.

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operating successfully on the non-sinusoidal input power from the drive. Squirrel-cage induction motors should be used wherever suitable.

Where water-cooling is used, the cooler should be arranged to prevent water entry into the machine from heat exchanger leakage or condensation.

Motors in damp spaces or in the weather, especially motors left idle for appreciable periods, should be provided with an effective means (e.g., internal heaters) to prevent the accumulation of condensation.

Measures should be taken, where necessary, to prevent the circulation of current between the shaft and the bearings, especially when ASDs are being utilized.

In the interest of achieving a favorable power factor, motors should be selected that closely meet the actual load requirements. Oversize motors should be avoided.

Care should be taken to locate drip proof motors to avoid bilge water. In general, motors should not be located below the level of the floor plates unless they are watertight. However, where located in openings in the floor plates where they are not subjected to splashing bilge water and are readily visible and serviceable, drip proof motors may be used.

13.2 AC and DC motors—general Electric motors are selected for the load requirements and the voltage, phase, and frequency of the power system. The motor design and construction should be suitable for both the load application and environmental conditions. For most applications, three-phase squirrel cage induction motors are recommended. All motors should be designed and constructed to meet NEMA or IEC dimensional and performance standards. For squirrel cage induction motors 7.5 kW (10 hp) to 373 kW (500 hp), it is recommended that motors comply with IEEE Std 841. For motors larger than 373 kW (500 hp), it is recommended that motors comply with API Std 541.

Variable-speed ac motors, in addition to the requirements of this subclause, should be carefully matched to the drive motor controller for optimum performance.

13.3 Selection 13.3.1 Three-phase motor voltages The normally recommended voltage for ac three-phase integral horsepower motors operated on 480 V systems is 460 V. Motors rated for 200, 230, 380, 400, 575, and 660 V are recommended for supply systems voltages of 208, 240, 400, 420, 600, or 690 V, respectively. Where motors larger than 150 kW (200 hp) are used, 2300, 3300, 4000, or 6000 V motors are usually preferable. In view of the problems of classified locations and severe environmental conditions, special consideration should be given to all aspects of the installation before using motors and related controllers of voltages above 690 V. 13.3.2 Single-phase ac motor voltages Single-phase motors, normally limited to fractional horsepower loads, usually are rated at 115, 200, 220, and 208/230 V when driving fixed equipment. For portable motors, 115 V or 220 V are preferred.

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13.3.3 Supply voltage The supply voltage and frequency should be as near the nameplate rating as practical and should not deviate more than 10% in voltage and 5% in frequency, above or below rating. The sum of voltage and frequency deviations may total 10%, provided the frequency deviation does not exceed 5%.

13.4 Installation and location Motors exposed to the weather or located where they would be exposed to seas, splashing, or other severe moisture conditions should be watertight or protected by watertight enclosures. Such enclosures should be designed to prevent internal temperatures in excess of motor ratings. Motors should be located so they cannot be damaged by bilge water. Where such a location is unavoidable, they should be either submersible or provided with a watertight coaming to form a well around the base of the equipment and a means for removing water. A suitable NEMA or IEC enclosure should be used as required by the authority having jurisdiction. Fan-cooled motors should not be installed in locations subject to ice formation.

For motors in hazardous locations, see Clause 27.

Horizontal motors should be installed, as far as practicable, with the rotor or armature shafts in the fore and aft direction of the vessel. If motors must be mounted in a vertical or an athwartship position, the motors should have bearings appropriate for the intended installation.

Motors (except for submersible motors, sealed motors, or motors for hazardous locations) should be designed to permit ready removal of the rotor, stator components, and bearings, and to facilitate bearing maintenance. All wound-rotor ac motors, synchronous motors, and commutating motors of the enclosed type, except fractional horsepower motors, should have viewing ports or readily removable covers at the slip ring or commutator end for inspection of the rings, commutator, and brushes while in operation.

Eyebolts or equivalent should be provided for lifting motors.

13.5 Insulation of windings Insulating materials and insulated windings should be resistant to moisture, sea air, and oil vapor. All formwound coils for ac motors and assembled armatures, and the armature coil for open-slot dc construction, should utilize vacuum pressure impregnated solventless epoxy insulating systems.

For ac motors, all random-wound stators and rotors having insulated windings should utilize vacuum pressure impregnated solventless epoxy Class F or H insulation systems, with Class B rise, or be of the encapsulated type.

Most standard NEMA frame motors are fabricated using non-hygroscopic NEMA Class F or H insulation.

In totally enclosed motors, the normal insulation can be expected to provide satisfactory service. If open drip proof or weather-protected motors are selected, it is recommended that the insulation be a sealed system. Motors with NEMA Class F insulation and with a NEMA Class B rise at rated motor horsepower are available in most motor sizes and types and are recommended to provide an increased service factor and longer insulation life.

All field coils for dc motors should be treated with varnish or other insulating compound while being wound, or should be impregnated. The finished winding should be water- and oil-resistant.

Abnormal brush wear and commutator maintenance may occur in motors containing silicon materials.

Silicon materials should not be used in motors with brushes.

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13.6 Locked rotor kVA Three-phase induction motors normally are designed for a starting kVA of five to six times the horsepower rating. This starting kVA corresponds to NEMA locked rotor Codes F and G and is suitable for most applications. IEC motors exhibit related characteristics, but not 100% equivalent. It may be desirable that large motors be specified with lower inrush currents to minimize the effects of starting on the power source. Consult the motor manufacturer for specific details.

13.7 Efficiency It is recommended that designers of new installations consider the use of energy-efficient motors. For a given horsepower rating and speed, the efficiency of a motor is primarily a function of load. The full load efficiency generally increases as the rated horsepower or speed increase.

Efficiency increases with a decrease in slip (difference between synchronous speed and full load speed of an induction motor, divided by the synchronous speed). High slip motors usually yield higher overall efficiency for applications involving pulsating, high inertia loads.

Reference ANSI/NEMA MG 1-1998 or IEC 60034 for additional guidance. Generally, the inrush current on energy-efficient motors is higher than that for standard motors.

13.8 Lubrication See 5.11, for ship motion requirements for motor lubrication systems.

Means should be provided to prevent lubricant from creeping along the shaft or otherwise contacting the insulation or any live part. Each oil-lubricated bearing should be provided with an overflow. Where ring lubrication is employed, the rings should be constrained so that they cannot leave the shaft. Each selflubricated sleeve bearing on a machine 100 kVA ac/100 kW dc or greater should be fitted with an oil gauge or an inspection cover for visual indication of oil level.

13.9 Terminal arrangements All motors should be provided with terminal boxes appropriate to their type of enclosure. Terminal boxes should be of sufficient size to accommodate wiring without crowding, and each box should be of adequate mechanical strength and rigidity to protect the contents and to prevent distortion under all normal conditions of service.

Cables of different voltage classes shall not be terminated in the same terminal box. Wiring for instrumentation, sensors, and safety devices should be installed in separate terminal boxes.

Motors should have the terminal leads suitably secured to the motor frame. The end of these leads should be fitted with approved connectors suitable for use with terminal lugs on incoming cables. All connections to the interior of motors as well as those to the power supply should be provided with efficient locking devices.

The leads of watertight motors should be brought into watertight junction boxes through watertight seals.

The leads of explosion proof motors should be terminated to maintain the explosion proof integrity of the motor.

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Special consideration should be given to terminal enclosures of multispeed ac motors to ensure adequate space for connecting and insulating multiple cables.

13.10 Corrosion-resistance parts All motor screens, interior bolts, nuts, pins, screws, terminals, brush holder studs, springs, hand hole cover bolts, nuts, and such other small parts that would be seriously damaged and rendered ineffective by corrosion should be corrosion-resistant. Steel springs should be treated to resist moisture in such a manner as not to impair their spring quality.

Motors should be painted with a corrosion-resistant finish or otherwise protected against corrosion.

13.11 Nameplates All motors should be fitted with nameplates of corrosion-resistant material. Motor nameplates should be in accordance with the appropriate standard of construction for the motor.

13.12 Ambient temperature Motors for main and auxiliary machinery spaces containing significant heat sources such as prime movers and boilers, except machine tools, should be selected on the basis of a 50 °C ambient temperature or the actual expected maximum. Motors for machine tools may be selected on the basis of 40 °C ambient temperature. Motors in locations where the ambient temperature will not exceed 40 °C may be selected on the basis of 40 °C ambient temperature.

Motors that must be installed where the temperature normally will exceed 50 °C should be considered as special and should be designed for 65 °C or the actual expected ambient temperature. Consideration should be given to ensuring satisfactory lubrication at high temperatures.

If a machine is to be utilized in a space in which the machine’s rated ambient temperature is below the assumed ambient temperature of the space, it should be used at a derated load. The assumed ambient temperature of the space plus the machine’s actual temperature rise at its derated load should not exceed the machine’s total rated temperature (machine’s rated ambient temperature plus its rated temperature rise).

13.13 Limits of temperature rise It is recommended that ac and dc motors have a design temperature rise of 80 °C, by resistance, in a 40 °C ambient temperature (NEMA Class B), but be constructed with a minimum of NEMA Class F insulation to provide optimum balance between initial cost and long-life operations. See 5.11 for the applicable ambient temperature requirements.

Motors are normally designed for 40 °C ambient temperatures, and thus, they should be derated in accordance with manufacturer’s recommendations if operated in higher ambient temperatures. Insulation of motor windings with quality insulation materials that are designed to be resistant to the salt laden moist atmosphere locations is recommended.

Deck-winch and direct-acting capstan motors should be rated on a full load run of at least 1/2 h; directacting windlass motors should be rated on a full load run of at least 1/2 h; and those operating through

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hydraulic transmission should be rated for 30-min idle pump operation, followed by full load for 1/4 h.

Steering-gear control motors should be rated on a full load run of 1 h.

The temperature rise of each of the various parts of ac motors and dc motors when tested in accordance with the full load rating should not exceed values given in Table 14.

Table 14 —Limits of observable temperature rise for ac motors Item

1

Machine part Windings a. All except b. and c. b. Totally enclosed non ventilated enclosures only c. Excapsulated only d. 1500 hp and less e. Over 1500 hp

2

Field winding of synchronous motors a. Salient pole b. Totally enclosed

Method of temperature determination

A

Ambient

50 °C B F

H

A

65 °C B F

H

Resistance Resistance

50 55

70 75

95 100

115 125

34 40

60 65

80 85

105 110

Resistance Embedded detector Embedded detector

55 60

75 80

100 105

130

40 40

65 65

85 90

115

55

75

100

125

40

65

85

110

Resistance Resistance

50

70 75

95 95

115 115

35

60 65

80 85

105 105

Where provision is made for ensuring an ambient temperature being maintained at 40 °C or less, as by air cooling or by location outside of the boiler and engine rooms, the temperature rises of the windings may be 10 °C higher.

13.14 Motor application 13.14.1 General Motors should be selected for the particular application. Motors should be rated for continuous duty unless used in an application that specifically imposes an intermittent or varying duty.

Generally, motors should be of the drip proof and guarded type, unless an equipment enclosure provides an equivalent (or greater) degree of ingress protection. Motors subjected to excessive dripping of water or oil should be totally enclosed or watertight. Motors on the open deck should be watertight unless enclosed in watertight housings.

Because machinery space air can contain oil vapor, consideration should be given to using totally enclosed or totally-enclosed fan-cooled motors, or to piping the ventilating air to enclosed self-ventilated motors to prevent oil accumulation on the windings.

13.14.2 AC motors Because most applications do not require speed control of the driven load, single-speed squirrel-cage induction motors should be used whenever possible. If speed control is required, consideration should be given to solid-state ASD controllers or multispeed squirrel-cage induction motors. The windings may be 104 Copyright © 2017 IEEE. All rights reserved.

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grouped for series or parallel operation to provide a two-to-one ratio of speeds, or two or more independent windings may be used to provide other ratios of synchronous speeds. A wound-rotor induction motor may also be used with suitable control equipment.

13.14.3 DC motors For applications requiring speed variation, shunt- or compound-wound dc motors should be used.

Applications requiring only small adjustments should utilize shunt field control, which will readily accommodate a speed change of 10% with a corresponding change in output torque. For applications where greater speed variation is required, a combination of armature voltage and/or shunt field control should be utilized.

13.14.4 Ventilating fan and blower motors Ventilating fans and blowers may be driven by either ac or dc motors. For dc applications where the motor speed exceeds 600 rpm, compound-wound motors are recommended. In other instances, a shunt-wound motor should be used.

Any motor that drives an axial flow fan and draws air from, or discharges to, the open deck should be waterproof.

13.14.5 Pump motors Motors for operating close-coupled pumps should be totally enclosed. Alternatively, motors may be drip proof, with the driving end totally enclosed or designed to prevent liquid from entering the motor.

13.14.6 Refrigerated spaces In general, motors should not be installed in refrigerated spaces. If installed, such as for recirculating fans, special consideration should be given to the effects of condensation.

13.14.7 Galley, laundry, workshop, print shop, and similar spaces Motors for installation in these spaces should be totally enclosed or totally enclosed fan-cooled. Where the enclosing case of the appliance provides equivalent protection, open or drip proof motors may be used.

13.14.8 Applications in hazardous locations See Clause 27 for additional recommendations.

13.14.9 Deck machinery motors Motors should be waterproof unless located in deckhouses, below deck, or otherwise suitably protected.

The following apply to ac and dc motors located in these spaces.

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13.14.9.1.1 AC motors Single or multispeed constant-torque squirrel-cage motors generally provide sufficient speed points for a windlass, winch, or capstan drive. ASD controllers or wound-rotor motors with several types of impedance control may be used if additional speed control is required.

13.14.9.1.2 DC motors Motors may be stabilized shunt, compound, or series wound. With a warping head, a stabilized shunt or compound-wound motor should be used. Speed control with special operating characteristics is usually required.

13.15 Duty rating The duty rating required depends on the mechanical configuration of the drive. For indirect drives, such as dc-adjustable voltage drives or electrohydraulic drives, consideration should be given to the fact that the motor driving the motor-generator set or pump will be operating continuously at light load with superimposed intermittent loading.

The minimum duty ratings recommended for windlass, capstan, and winches are as in Table 15.

Table 15 —Minimum duty rating for windlass, capstan, and winches

a

Windless

Capstan

Cargo winch

Topping and vang winch

Direct gear

30 min

30 min

30 min

15 min

Direct gear with warping head

30 min viaa

30 min viaa

30 min viaa

—

Indirect (motor driving MG set or pump)

30 min viaa

30 min viaa

30 min viaa

—

Varying duty comprises at light load followed by full load for the specific time period. Boat winches and watertight door operators should have a minimum duty rating of full load for 5 min.

13.16 Steering gear motors 13.16.1 AC motors For direct-drive steering gears, a wound-rotor motor with a breakdown torque of at least twice the full load torque or a continuously rated squirrel-cage motor with reversible ASD is recommended.

For an indirect-drive steering gear with a dc-adjustable voltage drive or an electrohydraulic drive, the squirrel-cage motor should be rated for continuous operation at 15% of rated load, followed by full load for 60 min.

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13.16.2 DC motors For direct-drive steering gears, a compound-wound motor with a 60-min intermittent duty is recommended.

For an indirect-drive steering gear, the motor driving the motor-generator set or pump should be shunt or stabilized shunt wound and have the same 60-min varying duty rating as the ac motor as given in 13.16.1.

13.17 Motor brakes 13.17.1 Types Brakes may be of the shoe, band, or disk type, and they may be mounted separately or attached to the motor.

13.17.2 AC brakes All ac brakes should be wound for the motor supply voltage and frequency.

13.17.3 DC brakes All dc brakes should be insulated for the same voltage as that of the motors for which they are used. The brake winding may be series or shunt type as desired. Series-wound brakes should be designed to release down to at least 40% full load current and in every case on the starting current, and to set at not more than 10% full load current. Shunt-wound brakes should operate satisfactorily at 80% rated voltage at maximum working temperature, and the construction or protection should be such that the windings will not be damaged by inductive discharge. Shunt coils may have an external series and discharge resistance.

13.17.4 Accessibility Shoe-type brakes should permit the removal of the brake shoes and brake wheel without the removal of the magnet, magnet housing, brake base, or without disturbing the base alignment of the brake. Disk-type brakes should permit the removal of the brake housing away from the motor or the motor away from the brake housing. The construction of the brake should be such that exact alignment of the shoe or disk with the centerline of the armature is not necessary.

13.17.5 Enclosures 13.17.5.1 General The electric operating portion and the mechanical portion (wheel, shoes, etc.) of the brake may be open, drip proof, or waterproof as required for the application.

13.17.5.2 Open type A shield should be provided over the mechanical portion for safety and protection. Brake coil housings should be drip proof or watertight. Brake coil housings of the waterproof type, if provided with drain plugs, should carry a caution plate advising: 107 Copyright Š 2017 IEEE. All rights reserved.

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CAUTION Do not drain when hot.

The waterproof housing should be arranged for drilling and tapping to suit kick pipe or stuffing tubes.

13.17.5.3 Drip proof enclosed A drip proof enclosure covering the entire brake should be provided.

13.17.5.4 Waterproof enclosed A substantial waterproof housing should be provided to enclose all parts of the brake. Shaft seals should be included.

13.17.6 Construction All bolts, nuts, pins, screws, terminals, springs, and so on should be of corrosion-resistant material or steel suitably protected against corrosion. Steel springs should be treated to resist moisture in such a manner as not to impair their spring quality.

All bolts, nuts, pins, screws, terminals, springs, and so on should be of corrosion-resistant material or steel suitably protected against corrosion. Steel springs should be treated to resist moisture in such a manner as not to impair the spring quality.

13.17.7 Nameplate A nameplate providing the following data should be mounted conspicuously on the brake: 

Marine (name of apparatus)



Name of manufacturer



Type



Frame



Voltage



Armature travel



Torque



Spring compression



Rating (time)



Serial number



Coil specification number



Inrush current (ac only)



Frequency (ac only)



Number of phases (ac only)

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

Maximum continuous current (dc only)



Series or shunt (dc only)

13.17.8 Brake application Brake coils for intermittent rated motors should not overheat when energized for the time rating of the motor to which they are connected. Continuously rated coils should be capable of operation continuously at rated voltage and current.

Brakes should have a torque rating equivalent to the torque rating of the motors to which they are attached.

Brake magnets should not be noisy when the armature is seated against the core. DC brakes may be used with power supplied from ac/dc rectifiers.

13.18 Magnetic friction clutches 13.18.1 General Magnetic friction clutches should be insulated for the same voltage as that of the motors or other electric equipment with which they will be used. Magnetic clutches consist of two sections, one containing the magnetic winding and the other a steel disk or faceplate that forms the armature of the magnet. When current is passed through the winding, the clutch becomes engaged; when the circuit is opened, the clutch becomes disengaged. The disengagement should be assisted by a spring plate or springs, and when disengaged, the two sections should stand a short distance apart with a positive running clearance. The usual type of clutch provides direct magnet action, the magnet being located so that its direct pull produces the pressure between the friction surfaces on the magnet and armature. The engagement of the clutch members, when the coil is energized, should be smooth and positive. The clutch should have the pressure between the members balanced within the clutch so that there is no end thrust. Magnetic clutches should be accurately balanced at operating speeds.

The friction lining and magnet coil should be readily accessible without disturbing either the driving or the driven shaft. Suitable means for adjustment of the friction surface should be provided.

All small parts should be protected against corrosion as recommended for motors. Collector rings for current supply to the clutch should be of non-corroding material. Double-brush contacts should preferably be supplied to ensure positive contact at all times.

13.18.2 Nameplate A nameplate should be provided giving the following data: 

Marine (name of apparatus)



Name of manufacturer



Type



Voltage



Maximum continuous current



Torque 109 Copyright © 2017 IEEE. All rights reserved.

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

Serial number



Normal revolutions per minute

14. Adjustable speed drive (ASD) applications Recent successes in power electronics made it economical and energy efficient to apply ASDs to start, accelerate, and control the speed of any motor-driven load on ships and mobile platforms from small pumps to multi-megawatt electrical propulsion systems. In the majority of applications, lighter and reliable ac motors are advantageous compared to dc motors.

The system or sub-system designer will determine when an ASD/motor combination is appropriate in consultation with the customer. The system or sub-system designer should work with the ASD supplier to define the requirements for matching the motor and ASD to the load, including input transformer if required, to the power system such that they operate as a system with no unsatisfactory transient, torsional, heating, or power-quality problems. The ASD/motor/load system shall be suitable for the ship’s service conditions, including the ambient temperature and humidity conditions; input power-supply voltage and minimum and maximum short-circuit capacities of the source; and auxiliary power-supply voltage.

It is recommended the ASD and all related parts should be suitable for a minimum of five years of operating life. The vendor shall identify any redundancy requirements necessary to meet this end. The vendor shall provide an expected mean time between failures (MTBF) and mean time to repair (MTTR) for the ASD under the listed service conditions. The vendor shall list all components that are expected to require replacement in a 20-year operating life.

It is recommended the ASD system and all its components shall be designed and manufactured for a minimum 20 year service life. When evaluating the VSD, consideration should be given to availability of spare parts and appropriately trained field service personnel. Required maintenance and frequency to achieve this service life should be clearly documented.

Solid-state electronic power conversion equipment introduces electrical noise due to the frequency conversion process. Therefore, noise mitigating equipment such as power filters (passive band filters, active filters, ASDs fitted with AFEs, di/dt filters, braking resistors, and properly shielded cables) are vital to each system. This equipment must be identified as vital components for each and every vital system.

This equipment may also be used in a non-vital system; however, the nature of their operation may influence the entire power system. While failure mode and effects analysis (FMEA) deals with vital system and vital components, these devices may influence and must be treated as such. All requirements such as redundancy for single point failure must be analyzed for those components. Individual component health should be monitored and appropriate protective features be added to the control system so that the safety of the system can be properly maintained with no adverse effect to the other system.

ASD applications for ships and mobile oil platforms should comply with IEEE Std 1566 and IEEE Std 1662.

15. Electric propulsion and maneuvering system 15.1 Scope This clause provides recommendations covering general specifications, testing, installation, operation, and maintenance of electric propulsion systems. Although these recommendations relate specifically to the 110 Copyright © 2017 IEEE. All rights reserved.

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electric propulsion equipment, they also address mechanical equipment where required for the successful functioning of the entire system.

The application of power electronics technology to large motor drive systems has resulted in the successful installation of shipboard electric propulsion systems that derive input power from a central, fixed-frequency or dc power generation plant that also provides power to the ship service loads. These integrated electric power systems require careful consideration of the physical location requirements of system equipment, cable protection, and control devices as well as special attention to power distribution and load management to ensure an uninterrupted supply of power to vital systems.

There are currently a variety of electric propulsion concepts, such as, but not limited to, fixed speed controllable pitch propeller and variable speed with fixed or controllable pitch propeller. Variable speed systems are usually supplied from static power converters, such as dc/dc drives, dc drives with thyristor converters, ac drives with pulse width modulated (PWM) converters, load commutated inverters (LCIs), and cycloconverters. Each type may require unique considerations to network and mechanical design of the system.

15.2 Regulations Classification societies and regulatory agencies generally provide detailed rules and regulations for structural foundations, strength of materials, installation, inspection, tests, plans, and data. These regulations should be consulted in the design and installation of electric propulsion systems and equipment.

15.3 System requirements 15.3.1 General The design of an integrated electric power system should consider the power required to support ship service loads and propulsion loads under a variety of operating conditions, with optimum usage of the installed and running generator sets.

In order to prevent excessive torsional stresses and vibrations, careful consideration should be given to coordination of the mass constants, elasticity constants, and electrical characteristics of the system. The entire system includes prime movers, generators, converters, exciters, motors, foundations, slip-couplings, gearing, shafting, and propellers.

The normal torque available from the propulsion motors for maneuvering should be adequate to permit the vessel to be stopped or reversed, when the vessel is traveling at its maximum service speed, in a time that is based on the estimated torque-speed characteristics of the propeller during maneuvering and on other necessary ship design characteristics, as determined from hull model testing and computation. Adequate torque margin should also be provided in ac propulsion systems to guard against the motor pulling out of synchronism during rough weather and on a multiple screw vessel, when turning. This margin should be based on information related to propeller and ship characteristics, as well as the propulsion driveâ&#x20AC;&#x2122;s characteristics.

There are offshore support vessels with critical operational requirements of using electric propulsion system and thrusters supported by a dynamic positioning system. The applicable class and regulatory requirements for dynamic positioning regarding power system and thrust devices should then apply for the propulsion system, in addition to the requirements in this clause.

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Systems having two or more propulsion generators, two or more propulsion drives, or two or more motors on one propeller shaft should be so arranged that any unit may be taken out of service and disconnected electrically, without affecting the other unit.

15.3.2 Power quality and harmonic distortion The power quality recommendations for ship service systems, as specified in Clause 1, for voltage and frequency, should be used also in integrated electrical propulsion plants, with the following exceptions:  A dedicated propulsion bus should normally have a voltage total harmonic distortion (VTHD) of no more than 8%.  A nondedicated main generation/distribution bus should not exceed a VTHD of 8%, and no single voltage harmonic should exceed 5%.  A harmonic distortion calculation and measurements should be carried out, in accordance with a method equivalent to IEEE Std 519. Normally, it will be desired to perform an initial calculation as input to the final design of electrical equipment, such as generators and transformers, and a final calculation after the equipment is designed using the final design parameters. Measurement of harmonic distortion to verify analytic results, should be done in a variety of typical operating conditions and voltage levels to establish a baseline for the system. 

For parallel active filters or active PWM front-end type VSDs (PWM type), related harmonics often exceed the 49th order. Therefore, when this type of VSD is used, calculations and measurements should take into consideration harmonics up to the 100th order, which is beyond the requirements of IEEE Std 519.

In order to achieve the THD limits, consideration should be given to using equipment such as transformers, passive or active filters, or rotating converters.

When passive harmonic filters or capacitors are used for nonlinear current compensation, attention should be paid to any adverse effect of fluctuations on the RMS and peak values of system voltage.

Interruption of circuit protection (fuse or circuit breaker) in parallel connected harmonic filter circuits should be detected. Capacitors and reactors in harmonic filter circuits should be equipped with health monitoring and alarm circuits. This should apply also to the LCL type filters that are common in AHFs and AFE VSDs. For vital system applications, VSD associated filters should be included in the FMEA. Harmonic distortion calculations and measurements should normally be carried out, in accordance with commonly accepted standards such as a method equivalent to IEEE Std 519 or an appropriate marine certifying harmonic standard, such as ABS, DNV, etc. Normally, it will be desired to perform an initial calculation as input to the final design of electrical equipment, such as generators and transformers, and a final calculation after the equipment is designed using the final design parameters. Measurement of harmonic distortion, if desired to verify analytic results, should be done in a variety of typical operating conditions and voltage levels to establish a baseline for the system. Consideration should be given to the fact that the effectiveness of harmonic mitigation equipment can be negatively influenced by power system conditions such as voltage imbalance and background voltage distortion. This is particularly true for transformer phase shifting strategies such as 12, 18, or 24 pulse systems. When parallel active filters or AFE VSDs are used for nonlinear compensation, special attention must be given to the higher frequency harmonic distortions that these methods introduce, Therefore, harmonics up to the 100th must be considered in both calculations and measurements.

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15.3.3 Redundancy Redundancy should be provided within the propulsion system in accordance with requirements of the authority having jurisdiction to ensure safe operation of the vessel.

15.3.4 Safety For systems in which excessive overspeeding of the propulsion motors may occur, such as under light load conditions or upon loss of a propeller, suitable overspeed protection should be provided. Provision should be made for protection against severe overloads, excess currents, and electrical faults that could result in damage to the plant. The protective equipment should be capable of being set so that it will not operate on overloads or excess currents likely to be experienced in a heavy seaway or when maneuvering.

The main propulsion circuit should be provided with ground leakage indicating devices that will operate when the insulation resistance is 100 kΊ or less. Excitation circuits of propulsion motors should be provided with lamps, meters, or other suitable means to indicate continuously the state of the insulation of the excitation circuits under running conditions.

15.4 Prime movers for integrated power and propulsion plants Prime movers, such as diesel engines, gas turbines, or steam turbines, for the generators in integrated electric power systems shall be capable of starting under dead ship conditions in accordance with requirements of the authority having jurisdiction. Where the speed control of the propeller requires speed variation of the prime mover, the governor should be provided with means for local manual control as well as for remote control.

The prime mover rated power, in conjunction with its overload and the large block load acceptance capabilities, should be adequate to supply the power needed during transitional changes in operating conditions of the electrical equipment due to maneuvering, sea, and weather conditions. Special attention should be paid to the correct application of diesel engines equipped with exhaust gas-driven turbochargers to ensure that sudden load application does not result in a momentary speed reduction in excess of limits specified in Table 7.

When maneuvering from full propeller speed ahead to full propeller speed astern with the ship making full way ahead, the prime mover should be capable of absorbing a proportion of the regenerated power without tripping from overspeed when the propulsion converter is of a regenerative type. Determination of the regenerated power capability of the prime mover should be coordinated with the propulsion drive system.

The setting of the overspeed trip device should automatically shut down the unit when the speed exceeds the designed maximum service speed by more than 15%. The amount of the regenerated power to be absorbed should be agreed to by the electrical and mechanical machinery manufacturers to prevent overspeeding.

Electronic governors controlling the speed of a propulsion unit should have a backup mechanical fly-ball governor actuator. The mechanical governor should automatically assume control of the engine in the event of electronic governor failure. Alternatively, consideration would be given to a system, in which the electronic governors would have two power supplies, one of which should be a battery. Upon failure of the normal supply, the governor should be automatically transferred to the alternative battery power supply. An audible and visual alarm should be provided in the main machinery control area to indicate that the governor has transferred to the battery supply. The alternative battery supply should be arranged for trickle charge to ensure that the battery is always in a fully charged state. An audible and visual alarm should be provided to indicate the loss of power to the trickle charging circuit. Each governor should be protected separately so that a failure in one governor will not cause failure in other governors. The normal electronic 113 Copyright Š 2017 IEEE. All rights reserved.

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governor power supply should be derived from the generator output power or the excitation permanent magnet alternator. The prime mover should also have a separate overspeed device to prevent runaway upon governor failure.

15.5 Generators for integrated power and propulsion plants 15.5.1 General Generator construction should be in accordance with 8.4.

The power rating of generators in an integrated electric plant is not limited to the recommendations in 8.4.

The generator should be rated for the total distortion of currents in the electrical system.

If the insulation is not comprised of self-extinguishing material, provisions for a fire extinguishing system suitable for fires in electrical equipment should be provided for the generator, which is enclosed or in which the air gap is not directly exposed.

The generators should be constructed so that they withstand, without mechanical damage, an overspeed of 25%. The generators should be able to operate in parallel and share load proportionately.

Means should be provided to prevent circulating currents passing between the journal and the bearings.

The generators of an integrated propulsion and power system can be considered as emergency generators, provided that class rules and regulation and legislation requirements for emergency generators are fulfilled.

Propulsion generators should be provided with means for obtaining the temperatures of the stationary windings, as shown in Table 16. The temperatures are to be displayed at a convenient location such as the main control console. A remote audible alarm actuated when thermal limits are exceeded should be provided. For machines with a heat exchanger type closed-circuit cooling method, either the flow of primary and secondary coolants or the winding temperatures should be monitored and alarmed. Liquid coolant leakage detection should be provided and alarmed if applicable. Such detectors should be provided for all sizes of propulsion generators and not limited to machines of certain sizes and rating.

Table 16 —Temperature measurement points – propulsion generator Sensor Stator winding temperature of ac generators Field winding temperature of dc generators Cooling air temperature Water leakage indicator a

b c

Location In each phase

Function Warning + trip

Comment In hot spota

Field winding

Warning + trip

In hot spota

Cold air Heat exchanger

Warning Warning

If water cooledb If water cooledc

Minimum one + one spare. 3-wire PT100 or equivalent. Warning + trip limit to be advised by vendor.

Minimum one + one spare per cooling circuit. 3-wire PT100 or equivalent. Warning limit to be advised by vendor.

Passive level switch.

15.5.2 Voltage control and generator excitation A standby unit should be provided for each type of automatic voltage regulator (AVR). For propulsion generators, manual voltage regulators should not be used. Harmonic distortions on the power system can affect the sensing circuits of some AVR systems so selection should ensure that the AVR system chosen is not particularly sensitive to harmonic distortions.

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Electric propulsion generators should be arranged so that propulsion can be maintained in case of failure of a generator excitation system or failure of a power supply for an excitation system.

If a propulsion system contains only one generator and one motor and cannot be connected to another propulsion system, more than one exciter with controller should be provided for both motor and generator as applicable. However, for self-excited generators, a duplicated AVR is sufficient.

There should be no automatic circuit-opening devices in excitation circuits except those affording shortcircuit or phase-failure protection for the main propulsion circuit. For the protection of the field windings and cables, means should be provided for limiting the voltage induced when the field circuits are opened.

When static excitation units are used, the arrangement of semiconductor fuses applied to protect diodes or thyristors necessary to protect the field coils against transient overvoltages should be such as to limit the protection to individual devices or groups of devices without opening the entire excitation circuit. Where fuses are used for excitation circuit protection, they should not interrupt the field discharge resistor circuit upon rupturing. Static excitation power supplies should comply with the requirements of IEEE Std 444 to the maximum extent practicable.

15.5.3 AC generators The generators should be sized to provide adequate load margin to guard against large load motors pulling out of synchronism during rough weather and while maneuvering. Power factor should be calculated for each particular application, and it should allow for the combined demands of the ship service load and the propulsion drive static power converters when operating at low ship speeds (high commutation angle).

15.5.4 DC generators DC generator armature voltage should not exceed 1000 V dc.

15.6 Propulsion drive transformers Static converter propulsion transformers should be designed and rated for starting and operation in an ASD without any degradation of the insulation, degradation of commutation, and derating.

All windings should utilize Class F or H insulation systems that resist moisture, oil vapor, and salt air. In lieu of detailed calculation of additional losses, e.g., due to harmonic currents, the windings should utilize a 55 °C temperature rise over the ambient temperature for liquid-filled transformers.

This clause is applicable as additional requirements to 10.2, to transformers whose main purpose is to feed main and excitation power to propulsion converters or auto transformers intended for continuous operation in relation to propulsion converters, e.g., for regenerative breaking. For auxiliary supply transformers, starting transformers, etc., 10.2 should apply.

Propulsion transformers should be evaluated where there is a need for the following, either alone or in combination: 

Adjusting voltage level from distribution system to propulsion converter voltage



Reducing harmonic distortion (e.g.,12-pulse, 18-pulse, 24-pulse configurations)



Reducing conductive born noise (e.g., EMI), using transformer with conductive shielding between primary and secondary 115 Copyright © 2017 IEEE. All rights reserved.

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

Separate motor drive circuits from distribution system’s grounding philosophy

Where these criteria are fulfilled without the use of a transformer, the propulsion transformer will normally be omitted.

Rating determination of the propulsion transformer should include the following:  Continuous operation at 105% of maximum continuous load of actual converter  Overload duty cycle as specified for propulsion converter, if any  Harmonic losses  Transformer rating should be according to IEC 60726, or applicable IEEE Std C57 series standards Enclosure should be protected against corrosion. Propulsion transformers with enclosure should be equipped with heaters, suitable to keep it dry when not connected. The heaters should be automatically connected when main supply is disconnected. A light indicator should indicate when heater power is connected.

When using air to water heat exchanger, double-tube water pipes should be used, of a material corrosion resistant to the cooling medium. Special attention should also be made to the minimum distances in any direction to ensure proper cooling and inspection/maintenance work.

Each part of the transformer enclosure should be grounded by a ground strap, or equivalent, to protective earth. Induced currents in enclosure or clamping structure during energizing or in normal operation should not cause arcing.

Propulsion transformers should have a copper shield between primary and secondary windings for reducing conductor borne noise and to reduce the risk for creepage and flashover between primary and secondary windings. This may be omitted when the converter is equipped with EMI filters at line supply, but then an overvoltage limiting device should be installed on the outputs of a step-down transformer.

The primary windings should be equipped with full capacity taps at 2.5% and 5% above and below normal voltage taps.

Sufficient space should be provided for termination of the required number of incoming and outgoing cables. Cables should be supported at a distance of a maximum of 600 mm.

Access panels for inspection or cable termination work should be bolted or locked. Locking of hatches that can be opened without a tool or key, e.g. handles, is not acceptable. The transformer should be clearly marked on enclosure and all access panels by the following warning signs:  If greater than 1000 V, “Danger High Voltage <voltage level>”  If lower voltages, “Danger—<voltage level>” Terminals for instrumentation should be separated from power supplies in a separate or in a twocompartment junction box with EMI suppressing device. The propulsion transformers should be equipped with the following instrumentation: 

Propulsion transformers should be provided with means for obtaining the temperatures of the windings, as shown in Table 17.



The temperatures are to be displayed at a convenient location such as the main control console.



A remote audible alarm actuated when thermal limits are exceeded should be provided.

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IEEE Std 45.1-2017 IEEE Recommended Practice for Electrical Installations on Shipboard—Design



For transformers with a heat exchanger type closed-circuit cooling method, either the flow of primary and secondary coolants or the winding temperatures should be monitored and alarmed.



Liquid coolant leakage detection should be provided and alarmed if applicable. Such detectors should be provided for all sizes of propulsion transformers and not limited to units of certain sizes and rating.

Table 17 —Temperature measurement points − propulsion transformer

Sensor Winding temperature Cooling air temperature Water leakage indicator Pressure switch a b c

Location Secondary windings Cold air Heat exchanger In transformer house

Function Warning + trip

Comment In hot spota

Warning Warning Trip

If water cooledb If water cooledc If liquid filled

Minimum one + one spare. 3-wire PT100 or equivalent. Warning + trip limit to be advised by vendor.

Minimum one + one spare per cooling circuit. 3-wire PT100 or equivalent. Warning limit to be advised by vendor.

Passive level switch.

Propulsion transformer pre-magnetization circuitry may be considered so that the transformer magnetizing current demand does not create adverse effect on the main power bus.

15.7 Propulsion motors 15.7.1 General Propulsion motors should be of substantial and rugged construction, and motor construction should be in accordance with Clause 13, with additional requirements described in this clause.

Static converter fed propulsion motors should be designed and rated for starting and operation in an ASD without any degradation of the insulation, degradation of commutation, and derating. All windings should utilize Class F or H insulation systems that resist moisture, oil vapor, and salt air. In lieu of detailed calculation of additional losses, e.g., due to harmonic currents, the windings should utilize a 55 °C temperature rise over the ambient temperature.

Propulsion motors should be enclosed and ventilated and should be provided with forced ventilation when required by the service. The exhaust air should be discharged through ducts from the motor enclosure.

These ducts should be arranged to prevent the entrance of water or foreign material. Ventilation may be provided by the recirculation of air through a closed or partially closed system employing water coolers.

Where the coolers are of sufficient capacity to provide 40 °C cooling air at the maximum condition, allowable temperature rises should be based on this ambient temperature. In this case, extreme care should be taken to prevent the water from entering the motor via leaking cooler tubes. The air entering the motors should be filtered to minimize the entrance of oil vapor and foreign material. Means should be provided for totally enclosing the motor when not in use if forced air-cooling is provided by external (in the weather) ventilation ducts. Abnormal brush wear and slip ring maintenance may occur in motors containing silicon materials. Silicon should not be used in any form that can release vapor in enclosed motor interiors.

Air ducts should be provided with high-temperature alarms, dampers, and means of access for inspection.

Dampers need not be provided for recirculating systems.

Common-mode voltages generated by the PWM inverters in VSD systems can introduce common-mode circulating currents. Means such as common-mode blocking filters or grounded shaft brushes should be considered to prevent circulating currents from passing between the motor shaft journal and the bearings.

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The lubrication of propulsion motor bearings and shafting should be effective at all normal speeds from continuous creep speeds to full speed, ahead, and astern. The shafts and bearings should be self-lubricated.

They should not be damaged by slow rotation, under any operational temperature conditions, either when electrical power is applied to the motor or when the propellers may induce rotation.

Pressure or gravity lubrication systems, if used, should be fitted with a low oil pressure alarm and provided with an alternative means of lubrication, such as an automatically operated standby pump, an automatic gravity supply reservoir, or oil rings.

If the insulation does not incorporate self-extinguishing material, provisions for a fire extinguishing system suitable for fires in electrical equipment should be provided for motors that are enclosed or in which the air gap is not directly exposed.

Effective means, such as electric heating, should be provided to prevent the accumulation of moisture from condensation when motors are idle.

Propulsion motors should be provided with means for obtaining the temperatures of the stationary windings, as shown in Table 18. The temperatures are to be displayed at a convenient location such as the main control console. A remote audible alarm actuated when thermal limits are exceeded should be provided. For machines with a heat exchanger type closed-circuit cooling method, either the flow of primary and secondary coolants or the winding temperatures should be monitored and alarmed. Liquid coolant leakage detection should be provided and alarmed if applicable. Such detectors should be provided for all sizes of propulsion motors and not limited to machines of certain sizes and rating.

Table 18 —Temperature measurement points − propulsion motor Sensor Stator winding temperature of ac generators Field winding temperature of dc generators Cooling air temperature Water leakage indicator a

b c

Location In each phase

Function Warning + trip

Comment In hot spota

Field winding

Warning + trip

In hot spota

Cold air Heat exchanger

Warning Warning

If water cooledb If water cooledc

Minimum one + one spare. 3-wire PT100 or equivalent. Warning + trip limit to be advised by vendor.

Minimum one + one spare per cooling circuit. 3-wire PT100 or equivalent. Warning limit to be advised by vendor.

Passive level switch.

15.7.2 Propulsion motor excitation For propulsion motors requiring external electrical excitation, each propulsion motor exciter should be supplied by a separate feeder.

There should be no overload protection in excitation circuits that would cause the opening of the circuit.

Static excitation power supplies for propulsion motors may be incorporated in the propulsion drive cabinets for the associated motor or may be in separate, free-standing cabinets in the drive or motor room. The standby propulsion exciter power supply should be physically and electrically isolated from the main excitation power supplies and should incorporate an output transfer switch to apply excitation power to the main propulsion systems.

Motor drive should be stopped and should reduce the motor voltage to zero after opening of the field circuit. In constant voltage systems with two or more independently controlled motors in parallel on the same generator, the motor circuit breaker should be tripped when the excitation circuit is opened by a switch or contactor.

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IEEE Std 45.1-2017 IEEE Recommended Practice for Electrical Installations on Shipboard—Design

15.7.3 AC propulsion motors Motors should be polyphase with a voltage between phases not exceeding 13.8 kV. The rating of the propulsion motor should consider the power needed to fulfill thrust requirements both for bollard pull conditions (dynamic positioning or maneuvering) as well as for sailing conditions. Propulsion motor torque, power, and speed characteristics should conform to the propeller characteristics provided by the propeller vendor.

15.7.4 DC propulsion motors The voltage of any single-motor armature should not exceed 1000 V. Where multiple motor armatures are used in series and the voltage exceeds 1000 V, the system should be such that one or more generators are interspersed between the armatures, or some other arrangement employed, so that the voltage between any two points of the system is reduced to a value not in excess of 1000 V. DC propulsion motors should have a 5% for 30-minute torque overload rating and should withstand 125% of rated armature current for 10 min and 200% of rated field voltage for 10 min. The motors should be furnished with commutating poles and compensating windings.

15.8 Propulsion power conversion equipment The propulsion power conversion equipment should fulfill applicable requirements, class rules, and regulations and comply with either IEC 60146 or design guidelines of IEEE Std 519 to the maximum extent practicable. The equipment should be designed for continuous operation within the maximum ambient and cooling water temperatures (if water-cooled) without reduction of the equipment’s rated performance criteria.

If drives are fitted with forced ventilation or water cooling, means should be provided to monitor the cooling system. In the case of a cooling system failure, the current should be reduced automatically to avoid overheating, or the converter may shut down if necessary. Failure of the cooling system or automatic reduction of current should be indicated by an audible and visual alarm in the engine control room and wheelhouse. The alarm signal can be generated by a reduction in the flow of liquid coolant, by loss of the electric supply to the ventilation fans, or by an increase in temperature of semiconductor’s heat sink or equivalent alternatives.

Drive enclosures and other parts subject to corrosion should be made of corrosion-resistant material or of a material rendered corrosion resistant.

The static power converters should be mounted in such a manner that they may be removed without dismantling the unit.

Propulsion drive enclosures shall have a protection equivalent to switchboard requirements (see 9.10).

Outdoor installations should not be accepted.

Whenever power converters for propulsion are applied to integrated electric plants, the drive system should be designed to maintain and operate with the power quality of the electric plant. The effects of disturbances, both to the integrated power system and to other motor drive converters, should be regarded in the design. Attention should be paid to the power quality impact of the following: 

Multiple drives connected to the same main power system.

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IEEE Std 45.1-2017 IEEE Recommended Practice for Electrical Installations on Shipboard—Design



Commutation reactance, which, if insufficient, may result in voltage distortion adversely affecting other power consumers on the distribution system. Unsuitable matching of the relation between the power generation system’s subtransient reactance and the propulsion drive commutation impedance may result in production of harmonic values beyond the power quality limits.



Harmonic distortion can cause overheating of other elements of the distribution system and improper operation of other power consumers.



Adverse effects of voltage and frequency variations in regenerating mode.



Conducted and radiated EMI and the introduction of high-frequency noise to adjacent sensitive circuits and control devices. Special consideration should be given for the installation, filtering, and cabling to prevent EMI.

The following propulsion drive unit protection should be provided:  Drive overvoltage protection by suitable devices applied to prevent damage.  Semiconductor elements in static power converters should have short-circuit protection, unless they are rated for the full short-circuit available at the point of application. When fuses are used for protection, blown fuse indication should be provided.  Load limiting control to ensure that the permissible operating current of semiconductor elements cannot be exceeded during normal operation.

The propulsion converter should be equipped with a blackout prevention function ensuring that it does not cause overload of the power generation system while ensuring power available to essential ship service loads. This should be effective in normal operations and after a fault in the power system, e.g., loss of one generator.

The propulsion converter should withstand or restart automatically after a short loss of power supply, e.g., after a cleared short-circuit in the power distribution system, if the propulsion unit is necessary to maintain the required maneuverability in the intended operation.

When maneuvering requires regenerative braking of the propulsion unit, the converter should either be equipped with load dumping resistors or regenerative line supply. Dimensioning of the dumping resistors and regenerative line supply should ensure safe dynamic operation of the vessel under all specified conditions, including crash-stop maneuver. Special attention should be made to the ability to regenerate power to the power system without causing excessive voltage and frequency variations, and the propulsion converters with regenerative line supply should provide means to limit the amount of regenerated power to a level that can be absorbed by the line network, as shown in Table 19.

Table 19 —Temperature measurement points − propulsion conversion equipment Sensor Cooling media temperature Cooling air temperature Water leakage indicator a

b c

Location Cooling media Cold air Heat exchanger

Function Warning + trip Warning Warning

Comment In hot spota If water cooledb If water cooledc

Minimum one + one spare. 3-wire PT100 or equivalent. Warning + trip limit to be advised by vendor.

Minimum one + one spare per cooling circuit. 3-wire PT100 or equivalent. Warning limit to be advised by vendor.

Passive level switch.

15.9 Main power switchboard Main power switchboards for electric propulsion and integrated plant applications should fully comply with the recommendations in IEEE Std 45.7.

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15.10 Propulsion control equipment Control consoles should be of substantial and rugged construction, and they should group all instruments, user displays, and control devices used in the operation and control of propulsion systems.

Means of control should be provided from the local drive control, engine control room, and navigation bridge. Whenever the equipment is arranged for control from two or more stations, a selector switch or equivalent should be provided for connecting the control means to the delegated station. Simultaneous control from more than one control station should not be possible.

Changing of the control station should be possible only when the control actuators (typically, levers) of the station in command and the incoming station are in the same position or when an acceptance signal set by the desired station is received. The transfer command must be issued, and control can be transferred only after acknowledgment from the new station in control is received.

The control system should be designed so that damage to equipment outside of the machinery space cannot prevent control from the control stations within the machinery space. Failure of power-assisted throttle controls, when used, should not result in an interruption of the power to the propulsion shaft, but should be indicated by an alarm.

All control means for operating prime movers, setup switches, contactors, field switches, and so on should be interlocked to prevent their incorrect operation.

In regulating systems with feedback control, duplex circuitry and components should be utilized to ensure a high degree of reliability. Failure of a control signal should not cause an increase in propeller speed. The reference value transmitters in the control stations and the control equipment should be designed so that any defect in the value transmitters or in the cables between the control station and the propulsion system will not cause an increase in the propeller speed.

The control of the propulsion system should be initially activated only when the assigned control lever is in the “zero” or “stop” position and the system has main and control power available and ready for operation.

Each control station should have an emergency stop device that is independent of the control lever. Where a navigating bridge and other remote propulsion control stations are installed, indicating lights should be provided at each control station to indicate which station is in control.

The control consoles should be designed with a structural steel frame, marine grade aluminum, or durable nonconductive material. Instrument panels should be made of sheet steel. The control consoles should be protected at the side and back with panels with ventilation louvers as required. A warning nameplate, giving the maximum voltage inside the enclosure, should be provided on all doors, providing access to the enclosure.

Means should be provided at each propulsion control console for continuously monitoring prime mover output power. Indication should be provided when current or power limiting is in operation.

The following instruments and meters should be mounted or be available in a graphical user interface on control consoles, as shown in Table 20.

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Table 20 —Propulsion control instruments and meters Main control room

Engine control room

a) For each prime mover: 1) Power (kW)

X

X

b) For each generator: 1) Armature current (A) 2) Armature voltage (V or kV) 3) Power factor (for ac generators)

X X X

X X X

c) For each power generation bus: 1) Frequency (Hz) 2) Available power

X X

X X

d) For each propulsion drive: 1) AC propulsion: i) Input current (A) ii) Motor power (kW) iii) Field current of synchronous motors (A) 2) DC propulsion: i) Armature current (A) ii) Armature voltage (V or kV) iii) Current in individual paralleled rectifier bridges (A)

e) For each propeller (as applicable): 1) Azimuth steering angle (degrees) 2) Rudder angle (degrees) 3) Speed indicator (propeller rpm)

Other control stations — —

—

— X X X

X X X

X X X

X X X

X

X

X

X X

X X

X X

The propulsion system control consoles should have at least the following indications for each propeller: a) System Ready: Power circuits and necessary auxiliaries are in operation and ready to accept control commands. b) System Fault: System cannot respond to control commands; propeller not under control. c) Power Limit: System disturbance. For example, loss of ventilation for propulsion motors or drives, loss of cooling water supply, or loss of motor power level limited due to insufficient generator capacity. Control commands restricted.

If the main control console is not located in the engine room or if the prime-mover gauges cannot be conveniently read from the control console, principal prime-mover parameters should be displayed at the main control console. A clock with digital display fed from the control system master clock should be mounted in each control console.

All ammeters and wattmeters should be marked in red at the rated value of the circuit in which they are connected. Metal cases of instruments should be grounded. Secondaries of all instrument transformers should be grounded.

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Control transfer capability should be incorporated in the drive control section, with local manual transfer switching at the drive and remote transfer capability from the engine room console. Emergency local control should be included in the drive control section or from a separate control panel in the propulsion room. Emergency control shall be independent from remote control system.

A framed wiring diagram showing the complete propulsion system schematic should be located near the main control console, and alternately be presented in the graphical user interface.

15.11 Power management For power systems consisting of generators operating in parallel, there should be an intelligent electronic device (computer system) for automatic power management, which will ensure adequate power generation to meet safe propulsion requirement. The power management system should control load sharing between on-line generators and execute load reduction or load tripping of nonessential loads when the power plant is overloaded.

The machinery control system should be designed to prevent overloading the prime mover and the generators by limiting the propulsion power. The load limiting circuits should ensure that essential requirements of the ship service system have priority over propulsion.

NOTEâ&#x20AC;&#x201D;Some operational conditions may require sharing of reduced propulsion speed for safe operation of the vessel.

An audible and visual alarm should be installed at each throttle location and should operate when the load limiting circuitry restricts the available propulsion power/current in order to maintain power to essential ship service loads.

Where the electrical system arrangements permit a propulsion motor to be connected to a generating plant having a continuous rating greater than the motor rating, means should be provided to limit the continuous input to the motor to a value not exceeding the load capability of the propulsion unit.

15.12 Podded propulsion 15.12.1 General Podded propulsion systems consist of a housing located under the hull of the vessel that is either electrically or mechanically powered. The pod may be steerable or fixed. A steerable-podded propulsion unit constitutes both propulsion machinery and the steering system.

The requirements for podded propulsion in the IEC 60092 series of standards are recommended.

15.12.2 Steering system If the pod is used as a steering device, class and regulatory requirements for steering systems shall apply for the pod steering system and the term rudder angle should be interpreted as pod azimuth angle. The pod steering system should be an electrohydraulic or electrical type.

The podded propulsion unit should be provided with a dual redundant steering system. If more than one azimuthing pod is provided, each shall have a fully independent steering system. The steering system should be capable of moving, stopping, and holding the pod unit at any desired angle within design limits.

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IEEE Std 45.1-2017 IEEE Recommended Practice for Electrical Installations on Shipboard—Design

Clause 16 provides additional requirements as applicable.

15.12.3 Shaft, bearing, sealing systems, and the propellers Provisions for continuously or regularly monitoring shall be installed. If water leakage in shaft sealing may penetrate into the vessel’s hull, the water shall be collected in a bilge system equipped with pumps.

15.12.4 Auxiliary systems All essential auxiliary systems shall be placed as close to the pod unit as possible. They shall be monitored and supplied from at least two different sources of electrical power for redundancy purposes.

15.12.5 Electrically powered pods 15.12.5.1 Electric motor The electric motor can be an induction (asynchronous) motor, a synchronous motor, or a dc motor. If the vessel is equipped with only one podded propulsor, the motor should consist of at least two electrically independent winding systems.

The electric motor should be designed in accordance with 15.7.

15.12.5.2 Power transmission system Power transmission between rotatable and fixed unit components shall supply power continuously by either slip ring assembly or flexible cable. If slip ring units are used, it shall be possible to install provisions for detecting sparking. The brushes shall be visible for inspection during operation. The degree of protection shall be at least NEMA 4x or equivalent IP enclosure. Flexible connection for fluids shall be avoided. Any damage to the fluid connection shall not lead to liquid penetration to essential electrical equipment.

15.12.5.3 Ventilation and cooling unit Ventilation and cooling systems should ensure that under maximum operating conditions, the electrical motor will not exceed the maximum temperature limits. The systems should be designed so that a single failure of the ventilation and cooling system will not lead to loss of propulsion power. The ventilation systems shall be monitored for proper operation. The air flow into the electrical motor should be filtered, and other measures be taken to avoid accidental intake of foreign bodies.

15.13 Propulsion cables Propulsion cable and cable installation should be as recommended by IEEE Std 45.8. Special considerations should be made to the harmonic losses and for attenuation of EMI when selecting cable, as recommended by the vendor of the propulsion converter. Propulsion cable should not have any splice or joint. For parallel-connected semiconductor devices, an equal current distribution should be ensured.

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15.14 Propulsion equipment location Equipment should be located where it will not be exposed to mechanical damage or to damage from water, heat, steam, or oil. Equipment should be placed in well ventilated compartments in which flammable gases and acid fumes cannot accumulate. Consideration should be given to locating the main power switchboard such that it will not be damaged in case of collision or grounding of the ship. The machinery should be arranged to provide ample access for inspection, adjustment, disassembly, and repair. A watertight well, with a provision for draining, should be provided around the base of the propulsion motors. Equipment should be located to avoid damage from bilge water. For purposes of motor inspection and repair, provision should be made for access to the stator and rotor coils, and for the withdrawal and replacement of field coils.

15.15 Ventilation All areas of the engine room, propulsion equipment rooms, and motor rooms should be thoroughly ventilated to avoid hot air pockets. Gratings should be used where deck plates would interfere with proper ventilation of the electric machinery. Main control rooms should be air-conditioned. When ventilation ducts are provided, they should be so arranged that water or foreign material from outside is not directed at the machinery.

15.16 Bed-plates and foundations Bed-plates, sub-bases, feet of propulsion motors, and pod assemblies should be of rugged construction, arranged for the specified fasteners, and secured to the structural foundations. Generators and associated prime movers should be resiliently mounted to their foundations if required for noise and vibration purposes.

Switchboards, power converter cabinets, and control consoles should be secured to a solid foundation and may be either self-supporting or braced to the bulkhead or deck above. When braced to the deck above, the bracing should be flexible to allow deflection of the deck without buckling the assembly structure. Units should be located away from, or protected against, sources of dripping liquid.

15.17 Lubrication Propulsion motors using forced external pressure or gravity lubrication for bearings should be provided with an independent spare lubricating oil pump. Where oil coolers are used, two separate means should be provided for circulating water through the coolers. An alarm system should be installed in connection with all external lubricating oil systems (see IEEE Std 45.2). Systems depending on forced lubrication, pressure, or gravity should be arranged to shut down automatically on loss of oil pressure. The oil discharge from each forced lubricated main bearing should be visible. The lubricating oil system should be designed to prevent oil from coming in contact with parts having a temperature in excess of 343 °C. Means should be provided to determine the temperature of oil leaving bearings.

Lubricating oil cooling should be provided. Extreme care should be taken to prevent the contamination of the oil supply by water or other extraneous matter, and the cooling water pressure should be less than the oil pressure. Oil filters or separators should be installed. The flash point of the lubricating oil should in no case be below 175 °C. Oil guards should be provided if necessary to prevent oil from creeping along the shaft to machine windings.

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Precautions should be taken to prevent oil vapors from passing into the generator windings. Openings in machines for oil vents and thermometer wells should be constructed so that vapor cannot escape into the windings.

The propulsion motor bearings and shaft bearings should lubricate and operate successfully in all operating speeds.

15.18 Fire extinguishers In addition to any fixed fire extinguishing systems, portable fire extinguishers should be provided in the vicinity of propulsion equipment.

16. Steering systems 16.1 General An automatic steering control system consists of the following apparatus: 

A heading data sensor consisting of a gyrocompass, a sensor equipped magnetic compass, or both



A device for defining the prescribed course



Error sensors to measure the difference between the actual heading and prescribed courses



A heading control system



A rudder position indicator and rate of turn indicator



A rudder control system



Power supplies for the automatic steering control system



An alarm circuit to indicate electrical supply failure or other major malfunction, including divergence of the actual and prescribed course by more than a set amount



Additional circuits such as manual auxiliary rudder controls, override controls, or interfaces to navigation systems for the purpose of automatic changing of the prescribed course

In the past, the division between an autopilot (frequently referred to as a gyropilot) and the electric, mechanical, or hydraulic portion of the steering system that actually moved the rudder(s) was separate and distinct. The small size of the modern electronic autopilot permits the steering stand to include the manual wheel for follow-up steering, non-follow-up controls, steering pump controls, and indicators for rudder order and rudder position.

16.2 Navigating bridge installation The arrangement of the steering controls in the navigating bridge should provide full follow-up control of the rudder. In addition, the following installation details apply: 

The arrangement of the steering station should be such that the helmsman is abaft the steering device and can readily observe all steering indicators and controls.



A suitable notice should be installed directly in the helmsman’s line of vision, to indicate the direction in which the steering device must be turned for right rudder and left rudder.

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

There should be an indication at the steering station as to what steering control system and pumps are being used.

16.3 Power supply The steering control system power supply should be fed from the same feeder(s) as the steering gear (see 16.5).

16.4 Alarm system Required alarms (see 16.6.3 and 16.6.4) are frequently included in the autopilot stand.

16.5 Steering gear 16.5.1 General When the main and auxiliary steering gears are electrically powered and controlled or when an arrangement of two or more identical power units are utilized, the vessel should have two separate steering systems, each consisting of a power unit, steering control system, steering gear feeder, and associated cable and ancillary equipment. The two systems should be separate and independent on a port and starboard basis.

Each steering gear motor controller should include the following apparatus: 

Power input disconnect switch or non-automatic circuit breaker



Power available indicator light



Steering motor START/STOP pushbutton



Motor running indicator light



Steering control system power supply transformer



Steering control power supply transformer output circuit breaker having only an instantaneous trip



Control power available indicator light



Steering control power transfer switch, Local/Navigating Bridge



Steering motor overload alarm relay



Input power failure alarm relay



Control power failure alarm relay



Phase failure trip relay (for three-phase fused power sources)

16.5.2 Feeder circuits Vessels with one or more electric-driven steering power units should have at least two feeder circuits. One of these feeder circuits should be supplied from the main switchboard. On vessels where the rudder stock is required to be over 230 mm in diameter in way of the tiller (excluding strengthening for navigation in ice) and an emergency power source is required, the other feeder circuit should be supplied from the emergency 127 Copyright © 2017 IEEE. All rights reserved.

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IEEE Std 45.1-2017 IEEE Recommended Practice for Electrical Installations on Shipboard—Design

switchboard or an alternative power supply. Where an alternative power supply is provided, it should be available automatically within 45 s of loss of power supply from the main switchboard, be located in the steering gear compartment, and be used for no other purpose. The alternative power supply should have capacity sufficient for one-half hour of continuous operation of the rudder from 15° on one side to 15° on the other side in not more than 60 s, with the ship at its deepest sea-going draft while running at one-half of its maximum ahead service speed or 7 knots, whichever is the greater.

Vessels that have a steering gear with two electric motor-driven power units should be arranged so that one power unit is supplied by one feeder and the other power unit is supplied by the other feeder. Each steering gear feeder circuit should be separated as widely as practicable from the other and should have a disconnect switch in the steering gear room. Each feeder circuit should have a current-carrying capacity of 125% of the full-load current rating of the electric steering gear motor or power unit plus 100% of the normal current of one steering control system, including any associated motors.

The overcurrent protection for each steering gear circuit at the main and emergency switchboards should be an instantaneous circuit breaker set to trip at not less than 200% of the locked rotor current of one steering gear motor plus other loads that may be on this feeder for ac installations. For dc installations, the instantaneous trip should be set not less than 300% and not more than 375% of the rating of the steering gear motor. No other overload device or fuse that will open the power circuit should be provided in the motor or control circuits.

The opening of the main or emergency switchboard steering gear circuit breaker should operate audible and visual alarms located at the main propulsion control station and the navigating bridge.

Each steering gear motor circuit should be equipped with an overcurrent relay to operate audible and visual alarms located at the main propulsion control station and the navigating bridge. No other functions should be performed by this relay.

The steering gear motor circuit should be capable of accelerating the motor under a torque requiring a current of 150% of motor rating. If the inherent design of the steering gear does not prevent overhauling of the rudder, a magnetic brake should be installed.

A pilot light for each steering gear motor to indicate motor running should be provided at the main propulsion control station and the navigating bridge. This pilot light should be fused.

16.5.3 Direct-drive steering gear The control for direct-drive ac steering motors should be of the solid-state, reversible, variable-speed drive type. For direct-drive dc motor installations, the control may be rheostatic or variable voltage. These controls should include step-back overload protection without opening the circuit.

16.6 Steering control systems 16.6.1 General Electric control may be of the self-synchronous “follow-up” type or “non-follow-up” type.

The follow-up type uses a remotely controlled servomotor that, by means of signal feedback, gives a definite rudder position for each steering wheel position. A follow-up control system may be provided that produces at the steering gear machinery a motion and positioning that is in synchronism with the position and motion of the steering wheel in the remote location.

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The non-follow-up type electric control consists of a master switch with spring return to the OFF position, which gives right or left rudder motion. Rudder motion is continuous in the direction indicated, until the limits of travel of the rudder are reached or the master switch returned to the OFF position. The rudder remains in the last ordered position until the master switch is moved from the OFF position.

Any of these electrically powered systems may function in conjunction with automatic steering systems (see Clause 16).

16.6.2 Steering control system installation Each steering power unit should have at least one steering control system capable of being operated from the navigating bridge. Additional control stations may be provided as required elsewhere on the ship. Each steering control system on vessels of 300 gross tons and above should be arranged so that each steering gear power unit can be controlled in the steering gear room. A selector switch should be provided in the navigating bridge for delegating the control to any one of these stations. All circuits from each steering station should be entirely disconnected by the selector switch, except those circuits to the station in use. A rudder angle indicator should be provided at each such station (see IEEE Std 45.2).

The steering control system for a steering power unit should be separated as widely as practicable from each other steering control system and each steering power unit that it does not control.

Each navigating bridge steering control system should have a switch in the navigating bridge that is arranged in such a way that one action of the switch’s handle automatically puts into operation a complete steering control system and associated steering power units. If there is more than one steering control system, this switch should be as follows: 

Operated by one handle



Arranged so that each one individually or both steering control systems and all associated steering power units can be energized from the navigating bridge



Arranged so that the handle passes through an “off” position when transferring from one steering control mode to another

Arranged so that the switches for each system are in separate enclosures or separated by fire-resistant barriers Each steering control system should receive its power from the feeder circuit for its steering power unit in the steering gear room and have a switch that is in the steering gear room and disconnects the steering control system from its power source. Each motor controller for a steering gear should be in the steering gear room and have low voltage release. A means should be provided to start and stop each steering gear motor in the steering gear room. 

16.6.3 Steering indication and alarm system A steering indication and alarm panel should be installed at the main propulsion control station and in the navigating bridge. The following items should be provided: a)

A motor running indicator light for each steering power unit

b)

A control power available indicator light for each steering control system

c)

Visual and audible alarms for: 1)

Low oil level in each hydraulic oil reservoir

2)

Steering power unit motor overload

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3)

Power supply failure to steering power unit

4)

Power supply failure to steering control system

5)

Hydraulic lock-mismatch of steering order with steering machinery response signal

A common audible alarm may be used in conjunction with individual visual alarm indicators. Steering indication and alarm functions may be included with other vital alarm functions in a common panel or console, but should be grouped and clearly marked as steering system alarms.

16.6.4 Steering failure alarm system Each vessel that has power-driven main or auxiliary steering gear should have a steering failure alarm system that actuates an audible and visible alarm in the navigating bridge when the actual position of the rudder differs by more than 5° from the rudder position ordered by the follow-up control systems for more than: 30 s for ordered rudder position changes of 70° 6.5 s for ordered rudder position changes of 5° The time period calculated by the following formula (Equation (3)) for ordered rudder position changes between 5° and 70°:  R  = t   + 4.64  2.76 

(3)

where: t R

is the maximum time delay in seconds is the ordered rudder change in degrees

The alarm system should be separate from, and independent of, each steering gear control system, except for input received from the steering wheel shaft.

Each steering failure alarm system should be supplied by a circuit that meets the following conditions:  Is independent of other steering gear system and steering alarm circuits  Is fed from the emergency power source through the emergency distribution panel in the navigating bridge, if installed  Has no overcurrent protection except short-circuit protection by an instantaneous fuse or circuit breaker rated or set at 300% of either the current-carrying capacity of the smallest alarm system interconnecting conductors or the normal load of the system

17. Lighting equipment 17.1 General Each interior lighting fixture not located in a wet or damp location should be certified to UL 153, UL 924, UL 1570, UL 1571, UL 1572, and UL 1598, as applicable. Additionally, exterior lighting and interior

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lighting in a wet/damp location should be certified to UL 595-1985, UL 924, UL 1570, UL 1571, UL 1572, and UL 1598, as applicable. See Clause 27 for guidance on lighting fixtures in hazardous locations.

No fixture should be used as a connection box for a circuit other than the branch circuit supplying the fixture.

Watertight lighting fixtures should be utilized when located in the following areas:  In the weather  Mounted exposed to splashing water  Refrigerated compartments  Chain lockers (when permanently illuminated) Each fixture mounted in a damp location should at least be drip proof.

Fixtures should be ruggedly constructed and not susceptible to component loosening due to vibration.

Incandescent dome fixtures should be ventilated and designed so that none of the surrounding material is directly exposed to the heat of the lamps.

Each fixture and lamp holder should be permanently installed. Each pendant-type fixture should be suspended by and supplied through a threaded, rigid conduit stem. Each table lamp, desk lamp, floor lamp, and similar fixture should be secured in place so that it cannot be displaced by the roll or pitch of the vessel.

Exterior lighting should not interfere with required navigational lighting and should not impair night vision from the navigating bridge.

17.2 Location The preferred location for fixtures for general lighting is on the overhead, except where decorative lighting is desired for special effects. The fixtures should be located for maximum protection. When located on bulkheads, they should be approximately 1.8 m above the deck.

An indicator light should be installed outside each refrigerated space to show when lights in the refrigerated space are energized.

17.3 Provisions for portable lighting Receptacles for portable lights and similar equipment should be provided in or near chain lockers, deck machinery, steering gear, machinery spaces, shaft alleys, refrigeration spaces, and similar locations.

Receptacles located where they could be exposed to moisture should be watertight. Non-watertight receptacles may be used in baggage rooms, mailrooms, deck lockers, storerooms, passenger and crew accommodations, deck fan rooms, and similar places. Portable lights should not be used for built-in berths.

Lights on beds or other furniture connected by portable cable should have the cable secured to the furniture to reduce the amount of loose cable to a minimum.

Means should be provided to effectively ground all external metal parts of portable lights, including desk lights.

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17.4 Permanent watertight fixtures Watertight fixtures installed in outside spaces should be constructed of corrosion-resistant material or have a corrosion resistant finish. The globe should be protected by a suitable guard. Watertight fixtures installed in inside spaces may have the junction box that forms a part of the fixture constructed of material suitably protected against corrosion, but the portion of the fixture containing the screw threads for the globe and guard should be constructed of corrosion-resistant material.

17.5 Permanent non-watertight fixtures Non-watertight lighting fixtures may be provided for interior locations, except where watertight fixtures are recommended. Non-watertight lighting fixtures provided for forecastle, deck houses (not used as living quarters), cargo spaces (when permanently illuminated), machinery spaces, steering gear rooms, windlass rooms, galleys, public bath and toilet spaces (when showers are installed), and similar spaces should be drip proof.

Incandescent dome fixtures should be ventilated and designed so that none of the surrounding material is directly exposed to the heat of the lamps.

17.6 High-intensity discharge lamp fixtures Fixtures connected to an ungrounded electrical system should have isolated winding type ballasts. Limit discharge lamp circuit voltage to 600 V rms. Ancillary equipment for high voltage installations, including inductors, capacitors, resistors, and transformers should be either totally enclosed in a substantial grounded metal container (which may form part of the lighting fixture) or placed in a suitable ventilated enclosure of noncombustible material or of fire-resisting construction.

CAUTION A notice “DANGER, HIGH VOLTAGE” should be placed for high voltage discharge lamps that are accessible to unauthorized persons. The word “DANGER” should be in block letters not less than 10 mm high and the words “HIGH VOLTAGE” in letters not less than 5 mm high. The letters should be painted red on white background, and the size of each notice should be not less than 64 mm × 50 mm overall.

17.7 Lighting for hazardous locations Lighting equipment and associated wiring should be in accordance with Clause 27.

17.8 Illumination 17.8.1 General Lighting design, maintenance considerations, testing, and illumination levels for any space should comply with ABS Guide for Crew Habitability on Ships, API RP 14FZ and API RP 14F, as applicable.

Except for cargo space lighting, and for lights mounted above the normal line of vision, such as those mounted high in machinery spaces, any single incandescent lamp of more than 60 W rating, or multiple

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lamps of these types of more than 60 W total rating installed in a single lighting fixture, should be enclosed in a diffusing shade or otherwise shielded to avoid excessive brightness.

Berth lights should be mounted to have minimum horizontal projection so that the light may not be covered with bedding.

There should be over-the-side lighting at each pilot embarkation station.

17.8.2 Lighting for cargo handling High-intensity lighting fixtures used for the illumination of cargo spaces, hatches, and cargo handling gear should be mounted at a sufficient height to be above the normal viewing field of persons on the working deck. Outside lighting for lighters, wharves, gangways, decks, and hatches should be from overhead. In cargo spaces, lights should be located to project on cargo ports and hatches.

17.8.3 Lighting for lifeboat and life raft area Each vessel should have floodlights for the illumination of lifeboat and life raft launching areas.

Floodlights should be located where they can be directed to illuminate launching equipment and the area for launching, from the stowage position to the water. Each floodlight should have a manual means of positioning that does not require the use of tools, and it should be connected to the supply circuit by a short length of flexible cord without the use of a plug and receptacle. The flexible cord should be constructed for extra hard usage. Each floodlight should be supplied from an emergency lighting circuit.

17.9 Searchlights 17.9.1 General Ship searchlights may be permanent or removable. They should be capable of elevating and rotating through their intended operating range. When two searchlights are provided, they should be mounted at the extreme sides of the vessel. When mounted in an area other than a bridgewing, they should be provided with remote operating controls and local operating controls.

17.9.2 Construction and installation Searchlight and searchlight controls should be watertight. Construction and materials should be appropriate for the mounting location. To permit immediate operation, searchlight covers should not be used. The control switch should be mounted close to the point of operation of the light.

Heat-producing controls and junction boxes should be mounted on metal bulkheads with ample ventilation space. Where mounting on a metal bulkhead is not practical, a backing of heat insulating material should extend 30 cm beyond the extent of the heat-producing equipment. Mounting should be sufficiently rigid so as to restrict vibration. A suitable cable clamping device should be employed where the cable enters the body of the light.

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17.9.3 Lifeboat searchlights Searchlights installed on lifeboats should comply with ASTM F1003-86. When the lifeboat has a cabin, the searchlight should be securely mounted to the top of that cabin. Where there is no cabin, the searchlight should be capable of being attached to a sturdy stanchion or other structure. Searchlights mounted on stanchions should be safely stowed when not in use. Mounting hardware should be adequately sized and corrosion-resistant.

The searchlight should be wired with a rubber-jacketed flexible cord constructed for extra hard usage, of a size not less than 16 AWG. The cord should be of sufficient length to permit rotation and elevation of the light.

17.10 Emergency lighting All emergency lights should have a distinguishing mark, such as a red “E,” for easy identification.

Emergency lights should provide adequate illumination, generally a certain percentage of normal illumination, to permit safe operation of the vessel, as well as emergency egress.

Each exit light required on vessels should have the word “EXIT” in red block letters.

NOTE—Class and flag state rules should be consulted before specifying solid-state lights for emergency lighting applications.

17.11 Nameplates Every lighting fixture should have a nameplate attached inscribed with the following data: 

Marine (name of apparatus)



Name of manufacturer



Type



Voltage



Amperes



Watts

17.12 Solid state lighting (SSL) 17.12.1 Introduction Solid-state lighting (SSL), known as light emitting diode (LED), is proven for shipboard lighting applications.

17.12.2 SSL LED system design features for shipboard application SSL LED system design features for shipboard applications are as follows:

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a)

Powering an SSL LED chip from an ac source requires a regulator to step-down to the correct voltage and current. Each lighting fixture typically uses multiple LED chips per fixture; however the higher quality LED products are a multi-volt product that spans the range from 120 V to 122 V.

b)

The SSL LED products shall be Third Party Safety Compliance Listed such as UL listed (or an equivalent Third Party Safety Compliance Listing such as CSA, IEC, or CE for non-U.S. applications). The SSL LED products shall be UL listed (or equivalent for non-U.S. applications).

c)

Porcelain or other brittle insulating materials should not be used for SSL LED lamp sockets for shipboard application where the material is rigidly fastened by machine screw or equivalent.

d)

For SSL LED luminaire shipboard illumination, heat dissipation, LED luminaire lens design, and EMI, counterplan by switching mode power supply (SMPS) should be conducted.

e)

SSL LED lamps shall be pre-wired with marine cable that complies with or is equivalent to IEEE Std 45.8 and IEEE Std 1580. The marine cable shall be completely sealed to the lamp body providing time saving at installation and reliable electrical watertight connection.

f)

Electromagnetic compatibility (EMC) − All SSL LED products are electronic devices. These electronic devices shall have electrical circuits containing components that suppress possible interference, both emission as well as susceptibility to emissions, to the limits as required by international standards.

17.12.3 SSL LED system nameplates Every SSL LED system should have a nameplate attached inscribed with the following data: a)

SSL LED lighting fixture 1)

Name of apparatus

2)

Name of manufacturer

3)

Type

4)

Operating voltage range (dc and ac)

5)

Lumen output

6)

Amperes

7)

Watts

8)

LED junction temp

9)

Warranty

10) Model and serial number 11) IP rating b)

SSL LED driver 1)

Name of apparatus

2)

Name of manufacturer

3)

Type

4)

Voltage

5)

Amperes

6)

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c)

SSL LED drive energy protection device (option) 1)

Name of apparatus

2)

Name of manufacturer

3)

Type

4)

Voltage

5)

Amperes

6)

Model and serial number

17.13 Navigation lights and signal lights 17.13.1 General Navigation lights and signals should meet the International Regulations for Preventing Collisions at Sea (COLREGS), except where modified by the authority having jurisdiction.

17.13.2 Navigation lights Each navigation light should be type-accepted by the authority having jurisdiction for the intended service.

Side, masthead, and stern lights should have dual light sources and should be controlled by a navigation light indicator panel located in the navigating bridge. Electric navigation light fixtures should be watertight.

If LED lamps are used, adequate protection should be used to protect for static and lightning discharge.

17.13.3 Signaling lights When a daylight signaling lamp (fixed or semi-fixed) is required by the authority having jurisdiction, the signaling light should be energized from an emergency lighting circuit. Each portable signaling light should be energized from a self-contained storage battery that can operate the light continuously for 2 h without recharging.

17.13.4 Navigation light indicator panel The navigation light indicator panel should provide audible and visual indication of failure of a lamp in use.

Where the authority having jurisdiction requires a secondary light source, there should be a means for immediate transfer to the second light source. It should be possible to silence the audible signal while the visual signal remains.

Each navigation light source is to be fed by an individual branch circuit with each insulated conductor controlled and protected either by a switch and fuse or circuit breaker. The overcurrent protection on the feeders should be at least twice the capacity of the overcurrent protection devices of the navigational light panel. The navigation light panel shall be fitted with main over-current devices rated or set greater than the maximum loading including spares of the panel for each feeder.

A recommended circuit diagram with a dual power source to supply the navigation lights is shown in Figure 7.

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MASTER SECTION

INDIVIDUAL LIGHT CIRCUIT TRANSFER SWITCH WITH OFF POSITION

MASTER SWITCH

SUPPLY BUS Indicator Light

Buzzer or Audible Device

BUZZER BUS 3A Fuse or Circuit Breaker

Watertight Grounded Double Receptacle

Two Compartments Running Lights

Watertight Plugs

Figure 7 —Semi-automatic navigation light panel

18. Whistle and siren control systems There should be a mechanical means for operating the ship’s whistles from the navigating bridge regardless of other systems installed. The manual actuating lead should be as direct as possible, amply protected, and when suspended for more than 4.5 m, supported by corrosion-resistant hardware. The system should be provided with ample corrosion resistant springs to counteract the force on the lever and to ensure the proper functioning of the system.

When electrically operated whistles and sirens are installed, all parts should be independent of the mechanical system. If a motor-operated timer is installed, particular attention should be given to its construction and location so that it will be inaudible in the navigating bridge and will not affect the magnetic compass. The power supply for the vital electrically operated whistles and sirens should be taken from the emergency power system.

When an electrically operated actuating valve is located more than 1.5 m from the whistle, an automatic drain feature for the whistle steam/air supply pipe should be installed.

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19. Heating equipment 19.1 Construction Heaters should be designed and constructed to heat the surrounding air by convection. They may be blower type design, where air is forced through the heating element by a fan integral to the heating unit. Heaters should be certified to UL 1042, UL 1278, and UL 2021, as applicable. Heaters in accommodation, machinery, and service spaces should meet the following requirements in Table 21.

Table 21 —Heater voltage and power requirements Location

Max rating (V)

Accommodation spaces (bulkhead mounted)

240

Machinery and service spaces

575

Power requirements

Number of heating elements

1500 W or less

1

Above 1500 W

2 or more

Heater construction should be strong and durable, with all parts solidly built to withstand vibration under service conditions. The framework should be of substantially proportioned metal, with parts securely fastened together. Heaters should have nonflammable insulating material, or adequate air circulation, between the heater and the mounting surface or between the heater and adjacent surfaces. Portable heaters should have a suitable clip or bracket fitted to retain the heater in a fixed position.

Heaters mounted on or adjacent to decks or bulkheads should be protected by perforated or expanded metal coverings or the equivalent. The ends, back, and top of these heaters may be solid material.

Heaters with exposed surfaces mounted flush with bulkheads should protect the elements with a screen or guard of perforated or expanded metal. The remaining sides of these heaters should be protected by a solid metal enclosure designed to meet recommended temperature limitations in 19.4 Heaters mounted on bulkheads should have the heater top slanted or otherwise designed to prevent the hanging of towels or similar flammable material on the heater. The protecting guard should be strong enough to resist being forced against current-carrying parts and to provide protection against electrical or mechanical injury. The heater openings should be sized small enough to prevent heating elements from being short-circuited or damaged by accident. All metal parts of the heater should be suitably protected against corrosion.

19.2 Heating elements Heating elements should be of the enclosed type with the element jacket constructed of corrosion-resistant material. Heating elements should utilize uniform units, easily installed and replaced. The heating element material should not corrode or oxidize. Alloys containing zinc are not recommended for this purpose.

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Heating elements should not be constructed of flammable material. All heating element connections should be accessible and designed so that they will not loosen due to vibration. Heating element supports should be wired to a terminal block with the connectors and leads brought out through insulating bushings. All insulating parts should be unaffected by heat from the heating elements.

19.3 Control switches A suitable regulating switch mounted on an approved insulating base should be provided. Heaters should be equipped with manual reset type thermal cutouts to prevent overheating of the elements.

Thermostatically controlled contactors should be provided for multistage heaters.

19.4 Temperature Heater enclosure case temperatures should not exceed that shown in Table 22.

Table 22 —Heater case temperatures Type heater

Maximum enclosure case temperature (°C)

Flush type

90

All others

125

NOTE—Reduction in surface temperature in compliance with UL 2021.

19.5 Nameplates Every heater should have a nameplate attached inscribed with the following data: 

Marine (name of apparatus)



Name of manufacturer



Type



Voltage



Amperes



Watts



Model and serial number

19.6 Electrical heat trace (EHT) The electrical load due to EHT used on vessels performing Arctic Polar Marine Applications can be very large so it is recommended that the electric plant load analysis (EPLA) include the EHT electrical loading on the power system during winter conditions. A suggested reference document is “Electrical Heat Tracing for Surface Heating on Arctic & Polar Vessels To Prevent Snow & Ice Accumulation” [B5].

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20. Galley equipment and workshop equipment 20.1 Electric cooking equipment 20.1.1 Construction All electric cooking equipment, attachments, and devices should be of rugged construction and designed to permit complete cleaning, maintenance, and repair. All servicing should be possible from the front or top without moving the equipment. Range, grill, oven, broiler, and griddle units should be sectional. Equipment should be rigid and self-supporting. Joints between equipment sections should be bolted. Equipment should be certified to UL 197, or the equivalent shipboard equipment requirements of a nationally recognized testing laboratory.

WARNING All external surfaces of cooking equipment, exclusive of cooking tops, should be thermally insulated to improve efficiency and help reduce the risk of burn hazard to personnel. The use of personal protective equipment is recommended when working with potentially hot surfaces.

Electric cooking appliances should be constructed so that parts that must be handled cannot become heated to a temperature exceeding the values given in Table 23.

Table 23 —Temperature limits for non-cooking surfaces on cooking equipment Handles, grips, and so on, made of: Metal Porcelain and material, molded rubber, or wood

vitreous material,

Maximum temperature during normal use held in hand (°C) For long periods

For short periods

55

60

65

70

Higher temperatures may be acceptable for parts that normally will not be handled with unprotected hands, such as handles of drawers for spilled liquid in cooking ranges.

All component parts should be made of corrosion-resistant material, or they should be adequately protected against corrosion. Unit exteriors should be stainless steel, or they should have baked enamel, or other corrosion-resistant finish. Chrome nickel stainless steel is preferred for cleanliness and maintenance. Oven linings should be chrome nickel stainless steel or aluminized steel.

Doors on electric cooking equipment should be equipped with heavy duty hinges and a locking device to prevent door opening in a heavy sea. Grab rails should be provided on the front of cooking equipment for use by the crew in heavy seas.

Portable cooking appliances should be weighted or shaped so that they cannot easily overturn.

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20.1.2 Mounting If the unit is to be platform mounted, the platform edges should not extend beyond the unit and a base should be provided that prevents the accumulation of foreign matter. All equipment should be mounted to prevent dislodgment by rolling or pitching.

20.1.3 Electric power Electric cooking equipment should be designed to operate on a standard voltage, not in excess of 600V, single- or three-phase. The individual phase loads of the heating elements in ac cooking equipment should be given on the equipment wiring diagram to facilitate adjustment of the overall galley phase balance.

Noncurrent-carrying metal parts of cooking equipment should be suitably grounded.

20.1.4 Heating elements All heating elements should be of the metal-clad enclosed type. No open and exposed resistance wire should be used. Porcelain may be used to seal the end of a sealed unit and to obtain proper creepage distances on the unit terminal. There should be a positive locking device to prevent element loosening due to vibration.

20.1.5 Wiring For ranges, ovens, and broilers built as independent units, wiring between the terminal blocks of the unit and the terminal blocks of the switchbox should have tinned stranded copper conductors and Class H insulation. Type MI cable also may be used for connections between appliance and switch box. All wiring should be adequately supported and protected from mechanical damage.

20.1.6 Controls All controls for ranges, ovens, and broilers, excluding thermostats, should be mounted in a separate drip proof switchbox located on or adjacent to the unit. The section of the switchbox that covers contactors should be hinged and equipped with a locking device. Other front access panels should be secured with screws to prevent accidental opening. Connections for external wiring should be made at suitably identified terminal blocks. A switchbox located on the unit should be insulated and ventilated to prevent damage to any of the controls or wiring.

Controls for fry kettles and griddles may be located on the units or on a remote control panel. When located on the unit, they should be as far from sources of heat as possible, protected against spillage and grease, and accessible with a minimum of disassembly. Fry kettle controls should be located in positions where the user does not have to reach over the cooking area to operate a control device. If controls for fry kettles and griddles are remotely located, they should be similar to those described for ranges.

The type of control and the temperature range for various appliances should conform to the guidelines of Table 24.

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Table 24 —Type of control and temperature range for appliances Service

Temperature range (°C)

Indicating 3 heat switch or thermostat with OFF position range top hotplates

90−230

Indicating 3 heat switch or thermostat with OFF position range griddle-hotplates

110−480

Indicating 3 heat switch or thermostat with OFF position range over compartment

110−480

Thermostat and separate indicating 3 heat switch for both upper and lower units

90−260

Rangetop griddles

Range oven boiler Top unit 3 heat switch

90−230

Fry kettle Indicating reversible switch and thermostat

90−230

Griddle Thermostat with OFF position or 3 heat switch

90−230

Thermostats for ranges should be mounted on the units and be adequately protected against spillage, grease, and mechanical injury. An automatic temperature control should be located on the unit in a position accessible for setting by the operator. The contactors controlling the power supply to the heating element should be located in the control panel. Broilers built as independent units (that are not combined with range type ovens) need not be furnished with thermostats.

Switches for ac service should be rated at not less than 30 A. A temperature-regulating thermostat whose failure will not result in a fire hazard should be capable of operating for a minimum of 30 000 cycles under full load. A combination temperature regulating and limiting thermostat that serves to prevent a fire hazard under abnormal operating conditions should be capable of operating a minimum of 100 000 cycles.

Rotary switches for operation with dc power should be capable of at least 50 cycles of operation at 125% of rated current, at rated voltage, and 6000 cycles of operation in each direction at rated current and voltage, without failure. Switches controlling relays and other similar functions should have a continuous rating at least equal to the circuit load.

Control circuits should be protected in accordance with 4.31.1 of IEEE Std 45.2-2011. Where the power input voltage is over 250 V ac and a lower control voltage is required, control power should be derived internal to the circuit. The control circuit should be de-energized when the power circuit is opened.

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20.1.7 Range tops and griddles To ensure positive grease collection, drip pans should be fitted under, and should project out from, the cooking surfaces, or the cooking surfaces should be equipped with grease deflecting baffles. Any spillage from the drip pan due to rough seas or handling should drain out the front of the unit. The unit should be designed so that spillage cannot flow to any place where it cannot be readily removed. Adequate drip pan drainage should be provided. Ranges should be provided with sea rails with adjustable barriers to prevent cook pot movement.

Griddles may have either heat selection switches or automatic temperature controls but need not be provided with both.

Heating elements should be removable from the top or front of the appliance without disassembly of the units.

20.1.8 Ovens and broilers Each section should be independently operated with provision for controlling the amount of top and bottom heat. Broilers should be designed to permit stacking one above the other on a cabinet base or an oven.

Back-shelf broilers should be designed to permit mounting on the rear of a range and should have at least 75 mm movement of controlled adjustable griddle height, where three heat switches are used.

Heating elements should be removable from the front without disassembly of the unit.

Broilers should be provided with rugged, movable grids, each provided with a counterbalanced means to vary the grid height approximately 150 cm, where heat selection switches are used and a positive stop to retain the grid at the desired height is provided. Where automatic temperature controls are provided, stationary grids with a positive stop should be provided. A removable drip pan should be installed beneath the grid. A second drip pan should be installed at the bottom of the broiler compartment for positive grease collection and easy removal.

20.1.9 Fry kettles A fry kettle unit may be a sectional (body, legs, and fat container) or a one-piece design. The fat container should be fabricated from corrosion-resistant material and should have adequate capacity to accommodate foaming. The bottom of the fat container should drain toward the center and should have a minimum 25 mm diameter drain pipe with block valve, arranged to provide straight through drainage with minimum clogging.

Fry kettle fat containers having a weight, when full, of 11 kg or more should not be movable manually but should be provided with a drain pipe and valve for grease drainage.

The heating elements should be controlled by an indicating reversible switch and thermostat and be removable from either the top or front of the fry kettle unit with a minimum of disassembly.

20.2 Motor-driven equipment Motor-driven equipment, such as dough mixers, meat grinders, and potato peelers, should be rigidly constructed and self-supporting. All component parts should be made of corrosion-resistant material or should be adequately protected against corrosion. All equipment should be designed for easy cleaning and servicing from the front.

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Motor-driven appliances should be certified to UL 73, UL 471 (refrigerators), UL 921 (dishwashers), and UL 399 (water coolers), as applicable.

Motors and controls for motor-operated appliances located in damp or wet locations should, where practical, be watertight or placed in watertight enclosures. Controls should be of heavy-duty construction.

Where it is impractical to obtain appliances with watertight motors and controls, appliances with standard commercial motors and control enclosures may be used.

20.3 Nameplates Every appliance should have a nameplate attached, inscribed with the following data: 

Manufacturer’s name and address



Equipment model designation



Red voltage(s)



Current



Number of phases



Frequency

21. Electrical power system protection 21.1 Overview Electrical power system protection is an electrical power system function for detecting faults, localizing faults, isolating faults, and reconfiguring the system to restore power to the maximum number of loads.

Goals of electrical power system protection include meeting QoS objectives, maintaining crew safety, and preventing cascading damage to power system equipment and load equipment. The electrical power system protection is typically implemented through the integrated response of the electrical power system supervisory controller and the electrical power system components.

21.2 Electrical power system protection elements 21.2.1 Fault detection and classification An integrated electrical power system should detect and classify electrical faults or failures.

Faults should be classified as one of the following: 

Overcurrent



Ground



Line to line

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

Internal equipment



Loss of phase



Other

21.2.2 Fault localization Once a fault is detected, the power system should identify the fault’s location and the power system component or load that has failed.

21.2.3 Fault isolation Once a fault has been localized, fault isolation should disconnect the failed power system component or load from the remaining non-faulted power system. Cost considerations could result in situations where a power system can disconnect a failed component only by also disconnecting undamaged equipment and loads. The power system should be designed to segregate loads sufficiently to ensure that the QoS requirements for undamaged loads are met. Note that in special cases, such as when continued operation is necessary in an ungrounded system with a single line-to-ground fault, fault isolation may be delayed in the determination of the operator.

WARNING Use segregated loads in medical spaces where loss of power could result in a risk of injury or death of a patient.

In systems critical to the safety of the vessel (e.g., steering gear), consideration should be given to the impacts of isolating equipment from the power supply versus potential equipment damage with respect to the overall safety of the vessel.

21.2.4 System reconfiguration Once a fault has been isolated, the electrical power system should be designed to reconfigure, if necessary, to ensure QoS requirements are met.

21.3 Electrical power system protection design 21.3.1 General The general requirements for shipboard electrical power system protection design should comply with IEC 60092-202 and should employ the IEC fail-to-safe principle, which states: “any failure should result in a safe situation, e.g., by a single fault in a circuit the faulty circuit is disconnected to be voltage free or without power.”

Power electronics should be designed to achieve the protection requirements of IEEE Std 1662.

Careful consideration must be given to short-circuit protection and to the selection of the various protective devices to ensure proper interrupting capacity and coordination regardless of their location in the vessel.

The overcurrent protective devices should provide high-speed clearance of low-impedance faults for ac systems and low resistance faults for dc systems so that fault currents of large magnitude will cause 145 Copyright © 2017 IEEE. All rights reserved.

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minimum damage to the system and equipment and minimize hazards. The overcurrent protective devices should also protect electric apparatus and circuits from damage under fault conditions through the coordination of the electrical and thermal characteristics of the circuit or apparatus and the tripping characteristics of the protective devices.

To achieve these basic objectives, each protective device should have an interrupting rating not less than the maximum short-circuit current available at the point at which the device is installed. Selective tripping should be provided between generator, bus tie, bus feeder, and feeder protective devices. In circuits supplying vital services, selective tripping should also be provided between feeder and branch circuit protective devices. A short circuit on a circuit that is vital to the propulsion, control, or safety of the vessel should be cleared only by the protective device that is closest to the point of the short circuit. A short circuit on a circuit that is not vital to the propulsion, control, or safety of the vessel should not trip equipment that is vital.

Protective devices should not be used beyond their interrupting capacity.

The maximum available short-circuit current should be determined from the aggregate contribution of all generators that can be simultaneously operated in parallel and the maximum number of motors that will be in operation and contribute to the short-circuit current.

When determining selective coordination characteristics, the designer must examine the impacts of multiple source and load configurations to ensure that the coordination requirements are met under all normal operating conditions.

21.3.2 Conductors Overcurrent protection by fuses or circuit breakers should be provided for all ungrounded conductors.

Fuses should not, and circuit breaker overcurrent trips need not, be provided for the neutral conductor of a three-wire grounded system, but provision should be made for feeder disconnect including the neutral.

The purpose of overcurrent protection for conductors is to open the electric circuit if the current reaches a value that will cause an excessive or dangerous temperature in the conductor or conductor insulation. A grounded conductor is protected from overcurrent if a protective device of a suitable rating or setting is in each ungrounded conductor of the same circuit.

21.3.3 AC systems The maximum available short-circuit current should be determined from the aggregate contribution of all generators that can be simultaneously operated in parallel and the maximum number of motors that will be in operation. The maximum short-circuit current is calculated assuming a three-phase fault on the load terminals of the protective device. If the system is grounded and the zero sequence impedance is lower than the positive sequence impedance, a line-to-ground fault should be calculated in place of the three-phase fault. The protective device selected should have withstand and interrupting capabilities, including peak current capability, that exceed these calculated. Circuit breakers rated on a symmetrical basis should be applied on the basis of the symmetrical rms fault current. The system power factor at point of application should be greater than the power factor used in establishing the circuit breaker symmetrical rating. If it is not, consideration needs to be given to the circuit breaker's capability to withstand the asymmetrical value.

The asymmetrical rms values of current can be obtained by applying the K1 and K2 factors of Figure 8 to the symmetrical values. The X/R ratio of Figure 8 is determined from the inductive reactance (X) and the resistance (R) of the circuit under consideration.

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Figure 8 —Fault-current decrement conversion factors The short-circuit currents should be determined on the following basis: a)

Maximum asymmetrical rms current: Generator contribution based on circuit impedance, including direct-axis subtransient reactance of generators. Motor contribution based on four times the rated current of induction motors.

b)

Average asymmetrical rms current: Generator contribution based on circuit impedances, including direct-axis subtransient reactance of generators. Motor contribution based on 3.5 times the rated current of motors.

c)

Estimated short-circuit currents: For a preliminary estimate of short-circuit currents, pending the availability of generator reactances, the following may be used for estimating the generator contribution: 1)

Maximum asymmetrical rms current: 10 times generator full-load current.

2)

Average asymmetrical rms current: 8.5 times generator full-load current.

NOTE—These values for estimating generator contribution should not be used where unusually stringent transient voltage sag limitations have been specified for the generator.

d)

Minimum short-circuit current: The minimum available short-circuit current should also be determined to ensure that selectivity and fault clearing will be obtained under these conditions. The 147 Copyright © 2017 IEEE. All rights reserved.

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minimum short-circuit current is based on the least number of generators in operation and no motor load for a phase-to-phase fault at the load end of the cable connected to the protective device on an ungrounded system.

21.3.4 DC systems When calculating the maximum short-circuit current, it should be assumed that each generator that can be simultaneously operated in parallel will, if limited only by internal resistance, contribute 10 times its normal rated current and that all motors that may be in operation simultaneously will, if limited by internal resistance, contribute six times their combined normal ratings.

21.3.5 Fault-current calculations and overcurrent protective devices In addition to the calculation of available short-circuit currents for three-phase faults specified in 21.3.4, calculations should be made of available short-circuit currents for line-to-ground faults on a grounded system. The recommendations of IEEE Std 45.7 should also be considered in regard to the provision of overcurrent protective devices for each ungrounded conductor.

21.3.6 Fixture wires and cords Each lighting branch circuit should be protected by an overcurrent device rated at 20 A or less. Each lighting branch circuit cable should have a continuous current rating equal to or greater than the overcurrent device setting. Fixtures connected to circuits of 15 A or less should have fixture wire or flexible cord of No. 18 AWG (0.82 mm²) or larger. Fixtures connected to 20 A circuits should have fixture wire or flexible cord of No. 14 AWG (2.5 mm²) or larger.

21.3.7 Motor branch circuits For motor branch circuits, overcurrent protection can be provided by fuses or circuit breakers.

The protective devices should be designed to allow current to pass during the normal accelerating period of motors according to the conditions corresponding to normal use. When the time-current characteristics of the overload protective device of a motor are not adequate for the starting period of the motor, the overload protective device may be rendered inoperative during the accelerating period provided that the protection against short circuit remains operative and that the suppression of the overload protection is only temporary.

For continuous-duty motors, protective devices should have time-current characteristics that ensure reliable thermal protection of the motors for overload conditions.

22. System studies, analyses, and reports 22.1 General Details with respect to system studies, analyses, and reports recommended, if applicable, to the design of shipboard electrical power systems are provided in 22.2 through 22.20.

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22.2 Electric plant load analysis (EPLA) Shipboard electrical generating plants must be sized for the anticipated operating load as required by the ship building specification for each class of ships or vessel design. A load analysis is essential to determine the following: 

Quantity and capacity of generators such as ship service generator, emergency generator and propulsion generator for all operating conditions



Capacity of transformers such as ship service, propulsion, etc



Capacity of motor drives, such as propulsion drives



Capacity of UPS and batteries



Capacity of 400 Hz frequency converters (if applicable)



Capacity of shore power connection (or each station in cases of multiple connections)



Margins for detail design, construction, and service life

An electric plant load analysis is a required document that must be approved by an appropriate authority as a part of the overall electrical system design approval. For further details see Annex B, which describes how to conduct an EPLA. Alternatively, the U.S. Navy Design Data Sheet 34 (DDS 310-1 Rev. 1), Electric Power Load Analysis for Surface Ships may be used as a guide to develop a load analysis (refer to IEEE Std 45.3 for details).

22.3 Load flow analysis and voltage drop analysis AC and dc load flow analysis is used to determine component or circuit loading, bus voltage profiles, real and reactive power flow, power system losses, proper transformer tap settings, and voltage drop. The power-flow (or load-flow) analysis is concerned with finding the static operating conditions of an electric power system. Simulating load flow analysis using multiple scenarios helps ensure that the power system is adequately designed to satisfy the desired performance criteria. The load flow analysis is calculated using computer software that provides numerical analysis to simulate actual steady-state power system operating conditions, enabling evaluation of bus voltage profiles, real and reactive power flow, power factor, starting currents, and losses.

The load flow analysis defines the normal steady-state or static operating condition for the optimal power flow, the conditions which give the lowest cost and optimum conditions that satisfy the design constraints while satisfying constraints for power and/or voltage at the network buses. Generally, buses are classified as swing bus, PV 35 (generator) buses, and load buses.

Most utility based power analysis software systems are designed for 50 Hz or 60 Hz ac power systems though some can also analyze dc systems.

Load flow analysis provides the basis for defining a power system. Once the load flow analysis is completed, most software systems can calculate different scenarios for short circuit fault analysis, time based dynamic stability studies (transient and steady-state), protection device coordination, motor starting, arc flash, and harmonic analysis.

The Design Data Sheets are available from the Naval Sea Systems Command, Washington, DC and the Defense Technical Information Center (www.dtic.mil).

35 The “PV”, or “P V” bus, is a voltage controlled bus where generators are connected. The power generation in such buses is controlled through a prime mover, while the terminal voltage is controlled through the generator excitation.

34

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Loads can be modeled as any combination of constant kW, kVA, current, and impedance. The study will take into account tap positions on transformers and indicate where tap changes should be made.

Load flow/voltage drop studies may cover conventional voltage drop analysis, loss analysis, power factor considerations, capacitor placement, long line charging effects, impact loading for motor starting, and cogeneration analysis.

A baseline load flow/voltage drop study should be performed on the first design iteration and any time major changes are made to the power generation and distribution system.

The cognizant design engineer should ensure that the software model for the load flow analysis should receive verification and validation in accordance with program requirements to ensure it is providing the correct results.

22.4 Dynamic analysis (transient and stability) 22.4.1 Background Shipboard or offshore platform electric power systems are non-linear, time varying complex systems that are subject to large signal perturbations. Appropriate stability analysis and design tools must account for this type of system and are typically performed for complex vessels such as navy combatants.

Stability is a quality of a system’s behavior, its dynamic response, associated with an equilibrium and perturbations relative to that equilibrium.

To analyze a real, physical system, first construct a mathematical model of that system. The model, to be useful, must be accurate. Hence, the modeling and simulation approach must be certified as subscribing to a verification, validation, and accreditation plan. This plan establishes the veracity of the model. If the system model does not accurately capture the dynamic response of the power system, then an accurate model must be developed; otherwise, any stability assessment would have no value.

Stability is assessed using the model. If the modeled system indicates stability, this offers confidence that the real, physical system will be stable.

Stability is inextricably tied to equilibria. Equilibria (E) can be continuous functions of initial conditions (ICs), system parameters, and inputs (U being either commanded inputs or exogenous inputs). Upon reaching an equilibrium, a stable system will remain at that point unless perturbed. An equilibrium is a steady-state operating point. A system that possesses no equilibria has no steady state. A system that possesses no equilibria is not usually assessed for stability. Some power systems can have a continuum, or manifold, of equilibria, which can vary continuously as a function of ICs, system parameters, and inputs (U).

Assessing stability is focused on the nature of the power system’s dynamic response when its state vector is not at E. In other words, some perturbation has caused the power system to no longer be in equilibrium.

This perturbation can be due to ICs, a change (time variation) in system parameters, or a change in inputs (U). It is important to understand that stability is assessed relative to the system’s dynamic behavior associated with the post-perturbation equilibrium, which may very well be different from the preperturbation equilibrium. This may help distinguish between what constitutes a small-signal perturbation and a large-signal perturbation.

Ideally, to completely assess the stability of a vessel’s power system, the following actions are required: a)

Identify which form of stability is required for the system.

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b)

Accurately model the system over its entire state space including all possible ICs, system parameters, and inputs (U).

c)

Determine the nature of all equilibria, which may be a manifold (infinite equilibria).

d)

Determine all perturbations about each equilibrium.

e)

For each perturbation about each equilibrium, determine the dynamic response of the system and whether it fulfills the required form of stability.

It should be clear that to do the foregoing is almost certainly infeasible for any reasonably scaled shipboard power system. A tractable, engineered approach is required.

22.4.2 Articulation of working stability criteria Being small signal stable, as established by using frequency domain techniques, and demonstrating bounded behavior, as established by using an associated time domain model and analysis, at selected equilibria, are necessary, but not sufficient, conditions to conclude that the modeled system is stable.

A system is stable if it returns to an acceptable operating point after a disturbance and maintains an acceptable operating point at steady state. For small disturbances, which can be characterized by linear time-invariant dynamics, the system is deemed stable if its eigenvalues are on the left hand complex plane.

This test is equivalent to the Nyquist stability criterion, which states that the locus of the system open loop transfer function, a polar plot, should not encircle the critical point (−1+j0). The open loop transfer function on a dc link is the source-to-load impedance ratio as defined originally by Middlebrook [B9] and later in other references such as Lewis, Cho, Lee, and Carpenter [B8]. The impedance criterion is recommended because it is design oriented and provides guidance to the component designers and system integrators as follows: In the case of one dc source and one dc load, a minimum 6dB of gain margin (20 × log10 (1/OA)) and a minimum 45° of phase margin are recommended. The test is applied at one interface; the load and the source must be independently stable. It is important that the interface at which the test is applied, between source and load, not be crossed by any control signals whose dynamics may contain frequencies of interest; a control loop between the two in the time scale of interest indicates that they are themselves one subsystem and must be considered as such and not as a source and load.

In the case of a distributed dc system, all the components must be independently stable, and all dc interfaces must satisfy condition a) above with the source impedance being the equivalent source impedance and the load impedance being the equivalent load impedance aggregated in the manner recommended by Sudhoff, et al. [B11]. Note that the number of dc interfaces to be tested can be reduced depending on whether they are separated by active or passive components. Here again, components that share information (controls) within the time scales of interest must be considered as one subsystem.

In the case of an ac interface, the general form of the Nyquist criterion can be applied to the source and load QD impedances as recommended by Sudhoff ,et al. [B11].

Bounded behavior, using an associated time domain model and analysis, can be concluded when finite transient recovery times (e.g., 2 s), transients with bounded amplitudes (e.g., 16%−20% max), and an absence of limit cycle behavior is observed. While the apparent amount of “bounding” of a transient response is not necessarily a direct indicator, or measure, of stability, it could indicate good commandfollowing performance. It is a surrogate for a measure that the system is returning to equilibrium. Again, this is considered to be a necessary, but not sufficient, condition for stability.

Operationally speaking, shipboard and offshore platform electric power systems are frequently subject to reconfiguration; in the vernacular, the plant line-ups are changed often. These distinct plant line-ups must 151 Copyright © 2017 IEEE. All rights reserved.

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be modeled accordingly. A pre-reconfiguration equilibrium can be analyzed for small signal stability using frequency domain techniques, which are time invariant techniques. Post-reconfiguration equilibrium can be analyzed for small signal stability using frequency domain techniques. The behavior of the system as it reconfigures can be analyzed using time domain techniques; this analysis would indicate if the postreconfiguration plant line-up arrives within the region of attraction of a post-reconfiguration small signal stable equilibrium.

22.4.3 Recommended dynamic analyses/stability assessments Recommended dynamic analyses/stability assessments are as follows: a)

Being small signal stable (linear stability) at selected equilibria are necessary, but not sufficient, conditions to conclude that the modeled system is stable. A system that is not small signal stable at a selected equilibrium cannot be stable in a more general, nonlinear sense. Using these observations as a basis for a stability criterion leads to tractable approaches for assessing stability.

b)

Develop a model of the system. A time domain model is necessary. A frequency domain model is necessary; the frequency domain model may be derived from the time domain model using established techniques. The veracity of the model must be established within the context of a verification, validation, and accreditation plan.

c)

Determine relevant system equilibria. In the context of a ship or offshore platform, the vessel’s concept of operations will suggest likely steady state operating modes. In addition to likely modes, additional operating points can be selected to provide a “sampling” of ranges of system load levels, “worst case” scenarios, and so on. Selection of equilibria for analysis must also consider perturbed systems. This step is key to ensuring that both time domain and impedance based analyses cover sufficiently and consistently the “total electric power system time domain model” state space. The number of equilibria identified is, by all means, a scope-of-work driver.

Selection of the equilibria must consider that post-perturbation equilibria are most relevant to a stability assessment.

d)

Conduct a frequency domain stability assessment (small signal stability) for each of the selected equilibria. Use the results of this assessment to further define subsequent simulation scenarios, including large signal stability assessments.

e)

Perform the relevant time domain analyses that correspond to the frequency domain analyses of the selected equilibria. Following completion of simulations, review the dynamic response associated with each relevant equilibrium as characterized by the impedance analysis and the simulated time domain behavior. The dynamic response shall be assessed relative to the stability criteria and metrics identified in 22.4.

22.5 Fault current analysis Fault current analysis is used to determine the short circuit current and to study the different failure scenarios that may interfere with the normal system operation. This is done after the one-line diagram is designed and load flow analysis completed using computer based software.

Fault current analysis is used to determine if overcurrent protective devices provide adequate isolation and coordination of protective schemes, and to determine if all electrical equipment has a current interrupting rating equal to or greater than the available fault current.

Most power system analysis software can calculate for both ac and dc fault currents. Both three-phase and single-phase ac power faults have two types of fault currents, symmetrical and asymmetrical. The

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cognizant design engineer should determine the appropriate fault conditions based upon the circuit conditions.

The purpose of fault current analysis is as follows: a)

Determine the adequacy of the power distribution and protection equipment

b)

Decide which equipment is best to use based upon fault studies

c)

Facilitate the proper selection of fuses, relays, and circuit breakers to minimize fault damage

d)

Assess protection coordination and selectivity for the protection system for fault current clearing

e)

Complete analysis of the different fault contributions within multisource power systems

f)

Define the maximum and minimum calculations for fault current, under different scenarios

g)

Help determine the arc flash personal protection equipment for each unique condition

h)

Ensure that the circuit breakers do not exceed their maximum symmetrical and asymmetrical fault currents

i)

Determine if electrical equipment has a sufficient interrupting rating for the available fault current on ac and dc power systems

The fault current analysis should include minimum and maximum source conditions for three-phase, phaseto-phase, and phase-to-ground faults on the transformer primary and secondary systems.

The software model for the fault current analysis should complete verification and validation to provide confidence it is generating correct results.

22.6 Harmonic and frequency analysis It is the cognizant design engineer’s responsibility to be concerned about harmonic distortion issues and interface with the appropriate component vendors to minimize risk, schedule, and cost related to possible damage from harmonics. Harmonic distortion is more prevalent in modern power systems that employ large non-linear (non-sinusoidal) loads (e.g., power electronic power conversion equipment using switching electronics). These non-linear loads produce harmonics that can compromise reliability of the power system. This is because harmonics take energy from the fundamental wave form and distribute that energy into other waveforms that are known as harmonics and sub-harmonics, which cannot be used by the loads.

In doing so, the energy taken from the fundamental waveform is lost. That energy is displaced into other harmonic waveforms, is not used by loads, and adds to heat losses in generation, transmission, transformation, and motors. The resultant (unwanted) harmonic currents are ultimately sourced from the operating power generation equipment. In addition to heating losses, harmonic currents can increase structure-borne vibrations in connected loads and generators and introduce voltage distortion throughout the power system.

Current harmonics in an ac power system generate voltage distortion as they flow through system impedances, which can cause the following: 

Additional heating of power system components



Inductive interference with communication, control systems, and electronics



Over current in capacitors



Generator excitation or AVR control problems



Resonance with power system impedance, which amplifies problems

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

Unwanted mechanical vibrations

On marine applications with generator supplied systems, the higher source impedance can result in much higher levels of voltage distortion when nonlinear loads are present. This is why all marine certifying bodies, including ABS, DNV GL, Lloyds, etc., have mandatory harmonic voltage distortion limits. It is recommended that the design engineer consider the most severe of these standards when addressing harmonics.

Equipment that can cause harmonic distortion includes ac or dc ASDs, soft starters, power supplies, SCRs and solid-state frequency and voltage converters. Power electronics equipment is the source of EMI in electrical power systems. Effect of high harmonics analysis should be based on the highest switching frequency in power electronics equipment. The gate current rise-time in power semiconductors should be limited as much as practical without significant reduction in the power conversion efficiency. The power electronics design should meet EMI requirements of IEC 61000 or MIL-STD-461E-1999.

Sub-harmonics are, by definition, below the fundamental frequency. Although not common in ships, subharmonic resonance can occur due to an incidental relationship of inductive, resistance, and capacitive values in the power system, which can cause oscillation during normal operation or during fault conditions.

Note that spikes and other transient conditions, such as a momentary voltage sag before the generator speed and voltage regulators react and correct the frequency and voltage level, are not considered harmonics or sub-harmonics in this discussion.

The fundamental waveform non-linear distortion, where current draw is dissimilar from the applied voltage, causes harmonics. These harmonics are steady-state (continuous) and therefore are an electrical power quality concern.

Power system harmonic analysis also needs to evaluate “line notching” and possible ringing. Line notching introduces non-characteristic rectifier harmonics and should be addressed during the design process harmonic analysis. Line notching is normally caused by SCRs, thyristors, and diode rectifiers (to a lesser degree) when the line current commutates or transfers from one phase to another. During the commutation period, the two phases are short-circuited because they are electrically connected together for very short time durations through the converter bridge and the ac source impedance. The end result is voltage drops towards the zero crossing as the current increases, limited only by the circuit impedance. Line notching can seriously impact the system power quality, especially when resonance within the power system causes ringing.

The power system design engineer needs to understand that firmware within power electronic power converters sense the input power waveform to rectify the ac power while minimizing line notching. If the source provides three wire isolated power, then the internal sensing for the firmware needs to be from lineto-line with an algorithm to calculate the zero crossing for minimal line notching. If the source provides an isolated or grounded neutral with four wires, then the internal sensing can be from line-to-line with an algorithm to calculate the zero crossing or line-to-ground without an algorithm for minimal line notching.

The degree of power factor (phase control) will affect the magnitude of the harmonics on ac power systems.

Generators use voltage regulators and governors to control voltage and frequency that enable parallel operation. The combination of harmonic distortion and line notching can cause the generators to hunt, resulting in voltage and frequency regulation instability within the control loops of the voltage regulators and governors. This becomes even more severe when generators with excessively high source impedance are specified in order to reduce the power system fault level.

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Harmonic frequencies and the resultant harmonic currents drive heat losses within transformers. These losses include eddy currents, hysteresis, copper losses, and stray flux losses, which can cause failure due to overheating. In addition, winding insulation stress can result when high levels of dv/dt are present.

In extreme cases, there is the possibility of resonance between transformer winding inductance and supply capacitance that cause additional losses. Also, there is the potential for laminated core vibrations that can generate unwanted audible noise. To ensure power system robustness, transformers need to be de-rated, oversized, or harmonic mitigating when supplying nonlinear loads if the current total harmonic distortion (ITHD) is expected to be excessive.

“K-factor” calculations are a common method used when designing and selecting transformers for nonlinear loads. K-factor is a measure of the additional losses that harmonic currents create within the transformer. IEEE and IEC (IEEE Std C57.12.00, IEEE Std C57.12.90, or IEC 60076-1) have standards to de-rate transformers, and it is the responsibility of the cognizant engineer to determine the appropriate standard to use. Selecting a transformer with a K-factor rating no less than the K-factor rating of its load will ensure that the transformer will not overheat due to harmonics. This will, however, have little or no effect in reducing the voltage distortion introduced by the transformer due to the harmonic voltage drops across its impedance. To reduce voltage distortion, harmonic mitigating transformers should be considered.

Similar to a transformer, losses due to harmonics and line notching will increase in rotating equipment.

Additional copper and iron losses (eddy current and hysteresis) will appear in the stator windings, rotor circuit, and rotor laminations. In addition, when fed from PWM ASDs, high dv/dt from the inverter IGBTs can cause winding insulation stress.

Power cable losses also increase with harmonics, which needs to be taken into account when de-rating the cables. Also, over-current protection devices, such as fuses and circuit breakers, must be selected carefully to prevent nuisance tripping or overheating.

The design engineer needs to understand that the actual power factor for the power system reflects the vectoral sum of the fundamental waveform and all of the harmonic waveforms. Non-linear loads, such as rectifier circuits, do not typically shift the current waveform, rather they distort it. These distorted waveforms contain harmonic components that do no useful work and, therefore, are reactive in nature. For nonlinear loads, the power relationship becomes the vector sum of real power (kW), inductive or capacitive reactive power (kVAR), and distortion reactive power (also kVAR) to produce the apparent power that the power system must deliver (kVA). Power factor, by definition, is the ratio of kW to kVA, and for nonlinear loads the kVA includes a harmonic component. True power factor (TPF) becomes the combination of displacement power factor (dPF) and distortion power factor (hPF). Displacement PF is still equal to CosΦ, with Φ being the angle between the fundamental current and voltage. Displacement PF can be either leading or lagging. Distortion PF is then TPF (kW/kVA) divided by the dPF. Distortion PF is neither leading nor lagging. For typical nonlinear loads, the dPF will be near unity. TPF, however, is normally very low because of the distortion component. For example, the dPF of a variable speed drive will be near unity but its total power factor is often in the 0.7 to 0.8 range unless harmonic mitigation equipment is applied.

When the nonlinear loads, such as converters, are small and in low numbers, they will typically not lead to serious harmonic problems. However, when ac to dc converter loads, such as motor drive front ends, become more significant in relation to the power source, say 30% or higher, then special attention should be given to understand the impact on system harmonics and appropriate measures taken to reduce their negative effects.

Harmonic analysis modeling needs to take into account the system impedances and harmonic sources, for each operating mode, to ensure that the total harmonic distortion is within acceptable limits defined in the design requirements. The impact of harmonics on a power system can be modeled using several software packages. The cognizant engineer needs to incorporate the vendor models into the power system design to ensure the most up-to-date data is used.

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If the power system is modeled for sub-harmonics, then the frequency domain should be used to determine stability. Otherwise, the time domain is normally adequate when modeling power systems for harmonics.

For large nonlinear loads or large quantities of smaller nonlinear loads, harmonic mitigation measures should be considered. The most common types are ac or dc reactors, multi-pulse ASDs, tuned passive filters, wide spectrum passive filters, parallel active filters and AFE ASDs. There are many parameters that need to be taken into consideration when analyzing the most suitable harmonic mitigation for a particular application, some of which are as follows:  AC or DC reactors: Reactors are relatively easy to apply and will typically lower the current distortion drawn by the ASD or other nonlinear device by approximately 50% but this is very often not enough to meet acceptable voltage distortion limits. Typical values of reactance used are 3% to 5%. Simply increasing the impedance of the reactor to further reduce current harmonics will have minimal effect and can lead to excessive voltage drops, which will reduce the output power capability of the ASD.  Multipulse ASDs: 12, 18, 24, or higher pulse level ASDs are available with harmonic current reduction increasing with the pulse number. Phase shifting transformers or autotransformers are either built into the ASD or supplied separately. These transformers will add losses reducing the efficiency of the ASD and can significantly increase the space requirements. Also, the effectiveness of the phase shifting in cancelling harmonics is very susceptible to background voltage distortion and voltage imbalance. As little as 2% imbalance can drop the performance to levels no better than a 6-pulse ASD with ac or dc reactor.  Tuned passive filters: Each parallel connected tuned passive filter will target a single harmonic.

Therefore, to address the most predominant harmonics, multiple level filters are required. As a parallel connection, these devices must be reviewed for suitableness whenever new loads are added or the power system is modified. Under lightly loaded conditions, capacitive reactive power can be quite high, so consideration must be given to the ability of the generator’s AVR to handle this capacitive reactance.  Wide spectrum passive filter: These series connected low pass filters are designed to reduce the full spectrum of characteristic harmonics drawn by 6-pulse ASDs. Some filters are capable of reducing current distortion levels to < 5% at full load. Some designs, but not all, introduce high levels of capacitive reactance under lightly loaded conditions, which could lead to generator AVR operational issues. It is important to either select a filter with low capacitive reactive power or include capacitor switching contactors.  Parallel AHF: Parallel connected AHFs are designed to provide the harmonic currents required by the connected nonlinear load. If sized properly, reduction in current harmonic distortion can be quite significant at the targeted harmonics below the 50th provided all 6-pulse ASDs are equipped with an ac reactor (at least 3%) or a dc choke. The AHF accomplishes this by the use of IGBTs, making it similar to the inverter of an ASD. AHFs can inject higher frequency harmonics above the 50th, which can cause problems at much lower distortion levels than the lower frequency harmonics.  AFE ASD: AFE drives reduce input current harmonics with the use of IGBTs to regulate the current drawn by the rectifier. Input current distortion can be substantially reduced at harmonic levels below the 50th. However, as with the AHF, AFE drives also inject higher frequency harmonics above the 50th raising the ITHD levels above 5% when harmonics up to the 100th are taken into consideration. These higher frequencies can cause problems at much lower distortion levels than the lower frequency harmonics. AFE drives can also control power in both directions allowing regeneration of energy when that is a desired function.

In an effort to increase power system reliability, IEEE Std 519 was developed to place stricter limits on harmonics.

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IEEE Std 519 is a shore base standard that can be used for additional design guidance on harmonic control of power systems. Specific attention should be given to instances where parallel AHFs or AFE drives are applied: it is possible that the switching frequencies may generate harmful harmonics well above the typical 2500 Hz to 3000 Hz range. For this reason, when these devices are present all harmonic calculations and measurements should include consideration of the complete harmonic spectrum up to and including the 100th order.

In the event that the design requirements for shipboard power do not specify differently, it is recommended that the voltage harmonic distortion not exceed a VTHD level of 5% with no individual voltage harmonic distortion (IVHD) exceeding 3%.

22.7 Failure mode and effects analysis (FMEA) A failure analysis methodology is used during design to postulate every failure mode and the corresponding effect or consequences. Generally, the analysis is to begin by selecting the lowest level of interest (part, circuit, or module level). The various failure modes that can occur for each item at this level are identified and enumerated. The effect for each failure mode, taken singly and in turn, is to be interpreted as a failure mode for the next higher functional level. Successive interpretations will result in the identification of the effect at the highest function level, or the final consequence. A tabular format is normally used to record the results of such a study. FMEA should be certified and acceptable to the authority having jurisdiction.

The application of variable speed drives is becoming more prevalent on all motor-driven subsystems. The most recognizable of these is still propulsion; however, drives are often employed at lower distribution voltage levels as well. As all drives are inherently producers of harmonic distortion, their potential impact on the harmonic spectrum cannot be ignored. Often, these drives have their own noise mitigation equipment. It is recommended that all drives and all noise mitigation equipment be considered “vital” and be included in any failure mode analysis, regardless of the subsystem where they are applied.

22.8 Electromagnetic interference (EMI) analysis For conducted emissions, EMI analysis requires simulation tools used for harmonic analysis and transient analysis combined and should be performed on complex vessels such as navy combatants. Transient analysis tools are usually capable of capturing the repeated switching events that are essential for EMI analysis, and harmonic analysis is essential for determining spectrum plots. For radiated emission, other tools that are based on finite element analysis and can capture the geometry involved are more suitable.

Guidance for limits is provided by MIL-STD-461 and the IEC 61000 Series.

22.9 Thermal analysis In thermal analysis, a combination of both electrical and mechanical simulation tools is required for complex vessels such as navy combatants. The steady-state results in terms of current, voltage, and power dissipation for both normal and overload conditions are calculated from the electrical simulation tools and then fed into mechanical simulation tools that can model heat exchangers, pipes, flow, pressure, and so forth.

22.10 Electrical power system data for the life-cycle cost analysis Electrical power system data for the total ship life-cycle cost analysis should be prepared as required by the customer.

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22.11 Electrical power system data for the signature analysis Electrical power system data for the total ship signature analysis should be prepared as required by the customer. Signature analysis is conducted as needed to satisfy customer requirements for signatures such as thermal, visual, acoustic, radar, and/or magnetic.

22.12 Safe return to port/survivability analysis A report detailing the electric plant design’s ability to achieve safe return to port (a condition where ship has suffered damage not exceeding the fire casualty threshold as defined by SOLAS), is required for certain passenger ships.

22.13 Future power growth assessment If required by the customer, an assessment of future power growth and the ability of the ship’s electrical power system design to accommodate the projected growth shall be prepared and documented in a report.

22.14 Protective device coordination study System protection of ac and dc power systems deals with the protection from faults through the isolation of faulted parts or circuits from the rest of the network. Power system protection design is undertaken after load flow and fault current analysis has been performed. That is because the full load current and fault current analysis are first required to define system protection requirements. This process is also referred to as protective device coordination (PDC), which employs time current curves using 5-cycle log-log format and a selected one-line diagram that represents the equipment and curves being evaluated. The system protection goal is to isolate fault conditions, and the energy from the fault while maintaining a stable power system, thereby leaving as much of the network as practical in operation. Thus, protection schemes must apply a very realistic and fault finding approach to clear possible future fault conditions. In the past, this was done manually using a light table and thin paper (referred to as onion skins), which could be overlaid.

Today, this is done using computer based software that can quickly reference large libraries of fuses, protection relays, and circuit breakers. Many standards are available for establishing system protection and it is up to the cognizant design engineer to use the appropriate standard(s).

The one-line drawing that was generated for load flow and fault current analysis is then drawn up into segments that display each protection zone. Each zone needs to be overlapping to ensure that all parts of the power system are protected. Typically, the system is selective such that the protective device closest to the fault will trip before the devices at the power source. This design helps to ensure continuity of ship’s electric power during a fault in the distribution system. Protective device time-current curves for each zone should be analyzed to ensure selectivity. Where selectivity is not achieved, protective devices must be adjusted or changed, or a small level of non-selectivity must be accepted.

System protection may be implemented using the following components:  Current and voltage transformers for sensing  Protective relays that are microprocessor based  Circuit breakers to open/close circuits within the system based on relay and auto-recloser commands  Fuses capable of both sensing and disconnecting faults

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 UPS and batteries to provide back-up power in case of power disconnection in the system  Communication systems for remote control and alarms It is the responsibility of the power system design engineer to assess the different types of electrical equipment and the required different types of protection so as to define each unique protection scheme.

Common types of power equipment requiring fault protection are generators, motors, loads, transmission systems, transformers, and low voltage networks. Each type of load requires its own customized system protection that is documented on a time current curve in accordance with the applicable standards, manufacturer’s guidelines, and program requirements.

22.15 Grounding system design report If required by the customer, the design of the grounding system should be documented in a grounding system design report.

22.16 Electrical power system corrosion control report If required by the customer, potential stray current sources, other electrical power system-related causes of corrosion, and the corrosion control measures incorporated in the design should be documented in an electrical power system corrosion control report.

22.17 Electrical power system input to ship’s weight report If required by the customer, data for the electrical power system equipment section of the ship’s weight report should be prepared.

22.18 Electrical power system section of the master equipment list If required by the customer, data for the electrical power system section of the total ship master equipment list should be prepared.

22.19 Electrical power system input to endurance fuel calculations If required by the customer, data required for calculating fuel consumption for the purpose of sizing fuel tanks shall be prepared. Commercial ships are required to comply with MARPOL requirements, including calculation of the Energy Efficiency Design Index (EEDI) adopted by IMO on April 14, 2014 (Resolution MEPC.245(66) [B10]).

22.20 Incident energy analysis An incident energy analysis should be provided to document the available arc-flash incident energy at all locations in the system where the short-circuit current is calculated.

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23. EMI/EMC/RFI The power system and user loads should be designed and/or selected to ensure EMC. The specifications for the power system and loads should limit EMI and RFI. Applicable standards include MIL-STD-461, IEC 61000 series, and IEEE Std C63.12.

24. Materials 24.1 Corrosion-resistant parts Where essential to minimize deterioration due to marine atmospheric corrosion, corrosion-resisting materials, or other materials treated in a satisfactory manner to render them adequately resistant to corrosion, should be used. Silver, corrosion-resisting steel, copper, brass, bronze, copper-nickel, certain nickel-copper alloys, and certain aluminum alloys are considered satisfactory corrosion-resisting materials.

Special care should be used to not allow parts of different materials to come into contact with each other. If this happens a typical dissimilar metals corrosion cell can be formed, damaging the parts.

The following treatments, when properly performed and of a sufficiently heavy coating, are considered satisfactory corrosion-resistant treatments: 

Electroplating: This provides only minimal protection. Other suitable additional coating systems should be used to protect electroplated parts if they are exposed to a salt or corrosive atmosphere.



Sherardizing: This will not work when continuously exposed to salt air, salt waters, and agricultural and industrial pollution. The parts must be over coated with an additional proper protective system.



Galvanizing: This will not work when continuously exposed to salt air, salt water, and agricultural and industrial pollution. The parts must be over coated with an additional proper protective system.



Dipping and painting (phosphate or suitable cleaning, followed by the application of a coating system meeting the requirements of ASTM B117-97, applicable NACE & Coating Society Standards).

These provisions apply to the following components: 

Parts: Interior small parts that are normally expected to be removed in service, such as bolts, nuts, pins, screws, cap screws, terminals, brush holder studs, springs, and so on.



Assemblies, subassemblies, and other units where necessary due to the unit function, or for interior protection, such as shafts within a motor or generator enclosure, and surface of stator and rotor.



Enclosures and their fastenings and fittings: Enclosing cases for control apparatus, outer cases for signal and communication systems (both outside and inside), and similar items, together with all their fastenings and fittings that would be seriously damaged or rendered ineffective by corrosion.

24.2 Flame-retardant materials Flame-retardant materials and structures should be used to the maximum extent practicable throughout the vessel. These materials should have such fire-resisting properties that they will not convey flame nor continue to burn for longer times than specified in the appropriate flame test.

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materials and structures being considered, unless specific applicable tests are invoked in these recommendations.

24.3 Brittle material Porcelain or other brittle insulating materials should not be used for bus supports, lamp sockets, receptacles, fuse blocks, and so on, where the material is rigidly fastened by machine screws or equivalent.

24.4 Cable selection, application, and installation Cables are ubiquitous throughout a ship’s electrical power generation and distribution system, providing both the interconnection to move power throughout the ship, but also provide the control signals. IEEE Std 45.8 provides recommendations for selection, application, and installation of electrical power, signal, control, data, and specialty marine cable systems.

25. Power system grounding (earthing) 25.1 General The design baseline should establish the type of grounding for various parts of the ship’s power system.

The baseline design of shipboard power system grounding should generally follow the guidance of IEEE Std 142 and, for power electronic equipment specifically, IEEE Std 1100. All definitions from those references apply. While those two references are comprehensive with respect to terrestrial/industrial power systems, this clause focuses on specific, additional aspects regarding shipboard systems.

25.2 Power system grounding The major challenge in shipboard power system grounding is to strike a balance between maximizing the QoS to the loads, minimizing hull current flow, and minimizing damage from arc faults and transient overvoltage, while ensuring safety of personnel.

No one simple answer exists to the problem of grounding. Each of a number of possible solutions to a grounding problem has at least one feature that is outstanding, but which is obtained at some sacrifice of other features that may be equally worthy. Thus, the selection of the class and means of grounding is often a compromise between somewhat conflicting solutions.

From all of the various grounding methods described in IEEE Std 142, the following three are relevant for shipboard systems: 

High-resistance grounded



Solidly grounded



Ungrounded

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Four major classes of circuits can be distinguished for which different grounding methods may be applied.

While any of the three relevant grounding methods may be used for each of the classes of circuits, the following methods are recommended: 

Medium voltage primary buses should be high-resistance grounded.



Primary low voltage buses and distribution buses should be either high-resistance grounded or ungrounded.



Secondary low voltage buses should be solidly grounded.



Special circuits such as hospital outlets may require special grounding treatment.

In practice, combinations of up to all three grounding methods may coexist in separately derived systems.

Per definition, separately derived systems demonstrate galvanic isolation between them.

Figure 9 illustrates the recommended grounding scheme for an integrated shipboard power system (50 Hz or 60 Hz ac or dc). As indicated in Figure 9, it is important to provide the required grounding means at each separately derived system (see definition in IEEE Std 142).

High-resistance grounded and ungrounded systems should provide a means for detecting and locating ground faults (see ground detector indicator (GDI) in Figure 9).

H R

H R

H R

H R

G

G

G

G

Other Primary Loads

Primary Bus

G

G: Motor M: Generator

H R

High Resistance Ground

VFD

Variable Frequency Drive

GDI

Ground Detector Indicator Legend

VFD

VFD

M

M

GDI

H R

Distribution Bus

Distribution Loads

Other Distribution Loads M

GDI

Other Secondary LV Loads

Secondary LV Bus Secondary LV Loads

Figure 9 —System grounding

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25.3 Point of system grounding System grounding should be accomplished at the transformer wye secondary or generator neutral. If a transformer wye secondary is unavailable in an ac system, grounding transformers should be used.

If separately derived systems can be merged into one (e.g., by means of reconfiguration via circuit switches), the system designer must ensure that the combined system again fulfills the necessary requirements for the desired grounding method.

Special attention should be paid to grounding solutions that can introduce corrosion damage to other components of the ship, especially to structural components that are made of stray-current-sensitive materials such as aluminum, stainless steel, carbon fiber, high-performance steel, galvanized steel, and coating systems. Grounding systems should not allow surface leakage at connection or interface points that can lead to the failures of the grounding systems or their attachment points.

25.4 Equipment grounding 25.4.1 General Equipment grounding should follow the guidelines established in IEEE Std 142 or IEEE Std 3003.2.

Requirements for equipment grounding are found in article 250, chapter VI, of the National Electrical Code® (NEC®) (NFPA 70) or other appropriate standard.

The design and physical arrangement of equipment should be closely examined for potential current leakage problems that could create stray electrical currents. These can include, but are not limited to, wet surface short circuits across isolation insulators, antenna connection points, metal electrical equipment containment cabinets, and interface points.

Exposed non-current-carrying metal parts of fixed equipment that may become energized because of any condition for which the arrangement and method of installation does not ensure positive grounding should be permanently grounded through separate conductors or grounding straps, securely attached, and protected against damage.

The metal case of each instrument, relay, meter, and instrument transformer should be grounded.

Instrument and control transformer enclosures should be grounded to the ship structure.

Each receptacle outlet that operates at 55 V or more should have a grounding pole. However, this requirement does not apply to lamp bases, shades, reflectors, or guards supported on lamp holders or lighting fittings constructed of or shrouded in non-conducting material. Grounding poles are also not required on portable appliances that have double insulation, or portable appliances that are protected by isolating transformers. Grounding poles are not required on bearing housings that are insulated in order to prevent the circulation of current in the bearings. Grounding poles are not required on apparatus supplied at not more than 55 V. 25.4.2 Equipment grounding methods All non-current-carrying metallic parts of electrical equipment should be effectively grounded by the following methods. Metal frames or enclosures of apparatus should be fixed to, and be in metallic contact with, the ship's structure, provided that the surfaces in contact are clean and free from rust, scale, or paint when installed and are firmly bolted together. Alternatively, they should be connected to the hull either

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directly by ground strap or, for portable equipment, via the grounding terminal of a receptacle outlet. A reading of 0.1 Ω (dc resistance) or less should be achieved between an equipment enclosure and an adjacent structural ground potential point.

Metallic cable sheaths or armor should not be solely relied on for achieving equipment grounding. The metallic sheaths and armor should be grounded by means of connectors or cable glands approved, listed, or labeled for the purpose and designed to ensure an effective ground connection. The stuffing tube should be firmly attached to, and be in effective electrical contact with, a grounded metal structure. Conduits should be grounded by being screwed into a grounded metallic enclosure, or by nuts on both sides of the wall of a grounded metallic enclosure where contact surfaces are clean and free from rust, scale, or paint.

As an alternative to the methods described in the above paragraph, armor and conduit may be grounded by means of clamps or clips of corrosion-resistant metal, making effective contact with the sheath or armor and grounded metal. All joints in metallic conduits and ducts and in metallic sheaths of cables that are used for ground continuity should be solidly made and protected against corrosion.

Every grounding conductor should be of copper or other corrosion-resistant material and should be securely installed and, where necessary, protected against damage and electrolytic corrosion.

On wood and composite ships, a continuous-ground conductor should be installed to facilitate the grounding of non-current-carrying exposed metal parts. The ground conductor should terminate at a copper plate of area not less than 0.2 m² fixed to the keel below the light waterline in a location that is fully immersed under all conditions of heel.

Every ground connection to the ship structure, or on wood and composite ships to the continuous ground conductor, should be made in an accessible position and should be secured by a screw or connector of brass or other corrosion-resistant material used solely for that purpose.

All armor or other metal coverings of cable should be electrically continuous throughout the entire length and should be effectively grounded to the hull of the ship at both ends, except for branch circuits (final subcircuits), which may be grounded at the supply end only. The metallic braid or sheath should be terminated at the stuffing tube or connector where the cable enters the enclosure and should be in good electrical contact with the enclosure.

Methods of securing aluminum superstructures to the steel hull of a ship often include insulation to prevent galvanic corrosion between these materials. In such cases, a separate bonding connection should be provided between the superstructure and the hull. The connection should be made in a manner that minimizes galvanic corrosion and permits periodic inspection.

25.4.3 Grounding of portable equipment Portable electrical equipment energized from the ship's electrical system should have all exposed metal parts grounded. This should be accomplished by an additional conductor (green) in the portable cable and a grounding device in the attachment plug and receptacle. Further safety can be provided by the use of an isolating transformer. Double-insulated portable electrical equipment need not have exposed metal parts grounded.

25.5 Ground plates on nonmetallic ships On nonmetallic hull ships, ground plate(s) installed to provide an earth ground connection via contact with sea water should be installed to establish ground potential. The ground plate(s) should be installed at the lowest point of the structural hull, as close as possible to the vertical of the mast in a location that is fully immersed under all conditions of heel. Each ground plate should be a copper plate of area not less than 164 Copyright © 2017 IEEE. All rights reserved.

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0.2 m2. A through bolt should be brazed to each ground plate to provide a connection point for installation of the cable grounding system ground plane. When the ship is removed from the water, an appropriate ground should be established and maintained.

25.6 Lightning protection grounding Lightning protection should follow the guidelines given in NFPA 780 (chapter 10, “Protection for Watercraft”), or other appropriate standard.

Lightning protection should be provided for each mast on wooden and composite vessels, and for each wooden or composite mast on steel vessels. Where the height of an antenna exceeds that of the mast, and the antenna is equipped with lightning protective devices, separate mast lightning protection need not be provided.

Lightning protection on wooden and composite vessels should consist of continuous tape or wire having a section of not less than 100 mm² (4/0 AWG 212 000 cmil) attached by copper rivets or clamps to a copper spike not less than 13 mm in diameter, projecting at least 150 mm above the top of the mast. The copper tape or wire should be run to a copper plate having an area not less than 0.2 m², fixed to the keel below the light water line in a location that is fully immersed under all conditions of heel. No grounding conductor should be attached to the lightning conductor plate. The copper plate should be separate from and in addition to the copper plate for terminating the grounding conductor.

25.7 Stray current protection The ship design should prevent or control corrosion caused by stray electrical currents entering through the hull from the sea. In particular, the ship design should account for stray electrical currents while in port due to the grounding systems of the shore power system and other ships.

NOTE—Electrical currents created by any type of electrical source equipment will produce return currents to that source through the grounding systems. Therefore, sizing the grounding conductors, buses, systems, lugs, connectors, etc. between equipment and ground systems must take into account these return path currents. Otherwise, stray electrical currents will travel through unwanted areas of the ship, including hulls, decks, railings, and any materials, tools or devices that are in contact with these return paths. Corrosion will occur when this happens, particularly at wet access zones. Electrical currents can build up at improper ground points, causing unpredictable discharge voltages to appear. Personnel safety can be jeopardized if these currents come into contact with the crew, equipment, or tools that the crew may be working with on the ship.

25.8 Ground-fault detection 25.8.1 General Means to continuously monitor and indicate the state of the insulation-to-ground should be provided for electric propulsion systems and integrated electric plants; ship service and emergency power systems; lighting systems; and power or lighting distribution systems that are isolated from the ship service or emergency power and lighting system by transformers, motor-generators, or other devices.

For insulated (ungrounded) distribution systems, a device or devices should be installed that continuously monitor and display the insulation level and give audible and visual alarms in case of abnormal conditions.

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When a ship is designed for operation with an unattended machinery space, ground detection alarms should be connected to the machinery control monitoring and alarm system.

Ground indicators should be located at the ship service switchboard for the normal power, normal lighting, and emergency lighting systems; at the emergency switchboard for emergency power and lighting; and at the main power switchboard for integrated propulsion systems. All ground indicators should be readily accessible.

25.8.2 Ground detection on ungrounded systems Ground detection for each ungrounded system should have a monitoring and display system that has a lamp for each phase that is connected between the phase and the ground. This lamp should operate at more than 5 W and less than 24 W when at one-half voltage in the absence of a ground. The monitoring and display system should also have a normally closed, spring return-to-normal switch between the lamps and the ground connection. If lamps and continuous ground monitoring utilizing superimposed dc voltage are installed, the test switch should give priority to continuous ground monitoring and should be utilized only to determine which phase has the ground fault by switching the lamps in. With continuous ground monitoring tied into the alarm and monitoring system, consideration will be given to alternative individual indication of phase to ground fault. If lamps with a low impedance are utilized, the continuous ground monitoring is reading ground fault equivalent to the impedance of the lamps, which are directly connected to the ground.

Where continuous ground monitoring systems are utilized on systems where nonlinear loads (e.g., ASDs) are present, the ground monitoring system must be able to function properly.

25.8.3 Ground detection on grounded neutral ac systems Ground detection for each ac system that has a grounded neutral should have an ammeter and ammeter switch that can withstand the maximum available fault current without damage. The ammeter should indicate the current in the ground connection and should have a scale that accurately, and with clear definition, indicates current in the 0 A to 10 A range. The ammeter switch should be the spring return-to-on type.

The ammeter and current transformer should both be of such a design that they are not damaged by ground fault currents. Where the ammeter is located in a remote enclosure from the current transformer, a suitable protective device should be provided to prevent high voltage in the event of an open circuit. A shortcircuiting switch should be connected in parallel with the protective device for manually short-circuiting the remote part of the current transformer.

For high resistance grounded systems, an indicating ammeter or voltmeter should be provided to indicate ground current flow.

26. Arc flash management Shipboard electrical systems requirements have changed due to proliferation of electric propulsion and electric drive auxiliaries. The shipboard power generation and distribution requirements are being challenged due to limited space in the ship, as well as dynamic behavior of the ship in motion, and due to salt water contact of the hull, as well as moisture in the atmosphere. Many shipboard electrical accidents are attributed to electrical arc flash situations, starting with phase to ground and then phase to phase short circuits, often leading to a bolted fault. Shipboard electrical system arc flash detection and management strategies have become urgent needs for the overall safety of the ship.

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For industrial power systems, the arc flash requirements are in OSHA 29 Code of Federal Regulations (CFR) Part 1910 Subpart S; NFPA 70, National Electrical Code; NFPA 70E, Standard for Electrical Safety in the Workplace; and IEEE Std 1584, IEEE Guide for Performing Arc-Flash Hazard Calculations. These documents are often used as guidance for arc flash management aboard ships.

Due to the nature of an arc flash occurrence and due to the fact that arcing can cause a devastating blast, the best and most efficient way to mitigate arc flash incident energy onboard ship is to detect and clear the arcing fault as fast as possible. The ways to detect an arcing fault, and clear it to prevent injury, are as follows: 

Simply modifying the existing settings of protective devices.



Apply new technologies that have been developed to detect the arcing fault instantly during an arc flash incident.



Taking advantage of alternative protection schemes, such as differential protection and zone interlocking, because these types of schemes detect the fault instantaneously. Some of these actions are recommended for the new designs and some are recommended for existing systems.

NOTE—These technologies should be considered in order to detect an arcing fault as quickly as possible. However, these devices only sense the arcing fault and send a signal to the circuit breaker to trip. The circuit breaker is an electromechanical device and must be properly maintained to help ensure that it will open and clear the fault as quickly as possible.

This section is dedicated to shipboard arc flash requirements, which is derived from regulations and recommendations, as noted above.

Shipboard power system fault current analysis is done using many different methods such as USCG guide, IEEE guide, NAVSEA design data, IEC, and combination of engineering software. Some of those are presented to provide users with the many choices of applications. However, it is recommended that an arc flash study be performed for each ship.

The following recommendations are to minimize potential of an arc flash in electrical equipment onboard a ship: a)

New design 1)

Develop redundant equipment for essential systems so that operation can be transferred to the stand-by system. This will allow complete shutdown of the equipment, power off the system, and troubleshoot or perform maintenance following every safety measure.

2)

Detail and maintain complete and correct electrical one line diagrams that include short circuit current, overcurrent protective device coordination, and the results of the arc flash analysis.

3)

Make an attempt to better coordinate the protective devices so that arcing detection time is minimized, which can reduce arc flash incident energy. This can function very well with properly modeling the system coordination.

4)

Develop a better understanding of the relation between fault current analysis and arc flash analysis so that the protective device settings are well managed and set/reset for arc flash testing. This can greatly reduce arc flash and explosion.

5)

Periodic thermography will provide a health check of all connection points. One of the reasons of arcing is a loose electrical connection.

6)

Integrate arc detection and protection for equipment such as switchgear and motor control centers. There are proven systems that work very well. Again, this is only detection, not clearing.

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7)

Manage the harmonics at the system level during design phase so that electrical noise-related arcing is minimized to meet regulations. This is better done by system level modeling and simulation.

8)

Manage system level transient so that the system is stabilized to meet regulations. This is better done by system level modeling and simulation.

9)

Install appropriate arc flash warning label plates as required by the ship owner.

10) Instill ship level certifications for arc flash compliance with periodic review by the ship engineers.

11) Train the operators properly to understand the arc flash related safety measures and train/retrain the operators periodically as required by the owner.

NOTE—Maintenance of all overcurrent protective devices per the manufacturer’s instructions, especially circuit breakers, is vital to helping ensure that these devices will open and clear the fault as rapidly as possible. All of the above options strictly depend on intended application of the vessel.

Electric propulsion with DP system should be given priority of arc flash management measures.

b)

Retrofit 1)

Detail and maintain complete and correct electrical one line diagrams that include short circuit current, overcurrent protective device coordination, and the results of the arc flash analysis.

2)

Make an attempt to better coordinate the protective devices so that arcing detection time is minimized, which can reduce arc flash incident energy. This can function very well with properly modeling the system coordination.

3)

Develop a better understanding of the relation between fault current analysis and arc flash analysis so that the protective device settings are well managed and set/reset for arc flash testing. This can greatly reduce arc flash and explosion.

4)

Integrate arc detection and protection for equipment such as switchgear and motor control centers. There are proven systems that work very well. Again, this is only detection, not clearing.

5)

Manage the harmonics at the system level during design phase so that electrical noise-related arcing is minimized to meet regulations. This is better done by system level modeling and simulation.

6)

Manage system level transient so that the system is stabilized to meet regulations. This is better done by system level modeling and simulation.

7)

Install appropriate arc flash warning label plates as required by the ship owner

8)

Instill ship level certifications for arc flash compliance with periodic review by the ship engineers

9)

Train the operators properly to understand the arc flash related safety measures and train/retrain the operators periodically as required by the owner.

10) Maintenance of all overcurrent protective devices per the manufacturer’s instructions, especially circuit breakers, is vital to helping ensure that these devices will open and clear the fault as rapidly as possible.

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27. Hazardous locations, installations, and equipment 27.1 General Hazardous (classified) locations are those locations (areas) where fire or explosion hazards may exist due to the presence of flammable gases, flammable liquid-produced vapors, combustible liquid-produced vapors, combustible dusts, or fibers/flyings. Electrical equipment and wiring should not be installed in such locations unless essential for operational purposes. When reference is made to installed electrical equipment and wiring, such reference applies to fixed or stationary electrical equipment and wiring. When electrical equipment is installed in these locations, special precautions should be taken to ensure that the electrical equipment is not a source of ignition. All electrical equipment installed in hazardous locations should be suitable for the specific classification of the space or area in which it is installed.

NOTE—The following equipment, while not addressed by this section, could also potentially become an ignition source in hazardous (classified) locations:  Portable or transportable electrical equipment having self-contained power supplies, such as battery-operated equipment  Non-electrical equipment such as pumps, gearboxes, brakes, hydraulic and pneumatic motors and fans involving potential ignition sources such as hot surfaces and mechanically generated (percussive) sparks  Equipment utilizing optical emissions technology, such as laser equipment

Classification of spaces adjacent to hazardous locations is dependent on many factors such as access doors, opening, and ventilation. In general, fitting adjacent spaces with an airtight door is sufficient to downgrade the hazardous area by one division or zone (e.g., from Division 1 to Division 2) if an appropriate ventilation scheme is provided. Section 12.5 of API RP 500-2012 or API RP 505-1997, as applicable, provides guidance on the classification of adjacent spaces.

27.2 Hazardous area classification 27.2.1 Overview The National Electrical Code (NEC) classifies hazardous locations in Articles 500 through 504 for the NEC Division classification system, and in Articles 505 and 506 for the NEC Zone classification system.

Similarly, the Canadian Electrical Code (CEC) classifies hazardous locations in Appendix J for the CEC Division classification system, and in Section 18 for the CEC Zone classification system.

In addition to the area classification details in 27.2, reference the NEC/CEC for further information. 36

36 The referenced NEC and CEC Zone classification systems above are based on the IEC Zone classification system. The IEC consists of the National Committees from over 80 participating countries, and cooperates in international standardization with organizations like the International Organization for Standardization (ISO) and the IEEE. The IEC has developed standards for hazardous locations that have been adopted in many countries with national or regional differences. While both the NEC and CEC have adopted the Zone classification system in addition to their traditional Division classification systems, the supporting NEC/CEC Zone standards and requirements are not identical to the comparable IEC Zone standards and requirements due to the need for national differences. The need for US and Canadian national differences is primarily driven by differences involving installation requirements. IEC-harmonized Zone standards and requirements for equipment, for area classification, and for installation have been published in North America, or are in the process of being published, with all involving national differences. Examples of such standards published by SDOs such as API, CSA, IEEE, ISA, NFPA and UL include ANSI/API RP 505, CAN/CSA C22.2 No. 60079-0, IEC/IEEE 60079-30-1, ANSI/ISA/UL 60079-0, ISA TR12.24.01, and ANSI/NFPA 70.

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27.2.2 NEC and CEC division classification systems 27.2.2.1 Types of explosive atmosphere The NEC/CEC Division classification systems use three classes to define the types of explosive atmosphere, as follows:  Class I: Flammable gases, flammable liquid-produced vapors, and combustible liquid-produced vapors  Class II: Combustible dusts  Class III: Ignitible fibers/flyings Examples of where flammable gases or flammable/combustible liquid-produced vapors may exist include battery rooms, paint lockers, pump rooms, cargo tanks, and weather deck locations above cargo tanks on tank vessels. Examples of where combustible dusts may exist include the interior of coal bins and cargo holds in vessels carrying coal.

NOTE—Local and regional codes and regulations may involve differences to the classification system requirements detailed in this standard. Some examples of such include Zone 10 or Z, or Zone 11 or Y, as referenced in the U.S. Code of Federal Regulations (CFR), Title 46: Shipping, Chapter I: Coast Guard, Department Of Homeland Security, Subchapter J: Electrical Engineering, Subpart 111.105: Hazardous Locations.

27.2.2.2 Likelihood that the explosive atmosphere is present The NEC/CEC Division classification systems use two divisions, based on the hazard probabilities during normal and abnormal operations: Class I  Division 1: Where ignitible concentrations of flammable gases, flammable liquid-produced vapors, and combustible liquid-produced vapors can exist all of the time or some of the time under normal operating conditions, or frequently because of repair, maintenance, or leakage.  Division 2: Where ignitible concentrations of flammable gases, flammable liquid-produced vapors, and combustible liquid-produced vapors are not likely to exist under normal operating conditions, or adjacent to a Class I, Division 1 location from which such ignitible concentrations might occasionally be communicated.

Class II  Division 1: Where ignitible concentrations of combustible dusts can exist all of the time or some of the time under normal operating conditions, or frequently because of repair, maintenance, or leakage.  Division 2: Where ignitible concentrations of combustible dusts are not likely to exist under normal operating conditions, or adjacent to a Class II, Division 1 location from which such ignitible concentrations might occasionally be communicated.

Class III  Division 1: Where easily ignitible fibers or materials producing combustible flyings are handled, manufactured, or used.  Division 2: Where easily ignitible fibers are stored or handled.

Although not defined by the NEC/CEC, there can be a need for further defining an area of specific increased hazard due to a higher likelihood of the presence of ignitible concentrations of flammable gases or vapors. API RP 500 refers to these areas as “Special Division 1 locations,” which is similar in 170 Copyright © 2017 IEEE. All rights reserved.

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application as Class I, Zone 0 locations. See 27.2.3 below for additional details on Class I, Zone 0 locations.

27.2.2.3 Ignition-related properties of the explosive atmosphere The NEC/CEC identify Class I, Division “Groups” based on the characteristics of the gas or vapor that may be present, including the maximum experimental safe gap (MESG) or the minimum igniting current ratio (MIC ratio) of the particular gas or vapor, as defined by NFPA 497. In the NEC/CEC Division classification systems, flammable gases, flammable liquid-produced vapors, and combustible liquidproduced vapors are grouped as follows:  Group A: The only gas included in Group A is acetylene.  Group B: The MESG is less than or equal to 0.45 mm, or the MIC ratio is less than or equal to 0.40.

Hydrogen is a typical Group B material.  Group C: The MESG is greater than 0.45 mm and less than or equal to 0.75 mm, or the MIC ratio is greater than 0.40 and less than or equal to 0.80. Ethylene is a typical Group C material.  Group D: The MESG is greater than 0.75 mm, or the MIC ratio is greater than 0.80. Propane is a typical Group D material.

Regarding Class II combustible dusts, the NEC/CEC Division classification systems group them as follows:  Group E: Atmospheres containing combustible metal dusts. Aluminum and magnesium are typical Group E materials.  Group F: Atmospheres containing combustible carbonaceous dusts that have more than 8% total entrapped volatiles, or that have been sensitized by other materials so that they present an explosion hazard. Coal, carbon black, charcoal, and coke dusts are typical Group F materials.  Group G: Atmospheres containing combustible dusts not included in Group E or Group F. Flour, grain, wood, and plastic are typical Group G materials.

Regarding Class III ignitible fibers/flyings, there are no groupings under the NEC/CEC Division classification systems.

27.2.2.4 Maximum surface temperature of equipment The maximum surface temperature of equipment involves a temperature classification that is indicated either as a specific maximum temperature value (e.g., T135 °C) or as a specific temperature code (T-Code) value (e.g., T4). This temperature classification is related to the ignition-related properties of the explosive atmosphere, such as the auto-ignition temperature for explosive gases, or such as the layer or cloud ignition temperature for explosive dusts.

The NEC/CEC Division classification systems define the specific Class I and II T-Code options are shown in Table 25: Table 25 —Class I and II division temperature classifications T1 T2 T2A T2B

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T2C T2D T3 T3A T3B T3C T4 T4A T5 T6

(≤230 °C) (≤215 °C) (≤200 °C) (≤180 °C) (≤165 °C) (≤160 °C) (≤135 °C) (≤120 °C) (≤100 °C) (≤85° C)

For Class III, the above T-Code options do not apply. Class III equipment is limited to 165 °C for equipment not subject to overloading, and limited to 120 °C for equipment that may be overloaded.

27.2.3 NEC and CEC zone classification systems 27.2.3.1 Types of explosive atmosphere Regarding areas involving flammable gases and flammable/combustible liquid-produced vapors, the NEC Zone classification system uses “Class I” to define the hazard, just like for the NEC/CEC Division classification systems. However, the CEC Zone classification system does not use the term “Class I”. This is because the CEC Zone classification system relies upon the “Zone” designation to indicate both the type of explosive atmosphere and the likelihood that the atmosphere is present.

For areas involving either combustible dusts or ignitible fibers/flyings, neither the NEC nor CEC use the terms “Class II” or “Class III”. The “Class” terminology is not used because the NEC/CEC Zone classification systems rely upon the “Zone” designation to indicate both the type of explosive atmosphere and the likelihood that the atmosphere is present.

27.2.3.2 Likelihood that the explosive atmosphere is present The NEC/CEC Zone classification systems use the following three zones to represent the likelihood of the flammable gases and flammable/combustible liquid-produced vapors being present, based on the hazard probabilities during normal and abnormal operations: 

Zone 0: Where ignitible concentrations of flammable gases, flammable liquid-produced vapors, and combustible liquid-produced vapors are present continuously or for long periods of time under normal operating conditions. (An example of Zone 0 is the air space in an atmospheric tank containing a flammable liquid.)



Zone 1: Where ignitible concentrations of flammable gases, flammable liquid-produced vapors, and combustible liquid-produced vapors are likely to exist under normal operating conditions, or frequently because of repair, maintenance, or leakage.



Zone 2: Where ignitible concentrations of flammable gases, flammable liquid-produced vapors, and combustible liquid-produced vapors are not likely to exist under normal operating conditions, or adjacent to a Class I, Zone 1 location from which such ignitible concentrations might occasionally be communicated.

For combustible dusts and ignitible fibers/flyings, the NEC/CEC Zone classification systems use the following three zones:

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 Zone 20: Where ignitible concentrations of combustible dusts and ignitible fibers/flyings are present continuously or for long periods of time under normal operating conditions. (Examples of Zone 20 locations include locations inside of dust containment systems.)  Zone 21: Where ignitible concentrations of combustible dusts and ignitible fibers/flyings are likely to exist under normal operating conditions, or frequently because of repair, maintenance, or leakage. (Examples of Zone 21 locations include locations outside dust containment and in the immediate vicinity of access doors.)  Zone 22: Where ignitible concentrations of combustible dusts and ignitible fibers/flyings are not likely to exist under normal operating conditions, or adjacent to a Class I, Zone 1 location from which such ignitible concentrations might occasionally be communicated. (Examples of Zone 22 locations include outlets from bag filter vents.)

27.2.3.3 Ignition-related properties of the explosive atmosphere The NEC/CEC identify “Gas Groups” for Zones 0, 1, and 2 based on the characteristics of the gas or vapor that may be present, including the MESG or the MIC ratio of the particular gas or vapor, as defined by NFPA 497. In the NEC/CEC Division classification systems, flammable gases, flammable liquid-produced vapors, and combustible liquid-produced vapors are grouped as follows:  Group IIC: The MESG is less than or equal to 0.50 mm, or the MIC ratio is less than or equal to 0.45. Acetylene and hydrogen are typical Group IIC materials. Group IIC is considered equivalent to a combination of Class I, Groups A and B.  Group IIB: The MESG is greater than 0.50 mm and less than or equal to 0.90 mm, or the MIC ratio is greater than 0.45 and less than or equal to 0.80. Ethylene is a typical Group IIB material. Group IIB is considered equivalent to Class I, Group C.  Group IIA: The MESG is greater than 0.90 mm, or the MIC ratio is greater than 0.80. Propane is a typical Group IIA material. Group IIA is considered equivalent to Class I, Group D. NOTE—Both acetylene and hydrogen are in the same group in the Zone system, as opposed to different groups in the Division system. A common marking convention to represent just the hydrogen portion of Group IIC is “IIB+H2”.

While IIB + H2 is not a “group” per se, certain electrical equipment is tested for such gases as a convenience to the user and the manufacturer if the equipment must be suitable for hydrogen but not acetylene atmospheres.

Regarding combustible dusts and ignitible fibers/flyings, the NEC/CEC Zone classification system groups them as follows:  Group IIIC: Atmospheres containing combustible metal dusts. Group IIIC is considered equivalent to Class II, Group E. 

Group IIIB: Atmospheres containing combustible dusts other than combustible metal dusts. Group IIIB is considered equivalent to Class II, Groups F and G.

 Group IIIA: Atmospheres containing solid particles, including fibers, greater than 500 μm in nominal size, which may be suspended in air and could settle out of the atmosphere under their own weight. Rayon and cotton are typical Group IIIA materials. Group IIIA is considered equivalent to Class III. 27.2.3.4 Maximum surface temperature of equipment The maximum surface temperature of equipment includes a temperature classification that is indicated either as a specific maximum temperature value (e.g., T135 °C) or as a specific T-Code value (e.g., T4).

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such as the auto-ignition temperature for explosive gases, or such as the layer or cloud ignition temperature for explosive dusts.

The NEC/CEC Zone classification systems that define the specific T-Code options for flammable gases and flammable/combustible liquid-produced vapors are shown in Table 26.

Table 26 —Class I zone temperature classifications T1 T2 T3 T4 T5 T6

Zones 0, 1, and 2 (≤450 °C) (≤300 °C) (≤200 °C) (≤135 °C) (≤100 °C) (≤85 °C)

For NEC/CEC Zones 20, 21, and 22 combustible dusts and ignitible fibers/flyings, the above T-Code options do not apply. Such equipment is required to indicate the temperature classification by means of a specific maximum temperature value. The use of T-Codes is not an option.

27.3 Area classification for various vessel types 27.3.1 Introduction Locations should be classified in accordance with the general guidance of, and the applicable specific portions of, RP 500, Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2; or RP 505, Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Zone 0, Zone 1, and Zone 2, as applicable.

Recommendations are addressed for specific vessel types in 27.3.2 through 27.3.7 noted below.

27.3.2 All vessels—general Area classification for all vessels in general are as follows: 

Class I, Special Division 1 or Class I, Zone 0: See specific vessel types in the following paragraphs of this subclause.



Class I, Division 1, Group A or Class I, Zone 0, Group IIC: Acetylene bottle storage compartments; open deck areas within 1 m of a natural vent opening, and open areas within 3 m of mechanical exhaust outlets from acetylene bottle storage compartments.



Class I, Division 1, Group B or Class I, Zone 1, Group IIC or Group IIB + H2: Reference 8.2.6 of API RP 500 or API RP 505, as applicable; open deck areas within 1 m of natural vent openings from battery rooms and open areas within 3 m of mechanical exhaust outlets from battery rooms.

NOTE—See 27.7.4 for special wiring requirements for battery rooms.



Class I, Division 1, Group C, Group D, or Groups C and D; or Class I, Zone 1, Group IIA or Group IIB: Flammable and combustible paint products storage and usage areas (reference 8.2.7 of API RP 500 or API RP 505, as applicable); open deck areas within 1 m of natural/room vent openings from paint storerooms; and open areas within 3 m of mechanical exhaust outlets from paint storerooms.

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

Class I, Division 1, Group D or Class I, Zone 1, Group IIA: Helicopter fuel storage areas (reference 11.22 of API RP 500 or RP 505, as applicable).

For classification of adjacent areas, reference 11.23 of API RP 500 or RP 505, as applicable.

27.3.3 Tank vessels and barges This subclause is applicable to tank vessels and barges handling any of the following cargo:  Cargo with closed cup flashpoint below 60 °C  Cargo with closed cup flashpoint over 60 °C and with cargo heating arrangements capable of heating the cargo to within 15 °C of its flashpoint  LPG or LNG  Carbon disulfide  Liquid ammonia, except the weather deck is not classified as a hazardous area  Liquid sulphur  Inorganic acid Hazardous areas: 

Class I, Special Division 1 or Class I, Zone 0: Interiors of cargo tanks and cargo handling rooms and pump rooms.



Class I Division 1 or Class I, Zone 1





Weather locations: Within 3 m of cargo tank vent outlets, cargo tank ullage openings, cargo pipe flanges, cargo valves, cargo handling room entrances, and cargo handling room ventilation openings. Within 5 m of cargo pressure/vacuum valves. Areas within 10 m of vent outlets for the free flow of cargo vapor mixtures and high velocity vent outlets for the passage of large quantities of vapor and air or inert gas mixtures during ballasting, and cargo loading and discharging.



Enclosed spaces: Cargo hose storage spaces. Enclosed space containing cargo piping. Semienclosed (Reference 11.2.1.2 API RP500 or RP505, as applicable) or enclosed space immediately above, below, or adjacent to a cargo tank. A pump room that is continuously ventilated at a minimum of 20 air changes per hour with an audible and visual alarm in a manned space to warn of ventilation failure and a combustible gas detection system installed in accordance with API RP 500-1997 or RP505, as applicable, and with audible and visual alarms located in a manned space that are activated if gas is detected at the levels prescribed

by API RP500 or RP505, as applicable.

Class I, Division 2 or Class I, Zone 2: Open decks over cargo areas and 3 m forward and aft of the cargo area on the open deck and from deck level to an elevation of 3 m above the deck that is not specifically identified elsewhere within this subclause as a Class I, Division 1 hazardous area.

NOTE—Local and regional codes and regulations may involve differences to the classification system requirements for tank vessels detailed in this standard. For example, some codes and regulations may classify an area as Class I, Division 1 that others may classify as Class I, Division 2.

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27.3.4 Vehicle carriers and roll-on/roll-off vessels Vehicle carriers and roll-on/roll-off vessels are as follows: 

Class I, Special Division 1, or Class I, Zone 0: No specified areas.



Class I, Division 1, or Class I, Zone 1: Areas within 0.5 m above vehicle decks.



Class I, Division 2, or Class I, Zone 2: Enclosed and semi-enclosed vehicle decks above 0.5 m from the deck. Open vehicle deck above 0.5 m and below 1 m from the deck.

27.3.5 Mobile offshore drilling units (MODUs) MODUs are to be classified in accordance with API RP500 when the Division system is used and API RP505 when the Zone system is used.

27.3.6 Coal carriers Vessels carrying coal present a unique hazardous situation. Both a coal dust hazard and a methane gas hazard can exist simultaneously. Equipment suitable for use in a combustible dust atmosphere does not typically provide the protection needed in a flammable gas atmosphere, and equipment suitable for use in a flammable gas atmosphere does not typically provide the protection needed in a combustible dust atmosphere. Equipment selection is further complicated by the need for equipment that can withstand compartment hose-down to reduce dust accumulation.

From a coal dust aspect, vessels carrying coal are classified as follows: 

Class II, Division 1 or Zone 20 hazardous locations: Interior of each coil bin and cargo hold.



Class II, Division 1 or Zone 21 hazardous locations: Each compartment that has a coal transfer point (where coal is dropped or dumped). Each open area within 3 m of a coal transfer point. A space that has a coal conveyor on a vessel that carries anthracite coal.



Class II, Division 2 or Zone 22 hazardous locations: Areas within 2 m of a Class II, Division 1 location, except where there is an intervening dust tight barrier, such as a bulkhead or deck. A space that has a coal conveyor on a vessel that carries bituminous coal.

When carrying coal that is known to, or that may emit methane gas, the following shall be fitted: 

A ventilation system shall be provided to holds and adjacent spaces such that ventilation is carried out at a rate of 33 L/min times the maximum weight of coal, in tons, that the ship may carry.



All electrical fittings in cargo holds and adjacent spaces shall comply with the requirements of Class I, Division 1 or Division 2, Group D, or Zone 0, Zone 1, or Zone 2, Group IIA, as applicable, and Class II, Division 1 or Division 2, or Zone 20, Zone 21, or Zone 22, as applicable. If the electrical equipment is of the Class I, Division 2 or Zone 2 type, an interlocking system shall be installed such that the failure of the ventilation system shall remove power from all Division 2 or Zone 2 electrical equipment in the holds or adjacent spaces affected by the ventilation loss.

In areas involving flammable gases or flammable/combustible liquid-produced vapors, electrical equipment may generate temperatures in excess of those permitted for areas involving combustible dusts if the equipment becomes blanketed with coal dust. Therefore, care must be taken to ensure that the installed electrical equipment that can generate heat is certified for operation in both explosive gas and dust atmospheres.

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From a methane aspect, the locations identified in the previous paragraphs are considered Class I, Division 1, Group D; or Class I, Zone 0 or Zone 1, Group IIA locations, as applicable. Electrical equipment installed in these locations should be suitable for the simultaneous presence of combustible dusts and of flammable gases or flammable/combustible liquid-produced vapors. Explosion proof or flameproof equipment that is not watertight should be provided with approved drains.

27.3.7 Dry bulk carriers other than coal carriers Vessels carrying bulk agricultural products that may produce combustible dust hazards are classified as follows: a)

Class II, Division 1 or Zone 20 hazardous locations: Interiors of cargo holds and bins

b)

Class II, Division 1 or Zone 21 hazardous locations

c)

1)

Interiors of spaces where cargo is transferred, dropped, or dumped

2)

Locations within 1 m of the outer edge of the locations described by 1)

Class II, Division 2 or Zone 22 hazardous locations: Areas within 2 m of a Class II, Division 1 location, except where there is an intervening dust tight barrier, such as a bulkhead or deck

27.4 Hazardous locations equipment protection techniques Although NEC/CEC Zone requirements for equipment protection techniques and IEC Zone requirements for equipment protection techniques are similar in certain aspects, the differences can be significant.

Regarding NEC/CEC Zone requirements for equipment protection techniques compared to IEC Zone requirements for equipment protection techniques, the most significant national differences involve the following:  General industrial requirements for the risks of fire, electric shock, and injury to personnel  Hazardous locations code requirements for grounding, bonding, wiring, and markings  Production audit procedures to verify continued compliance These differences are significant enough to not permit interchangeability or possible acceptance of components in most instances. The appropriate authority having jurisdiction, classification society, certification bodies, and other qualified individuals who are familiar with the two different systems should be consulted to determine the acceptability of any hazardous locations electrical equipment or system.

All electrical equipment in hazardous locations should comply with the requirements of either API RP 14F or API RP 14FZ. Certain exceptions and supplemental information are included in this subclause. For situations not addressed by either API RP 14F or API RP 14FZ, or by this subclause, the NEC shall be followed as required by API RP 14F. Marine shipboard cable that complies with IEEE Std 1580-2001 may be used in any area instead of the wiring methods specified in API RP 14F-1999 or API RP 14FZ2001, if installed fittings are approved for the specific hazardous locations and cable type. Cables used in Zone 1 or Division 1 locations must be armored. Unarmored cables may be used in Zone 2 or Division 2 or unclassified locations.

The following protection techniques are suitable for electrical equipment installed in hazardous locations involving flammable gases, flammable liquid-produced vapors, and combustible liquid-produced vapors:

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a)

b)

c)

d)

e)

For Class I, Division 1 1)

Explosion proof

2)

Purged/pressurized (Type X or Y)

3)

Intrinsic safety

4)

Any Class I, Zone 0 techniques for the same gas atmosphere, and with a suitable temperature class

For Class I, Division 2 1)

Non-incendive

2)

Non-sparking

3)

Oil immersion

4)

Hermetically sealed

5)

Sealed

6)

Purged/pressurized (Type Z)

7)

Any Class I, Division 1, Zone 0, Zone 1, or Zone 2 techniques for the same gas atmosphere, and with a suitable temperature class

For Class I, Zone 0 (and Class I Special Division 1 locations) 1)

Intrinsic safety, “ia”

2)

Encapsulation, “ma”

3)

Flameproof, “da”

4)

Class I, Division 1 intrinsic safety technique for the same gas atmosphere, and with a suitable temperature class

For Class I, Zone 1 1)

Flameproof, “db”, “d”

2)

Pressurization, “pxb” or “pyb”

3)

Powder filling, “q”

4)

Oil immersion, “ob”, “o”

5)

Increased safety, “eb”, “e”

6)

Intrinsic safety, “ib”

7)

Encapsulation, “mb”

8)

Any Class I, Division 1 or Zone 0 techniques for the same gas atmosphere, and with a suitable temperature class

For Class I, Zone 2 1)

Type of protection, “n” (“nA”, “nC”, “nL”, “nR”)

2)

Pressurization, “pzc”

3)

Increased safety, “ec” 178 Copyright © 2017 IEEE. All rights reserved.

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4)

Intrinsic safety, “ic”

5)

Encapsulation, “mc’

6)

Flameproof, “dc”

7)

Any Class I, Division 1, Division 2, Zone 0 or Zone 1 techniques for the same gas atmosphere, and with a suitable temperature class

The following protection techniques are suitable for electrical equipment installed in hazardous locations involving combustible dusts and ignitible fibers/flyings: f)

g)

h)

i)

For Class II, Division 1 1)

Dust-ignition proof

2)

Pressurized (Type X or Y)

3)

Intrinsic safety

4)

Any Zone 20 techniques for the same dust atmosphere, and with a suitable temperature class

For Class II, Division 2 1)

Dust tight

2)

Non-incendive

3)

Hermetically sealed

4)

Sealed

5)

Pressurized (Type Z)

6)

Any Class II, Division 1, Zone 20, Zone 21, or Zone 22 techniques for the same dust atmosphere, and with a suitable temperature class

For Zone 20 1)

Protection by enclosure, “ta”

2)

Intrinsic safety, “ia”

3)

Encapsulation, “ma”

4)

Any Class II, Division 1 techniques for the same dust atmosphere, and with a suitable temperature class

For Zone 21 1)

Protection by enclosure, “tb”

2)

Pressurization, “p”

3)

Intrinsic safety, “ib”

4)

Encapsulation, “mb”

5)

Any Class II, Division 1 or Zone 20 techniques for the same dust atmosphere, and with a suitable temperature class

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j)

k)

l)

For Zone 22 1)

Protection by enclosure, “tc”

2)

Pressurization, “p”

3)

Intrinsic safety, “ic”

4)

Encapsulation, “mc”

5)

Any Class II, Division 1, Division 2, Zone 20 or Zone 21 techniques for the same dust atmosphere, and with a suitable temperature class

For Class III, Division 1 1)

Intrinsic safety

2)

Dust tight

3)

Hermetically sealed

4)

Non-incendive

5)

Sealed

6)

Any Zone 20 techniques with a suitable temperature class of not greater than T120 °C (for equipment that may be overloaded) or not greater than T165 °C (for equipment not subject to overloading)

For Class III, Division 2: Any Class III, Division 1, Zone 20, Zone 21 or Zone 22 techniques with a suitable temperature class of not greater than T120 °C (for equipment that may be overloaded) or not greater than T165 °C (for equipment not subject to overloading)

For additional information on protection techniques, see Section 4 of API RP 14F or API RP 14FZ, as applicable, along with the following brief summaries: 

Explosionproof/Flameproof – Type of protection where the enclosure is capable of withstanding an internal explosion and of preventing the ignition of an external atmosphere.



Purged/Pressurized – Type of protection where a protective gas reduces the internal concentration of the explosive atmosphere initially present to an acceptable level, and prevents the entrance of the explosive atmosphere.



Intrinsic safety – Type of protection where the electrical energy is restricted to a level below that which can cause ignition by either sparking or heating effects.



Non-incendive – Type of protection where an arc or thermal effect produced under intended operating conditions is not capable of causing ignition.



Non-sparking – Type of protection where the risk of occurrence of arcs or sparks capable of creating an ignition during conditions of normal operation is minimized.



Oil immersion – Type of protection where electrical equipment immersed in a protective liquid cannot ignite an explosive atmosphere above the liquid or outside the equipment enclosure.



Sealed – Type of protection where the device cannot be opened during normal service and is sealed effectively to prevent entry of an external atmosphere.



Encapsulation – Type of protection where electrical parts are enclosed in a compound in such a way that an explosive atmosphere cannot be ignited.

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

Powder filling – Type of protection where electrical parts are surrounded by filling material to prevent the ignition of an explosive atmosphere.



Increased safety – Type of protection where electrical equipment provides increased security against the possibility of excessive temperatures and of the occurrence of arcs and sparks.



Dust-ignition proof – Type of protection where the enclosure excludes entrance of dusts under normal and abnormal test conditions and does not cause ignition of the external explosive atmosphere.



Dusttight – Type of protection where the enclosure excludes entrance of dusts under normal test conditions and does not cause ignition of the external explosive atmosphere.



Protection by enclosure – Type of protection where the enclosure provides dust ingress protection under normal test conditions, and abnormal test conditions in some instances, and provides a means to limit surface temperatures.

27.5 Hazardous locations equipment markings 27.5.1 NEC and CEC division classification systems Equipment approved for use in Division classified areas in accordance with 27.6 below shall be marked to show the Class, Division, Group (as applicable), and Temperature classification as follows: a)

Class (see 27.2.2.1)

b)

Division (see 27.2.2.2)

c)

Gas or dust group, or specific gas or vapor, as applicable (see 27.2.2.3)

d)

Temperature classification referenced to a 40 °C ambient or higher, if there is a higher upper ambient (see 27.2.2.4)

NOTE 1—Division equipment may be marked in accordance with 27.5.2 below for the applicable Zone as indicated in 27.4 above. When so marked, the “AEx” or “Ex”, and any type of protection technique letter designation, is not included.

NOTE 2—Equipment for use in a range of ambient temperatures other than −25 °C and +40 °C is considered to be special, and the ambient temperature range shall then be marked on the equipment, including either the symbol “Ta” or “Tamb” together with the special range of ambient temperatures. As an example, such a marking might be “–30 °C ≤ Ta ≤ +40 °C.”

27.5.2 NEC and CEC zone classification systems Equipment approved for use in Zone classified areas in accordance with 27.6 below shall be marked to show the Class (for NEC Class I only), Zone, Group, and operating and Temperature classification as follows: a)

Class (see 27.2.3.1)

b)

Zone (see 27.2.3.2)

c)

Symbol “AEx” (for NEC applications) or “Ex” (for CEC applications)

d)

Protection technique letter designation(s)

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e)

Gas or dust group, or specific gas or vapor, as applicable (see 27.2.3.3)

f)

Temperature classification referenced to a 40 °C ambient or higher, if there is a higher upper ambient (see 27.2.3.4)

NOTE 1—Zone equipment may be marked in accordance with 27.5.1 above for the applicable Division as indicated in 27.4 above.

NOTE 2—Equipment for use in a range of ambient temperatures other than −20 °C and +40 °C is considered to be special, and the ambient temperature range shall then be marked on the equipment, including either the symbol “Ta” or “Tamb” together with the special range of ambient temperatures. As an example, such a marking might be “–30 °C ≤ Ta ≤ +40 °C.”

An example of such a required marking is “Class I, Zone 0 AEx ia IIC T6.” An explanation of marking required is shown in Figure 10 follows:

Figure 10 —Explanation of markings required The symbol AEx signifies that the equipment was tested to the appropriate American National (ANSI) Standard. Most appropriate ANSI standards include the ISA/UL 60079 series of standards and are harmonized with the related IEC 60079 series standard. Harmonized standards contain certain national differences. For example, equipment can satisfy IEC requirements without being tested for general industrial fire and shock hazards, as is required in the United States and Canada for ordinary locations equipment. Such testing is required for equipment with the AEx listing. Equipment marked Ex has been certified to meet the appropriate IEC or other non-US national or regional requirements, such as CENELEC (European Community) requirements, which do not require testing for general industrial fire and shock hazards for third-party certification.

27.6 Approved equipment Electrical equipment in hazardous locations should be of a type suitable for such locations (Class, Division or Zone, and Group) and be type tested and certified or listed to a specific American National standard by an independent testing laboratory acceptable to the regulatory authority (authority having jurisdiction).

NOTE—Local and regional codes and regulations may involve differences in the classification system requirements for tank vessels detailed in this standard. For example, some codes and regulations may classify an area as Class I, Division 1 that others may classify as Class I, Division 2.

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27.7 Equipment Installation 27.7.1 Wiring methods It is recommended that wiring methods for hazardous locations follow the practices recommended for Divisions and Zones in API RP 14F and API RP 14FZ, respectively.

27.7.2 Ventilation fans Fans used for ventilating hazardous locations should be the non-sparking type.

27.7.3 Belt drives It is recommended that belt drives in hazardous locations have a conductive belt and have pulleys, shafts, and driving equipment grounded in accordance with NFPA 77-2000.

27.7.4 Battery installations The interior of adequately ventilated (see 11.3.7) rooms containing batteries that are connected to a battery charger that has an output capacity of more than 2 kW (computed from the highest possible charging current and the rated voltage of the battery installation) shall meet the requirements of Class I, Division 2, Group B or Class I, Zone 2, Group IIC or Group IIB + H2, as applicable, but with the additional requirement that all wiring and equipment except the batteries, the jumpers connecting their cells, and the positive and negative battery cable leads shall be suitable for Class I, Division 1, Group B or Class I, Zone 1, Group IIC or Group IIB + H2, as applicable, depending on whether the Division or Zone area classification system is used.

27.7.5 Paint storage or mixing spaces A space for the storage or mixing of paint should follow wiring practices recommended for Class I, Division 1, Group C, Group D, or Groups C and D locations, as appropriate for the materials being stored or mixed, or Class I, Zone 1, Group IIB or IIA locations as appropriate for the materials being stored, as applicable, depending on whether the Division or Zone area classification system is used.

27.7.6 Vehicle spaces Electrical equipment in the vehicle space that is above the Division 2 or Zone 2 location (see 27.3.4) should be totally enclosed or drip proof and protected by guards or screens to prevent the escape of sparks or metal particles under fault conditions.

27.7.7 Tank vessels 27.7.7.1 Distribution systems Electrical distribution systems of less than 1000 V (line-to-line) should be ungrounded. Grounded distribution systems greater than 1000 V and localized systems under 1000 V (such as for engine starting)

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may be used where current resulting from a fault condition would not flow through the cargo tank or other hazardous location.

27.7.7.2 Combustible liquid cargo with a closed cup flashpoint of 60 °C or higher On vessels that carry combustible liquid cargo, all electrical equipment in cargo tanks should be intrinsically safe (Type “ia” for locations classified using the Zone method).

27.7.7.3 Flammable or combustible liquid cargo with a closed cup flashpoint below 60 °C (including bulk liquefied gas carriers), ammonia, liquid sulfur carriers, and inorganic acid carriers All electrical equipment in cargo tanks except submerged cargo pumps and their associated cables should be intrinsically safe (Type “ia” for locations classified using the Zone method).

Loss of overpressure should cause an alarm at a normally attended location.

27.7.7.4 Bulk carbon disulfide Electrical installations on vessels carrying carbon disulfide must have only suitable intrinsically safe electrical equipment in Class I, Division 1 locations. For Class I, Zone 0 locations, Type “ia” equipment must be used. For Class I, Zone 1 locations, Type “ia” or “ib” equipment must be used.

27.7.7.5 Bulk liquefied gas or ammonia Equipment in a hold space of an ammonia carrier that has a cargo tank that is not required to have a secondary barrier should meet the recommendations for a space adjacent to a cargo tank, except that explosion proof lighting is also permitted. Electrical equipment in a space separated by a gastight steel barrier from a hold space having a tank that must have a secondary boundary should meet the requirements for a space adjacent to a cargo tank, except that explosion proof lighting, explosion proof motors operating cargo and ballast valves, and explosion proof general alarm signals are also permitted.

27.7.8 Submerged cargo pumps Submerged cargo pumps should have a low liquid level, motor current, or pump discharge pressure shut-off that automatically removes power to the motor if the pump loses suction. An audible and visual alarm should be actuated at the cargo control station by the shut-off of the motor. There should be a lockable circuit breaker or switch that disconnects power to the motor.

27.7.9 Lighting for cargo handling rooms Where practical, lighting for cargo handling rooms should be through suitable wire-inserted fixed glass lenses in the bulkhead or overhead from a nonhazardous location. Fixed lenses should be constructed as to maintain the gastight and watertight integrity of the structure. The fixture should be designed so venting and re-lamping is performed from the nonhazardous location. The temperature of the lens should not exceed 180 °C in a 40 °C ambient. Where through-bulkhead lighting is impractical, compromises the fire rating of the bulkhead, or cannot provide adequate illumination, explosion proof lighting fixtures should be provided.

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27.7.10 Branch circuits for hazardous spaces At least two lighting branch circuits should be provided for hazardous spaces so that one may be deenergized for re-lamping. Lighting for enclosed hazardous spaces should be switched using double pole switches located outside of the space.

27.7.11 Ungrounded distribution systems Ungrounded distribution systems, except intrinsically safe circuits, feeding or passing through a hazardous location should have a device capable of continuously monitoring the insulation level to ground and giving an audible alarm at a normally attended location when the current exceeds 30 mA. 27.7.12 Vessels carrying coal Vessels carrying coal present a unique hazardous location problem. Both a coal dust hazard (combustible dusts) and a methane gas hazard (flammable gases or flammable/combustible liquid-produced vapors) can exist simultaneously. Equipment suitable for use in a combustible dust atmosphere does not typically provide the protection needed in a flammable gas atmosphere, and equipment for use in a flammable gas atmosphere does not typically provide the protection needed in a combustible dust atmosphere. Equipment selection is further complicated by the need for equipment that can withstand compartment hose-down to reduce dust accumulation.

When carrying coal that is known to, or that may, emit methane gas, the following safety features are recommended: 

A ventilation system shall be provided to holds and adjacent spaces such that ventilation is provided at a minimum rate of 33 l/min times the maximum weight of coal, in tons, that the ship may carry.



All electrical equipment in cargo holds and adjacent spaces shall comply with the requirements of either Class I, Division 1 or 2, Group D or Zone 0, 1, or 2, Group IIA, as applicable, and Class II, Division 1 or 2, or Zone 20, 21 or 22 as applicable. If the electrical equipment is not suitable for Class I, Division 1, Zone 0 or Zone 1, an interlocking system shall be installed such that the failure of the ventilation system shall remove power from all Division 2 or Zone 2 electrical equipment in the holds or adjacent spaces affected by the ventilation loss.

In atmospheres involving flammable gases or flammable/combustible liquid-produced vapors, electrical equipment may generate temperatures in excess of those permitted for combustible dust locations if they become blanketed with coal dust. Therefore, care must be taken to ensure that any installed electrical equipment, particularly equipment that can generate heat, be suitable for the simultaneous presence of combustible dusts and flammable gases and vapors. Equipment that is not watertight should be provided with suitable drains.

28. Ship construction and outfitting 28.1 Storage and installation All equipment should be protected as effectively as possible during storage and installation. From the time diesel engines, gas turbines, generators, switchgear, energy storage, power conversion equipment, drives, and motors (including those for electric propulsion) are completely tested until installation is completed and the vessel placed in service, precautions should be taken to protect the machinery. All equipment should be located in a warehouse and protected during the period of storage to prevent the entrance of 185 Copyright © 2017 IEEE. All rights reserved.

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foreign matter, and to prevent wide and sudden internal temperature changes in the equipment. Covers should be used over all external openings in electrical apparatus.

During storage, machinery should be periodically inspected. When stored for an extended period, equipment should be given any special care recommended by the manufacturer. All shaft-machined surfaces should be thoroughly coated with a suitable rust-preventing compound that can be removed readily. Particular precaution should be taken to protect the equipment during the installation period.

28.2 Spare parts The vessel owner should consider requirements for spare parts for all critical systems on board the vessel.

As part of this consideration are items such as number of like parts in service, importance of the equipment to the safety and seaworthiness of the vessel, delivery time of replacement parts, manufacturers’ recommendations, remoteness of operating area of the vessel, and cost. Spare parts provided should be packaged for long-term storage in the marine environment and secured to avoid damage to the part or the vessel due to vessel motion.

28.3 Documentation Every vessel should be provided with comprehensive sets of as-built electrical installation drawings and instruction books providing complete and detailed information regarding the operation and maintenance of the systems and equipment. Drawings for each system should provide cable routing information, cable identification, cable sizes, loads, protective device settings, circuit data, conductor termination details, and material lists. Calculation of fault currents with associated overcurrent protective device coordination curves should also be provided. Instruction books should include descriptions and illustrations that provide equipment operating instructions, maintenance procedures, test requirements, and spare parts recommendations. A booklet containing the manufacturer's name, size, type, rating, catalog number, or similar identification for all electrical and electronic equipment on the vessel should also be provided for use by shipboard personnel. An as-built one-line diagram of the ship's power generation and distribution system should be permanently installed in a location accessible at all times to the engineering personnel.

29. System operation and maintenance 29.1 Fire extinguishing precautions Arrangements should be made to shut off generators, propulsion motors, propulsion motor drives, and propulsion control power supplies when the fire extinguishing systems are operated.

29.2 Rotating machine cleanliness Both the interior and exterior of machines should be kept free from dirt, dust, oil, or salt. Oil should be prevented from entering the machine with the cooling air. Insulation maintenance should be in accordance with IEEE Std 432 or equivalent IEC requirements. As an excessive accumulation of dirt may eventually ground the coils and cause winding failure, machines that have an accumulation of dirt and oil should be thoroughly cleaned with nonflammable solvents. The ends of the stator and rotor coils should be wiped and any salt coating removed using fresh water, if necessary. It is essential to keep the air ducts in the stator core and the ventilating holes in the rotor retaining rings free from dirt accumulations, as any restriction in 186 Copyright © 2017 IEEE. All rights reserved.

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these passages can seriously interfere with the flow of air necessary for proper cooling. Dirt is also a heat insulator, and accumulations can cause increased temperatures. Vacuum cleaning is the most effective means of cleaning the interior of a machine. If compressed air is used for cleaning, care should be taken to ensure the air stream is free of water and other contaminants. Electrical equipment used in dusty locations should be vacuumed frequently.

DC machines accumulate conductive carbon dust from brush wear and require special attention to prevent the carbon dust from decreasing insulation resistance.

Although generators and motors are constructed with moisture-resistant insulation, the reliability of operation and the equipment life will be enhanced by keeping the insulation clean and dry.

29.3 Care of idle apparatus The insulation resistance should be measured in equipment idle for a long time either during the installation period or due to interrupted service. It is recommended that a log sheet be maintained for recording the insulation resistance monthly, so that deteriorating conditions can be detected.

Cable insulation resistance should be measured by self-contained instruments, such as a direct indicating ohmmeter of the generator type, applying a dc potential of 500 V. Where the operating voltage is greater than 500 V, the test instrument should apply a dc potential approximately equal to the operating voltage.

Where circuits contain solid-state devices, care should be taken to ensure that devices having a voltage rating less than the test voltage are disconnected or shorted-out before the test voltage is applied. The insulation resistance test should be made with all circuits of equal voltage above ground connected together.

Circuits or groups of circuits of different voltages above ground should be tested separately.

29.4 Safety IEEE Std 45.5 provides recommendations for the safe operation of shipboard electrical systems.

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Annex A (informative) Bibliography Bibliographical references are resources that provide additional or helpful material but do not need to be understood or used to implement this standard. Reference to these resources is made for informational use only.

[B1] API Std 541, Form-wound Squirrel Cage Induction Motors-375 kW (500 Horsepower) and Larger.

[B2] CAN/CSA C22.2 No. 38, Thermoset-Insulated Wires and Cables. 37 [B3] CAN/CSA C22.2 No. 45, Rigid Metal Conduit.

[B4] CAN/CSA-C22.2 requirements. 38

No.

60079-0,

Explosive

atmospheres—Part

0:

Equipment—General

[B5] “Electrical Heat Tracing for Surface Heating on Arctic & Polar Vessels to Prevent Snow & Ice Accumulation,” Copyright Material IEEE, Paper No. PCIC-2012-95.

[B6] IEC TR 61800-6, Adjustable speed electrical power drive systems—Part 6: Guide for determination of types of load duty and corresponding current ratings. 39 [B7] IEEE Std C37.21™-2005, IEEE Standard for Control Switchboards. 40, 41 [B8] Lewis, L. R., B. H. Cho, F. C. Lee, and B. A. Carpenter, “Modeling, Analysis and Design of Distributed Power Systems,” IEEE Power Electronics Specialists Conference, 1989, PESC'89. Vol I, pp.152-159.

[B9] Middlebrook, R. D, “Input Filter Considerations in Design and Application of Switching Regulators,” IEEE Industry Applications Society Annual Meeting, 1976 Record, pp. 366-382.

[B10] Resolution MEPC.245(66), 2014 Guidelines on the Method of Calculation of the Attained Energy Efficiency Design Index (EEDI) for New Ships, 4 April 2014.

[B11] Sudhoff, S. D., S. D. Pekarek, S. F. Glover, S. H. Zak, E. Zivi, J. D. Sauer, and D. E. Delisle, “Stability Analysis of a DC Power Electronics Based Distribution System,” SAE 2002.

37 CSA publications are available from the Canadian Standards Association (Standards Sales), 178 Rexdale Blvd., Etobicoke, Ontario, Canada M9W 1R3 (http://www.csa.ca/).

38 CSA publications are available from the Canadian Standards Association (http://www.csa.ca/).

39 IEC publications are available from the International Electrotechnical Commission (http://www.iec.ch) and the American National Standards Institute (http://www.ansi.org/).

40 The IEEE standards or products referred to in Annex A are trademarks owned by the Institute of Electrical and Electronics Engineers, Incorporated.

41 IEEE publications are available from the Institute of Electrical and Electronics Engineers (http://standards.ieee.org/).

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IEEE Std 45.1-2017 IEEE Recommended Practice for Electrical Installations on Shipboard—Design

Annex B (normative) Electric plant load analysis Ship's generating plants must be sized for the anticipated operating load as required by the ship building specification and the one-line diagram. A load analysis is one design consideration required to determine the quantity and capacity of the electrical power generators to select the most optimal electric plant. Load factors (LFs) are crucial to the load analysis but often can vary; the individual characteristics of the vessel and the equipment comprising the load should be considered in the determination of LFs. The load analysis should document that: 

Individual LFs are realistic based on the operating condition of each component or system.



The generating plant size is adequate to support the maximum operating load and is in accordance with all applicable rules and regulations.



The emergency generator is sized for total connected loads with a unity (1.0) LF.

B.1 Operating conditions Operating conditions are used to define the main generators maximum and minimum load, the shore power load, and the emergency generator load. Vessel operating conditions are defined as follows: 

Port – Vessel dockside receiving power from shore facilities or ship main generators.



Anchor − Vessel is at anchor and powered by ship main generators.



Cruise − Vessel is underway normally transiting from one location to another and powered by ship main generators.



Functional − Vessel is underway performing its designed function(s), if other than cruise, and powered by ship main generators. Name can be changed for specific function.



Emergency – Vessel in emergency status with ship main generators unavailable supplying only emergency loads, as defined by regulatory bodies, from the emergency generator or emergency energy storage system (e.g., UPS).



Safe return to port − As required for certain passenger ships, a condition where a ship has suffered damage not exceeding the fire casualty threshold as defined in SOLAS. The ship should be capable of returning to port using its own power, with all essential systems operational and while providing a safe area(s).

Other operating conditions should be added, where appropriate, to characterize major functions of the vessel. In all cases, the worst case operating condition must be captured to reflect the vessel’s largest operating load. Where the ship is operating in diverse outside ambient temperature environments, the extreme winter and summer loads should be calculated separately to reflect the major differences in machinery operation (e.g., air conditioning plants, electric heaters) during these times to likely capture the worst case operating condition.

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B.2 Groupings Individual electric loads are typically grouped together in the electric plant load analysis. The following is an example of group header names and numbering system. The US Navy Expanded Ship Work Breakdown Structure (ESWBS) found in NAVSEA Document S9040-AA-IDX-010/SWBS 5D is also often used.

Grouping of loads should be adjusted depending on ship size and function as follows.

100 –Propulsion 200 –Batteries and Battery Chargers 300 –Power Conversion Equipment 400 –Lighting 500 –Electronics 600 –Navigation Systems 700 –Auxiliaries 800–Heating Ventilating and Air Conditioning Systems 900 –Deck Machinery 1000 –Food Services 1100 –Workshop/Laundry Equipment

B.3 Load factors The load analysis should be prepared and evaluated with the following considerations in mind: a)

Loads should be described by assignment of LFs for the various operating conditions such as port, anchor, cruise, functional, and emergency. The load analysis will normally address the port, anchor, cruise, and emergency load, unless special considerations for the function of the ship require otherwise, e.g., at-sea cargo transfer (functional).

b)

In general, LFs for individual loads are calculated using the following equations. Often, accurate operating load information is not available and LFs become (operating hours per day)/24 h. = Load Factor

Operating (bhp ) Operating hours per day × Rated (bhp ) 24 hours

(B.1)

= Load Factor

Operating ( kW ) Operating hours per day × Rated ( kW ) 24 hours

(B.2)

or

c)

A single LF for group loads may be assigned if they meet one of the following criteria:

d)

Two or more loads operate with a definite relationship to each other (e.g., heating and air conditioning);

e)

When the relationship described in (i) is not clear, but is known to exist (e.g., galley equipment);

f)

When low power loads in the same space can be assigned roughly the same LFs (e.g., radios and electronics).

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g)

Known load data should always be used in lieu of LFs, when available.

h)

Power converters and their efficiencies should be considered, e.g., uninterruptible power supplies, transformers, semiconductor controlled rectifiers (SCRs). Due to efficiency below 1.0, apparent connected loads may be increased due to the conversion equipment.

i)

Loads that are given individual LFs in the analysis should not be additionally assigned a group factor, and vice versa. For example, 0.3 (individual LF) x 0.4 (group LF) = 0.12; either 0.3 or 0.4 could be used, but not 0.12.

j)

Load factors of zero are assigned to equipment that is seldom used. However, special consideration should be given to large infrequently used loads to ensure their use will not coincide with other high-load conditions.

k)

Load factors of 0.9 and 1.0 are used where motors operate at full load for an extended period of time. Where the relationship between operating and rated load is unknown, a 0.9 LF is typically used.

l)

Any standby or duplicate units should be listed and assigned a factor of zero unless they are continuously idling. The primary unit should be assigned an appropriate LF. For example, Auxiliary Seawater Pump #1, LF=0.9; Auxiliary Seawater Pump #2 (Standby), LF=0.0.

m)

The development of standard LFs for given classes of vessels is encouraged, as time and experience permit.

n)

UPS loads that are operating 100% of the time in a 24-hour day should use a LF of 1.0 (0.9 Diversity Factor × 1.15 Service Factor).

o)

During emergency conditions, emergency loads should be assigned a LF of 1.0 unless otherwise allowed by the approval authority. Emergency loads are identified in 7.3.

p)

If the loads for interior lighting are not known, an estimate of 5 W/m2 of deck space for both vital and non-vital lighting loads can be used.

q)

Automatically-started equipment should be provided a LF of 1.0 without regard for spinning reserve if they operate continuously during a 24-hour period.

r)

Transformer loads can be calculated with a LF of 1.0 (0.9 Diversity Factor × 1.15 Service Factor) or by assessing the loads being fed from the transformer taking into account growth to the transformer's full rating. In such case, only the transformer inefficiency (such as LF = 0.03) should be used.

s)

Load factors shown in Table B.4 through Table B.14 are LFs for typical loads. Load factors should be adjusted for actual operating conditions.

B.4 Margins Margin is a factor applied to increase the load estimate to account for estimation uncertainty (the difference between the final actual loads installed and the current load estimate). Margins are applied when summarizing loads for each operating condition. Table B.1 shows typical ranges of various margins. A throttle margin may be added to ensure the generator set prime mover is sized appropriately. A phase imbalance margin may be added to prevent generator overheating caused by phase imbalances. A service life margin may be added to ensure that the delivered ship has sufficient generating plant capacity to handle future electric loads which may be installed during the ship’s life. Loads that are not expected to grow during the ship’s life (for example, propulsion and steering) should not have a service life growth margin applied. Types and sizes of margins should be agreed upon with the ship owner prior to sizing of the electric plant.

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Table B.1—Typical margins for electric plant load analysis Type of margin

Range

Detail design

5% for existing follow on designs to 20% for new first time designs

Construction

5% for existing follow on designs to 20% for new first time designs 6% for small and 3% for large generators 3% for small and 2% for large generators 20% (1%/year for 20 years)

Throttle Phase imbalance Service life growth

B.5 Load analysis summary The individual loads are summarized (with and without margins) for each group and operating condition to provide the expected calculated total loads. Once the ship loads are determined, then the worst case load can be identified.

The load analysis summary should show that the generating plant is adequate to simultaneously carry the loads during the various operating conditions. The on-line availability of the generators needs to be considered where an N-1 design must provide full power with all margins applied under worst case operating conditions with one generator off line for maintenance.

Table B.2—Typical example of a load analysis summary sheet Group

System/Equipment

100 200 300 400 500 600 700 800

Propulsion Batteries And Battery Chargers Power Conversion Equipment Lighting Electronics Navigation Systems Auxiliaries Heating Ventilation And Air Conditioning Systems Deck Machinery Food Services Workshop/Laundry Equipment kW Totals - No Growth Margin Detail Design & Construction Margin (kW) Other Margins, If Applicable (kW) kW Totals - With Margins

900 1000 1100

Conn (kW)

Port (kW)

Anchor (kW)

Summer Cruise (kW)

Winter Cruise (kw)

Emergency (kw)

Below is an example of generator set sizing calculations where the worst case load is used to determine the minimum generator size. In this example, an N-1 generator configuration is used (see 7.1) where all generators are to be of the same size. Once the minimum size is determined, the next higher available generator size should be selected. In a typical ship design, trade-offs must be made to determine the number of generators required. The goal is to use the minimum number of generators to meet requirements.

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Table B.3—Example of generator sizing calculation Assumes 4 Equally Sized Generators Worst Case (Maximum) kW Total With Margins

2591

Divide By N-1 Generators (4 – 1 = 3)

kWe

3

Minimum Size Each Generator

863.7

kWe

Include Paralleled Generators 95 % Factor (see subclause 7.1)

909.2

kWe

Select Next Available Size Generator (Assumed 1000kWe)

1000

kWe

Table B.4—Typical Group 100 propulsion LFs Group

System/Equipment

100-1 100-2 100-3 100-4 100-5 100-6

Propulsion Motor Prop Motor Vent Fan #1, normal Prop Motor Vent Fan #2, alternate Prop Motor Drainage Pump Propulsion Drive, inefficiency Prop Converter Anti-Condensation Heater Prop Transformer Anti-Condensation Heater Barring Gear Motor Control Panel Jacket Water Heater Generator Anti-Condensation Heaters Fuel Oil Purifier Fuel Oil Purifier Heater Lube Oil Purifier Lube Oil Purifier Heater Lube Oil Settling Tank Heater Pod Steering HPU Lube Oil Separator Bow Thruster Bow Thruster Motor Heater Bow Thruster Red Gear Heater Steering Gear Hydraulic Unit Motor Exciter Auxiliary Cycloconverter Supply Prop Generator Auxiliaries Prop Converter Heater Prop Exciter Prop Converter Cooling Fan Prop Harmonic Filter, inefficiency Prop Harmonic Filter Fan Prop Harm Filter Heater Prop Bearing Heater Prop Auxiliaries

100-7 100-8 100-9 100-10 100-11 100-12 100-13 100-14 100-15 100-16 100-17 100-18 100-19 100-20 100-21 100-22 100-23 100-24 100-25 100-26 100-27 100-28 100-29 100-30 100-31 100-32 100-33

In port 0.0 0.0 0.0 0.1 0.0 0.9

At anchor 0.0 0.0 0.0 0.1 0.0 0.9

Summer cruise 0.9 0.9 0.0 0.2 0.05 0.0

Winter cruise 0.9 0.9 0.0 0.2 0.05 0.0

Emergency

0.9

0.9

0.0

0.0

0.0

0.1 0.9 0.3 0.9 0.0 0.0 0.0 0.0 0.2 0.0 0.0 0.0 0.9 0.5 0.0 0.0 0.0 0.9 0.9 0.0 0.0 0.0 0.0 0.9 0.9 0.9

0.1 0.9 0.3 0.0 0.2 0.3 0.9 0.2 0.2 0.0 0.1 0.0 0.9 0.5 0.0 0.0 0.0 0.9 0.9 0.0 0.0 0.0 0.0 0.9 0.9 0.9

0.0 0.9 0.0 0.0 0.9 0.5 0.9 0.4 0.2 0.3 0.5 0.0 0.9 0.5 0.7 0.0 0.9 0.9 0.0 0.9 0.9 0.05 0.9 0.0 0.0 0.9

0.0 0.9 0.0 0.0 0.9 0.5 0.9 0.4 0.2 0.3 0.5 0.0 0.9 0.5 0.7 0.0 0.9 0.9 0.0 0.9 0.9 0.05 0.9 0.0 0.0 0.9

0.0 1.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1.0 0.0 0.0 0.0 0.0 0.9 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

0.0 0.0 0.0 0.0 0.0 0.0

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Table B.5—Typical Group 200 batteries and battery charger LFs Group

System/Equipment

200-1 200-2

Battery Charger Forklift Battery Charger

In port 0.2 0.2

At anchor 0.2 0.2

Summer cruise 0.2 0.3

Winter cruise 0.2 0.3

Emergency 0.0 0.0

Table B.6—Typical Group 300 power conversion equipment LFs Group

System/Equipment

300-1 300-2

480/120 Isolation Transformer Vital Load Transformer

In port 0.9 0.9

At anchor 0.9 0.9

Summer cruise 0.9 0.9

Winter cruise 0.9 0.9

Emergency

Winter cruise 0.9 0.7 0.7 0.1

Emergency

Winter Cruise 0.7 0.7 0.7 0.3

Emergency

1.0 1.0

Table B.7—Typical Group 400 lighting LFs Group

System/Equipment

400-1 400-2 400-3 400-4

Machinery Space Lighting Navigation Lighting Deck Lighting Emergency Lighting

In port 0.9 0.3 0.3 0.1

At anchor 0.9 0.3 0.3 0.1

Summer cruise 0.9 0.5 0.5 0.1

1.0 1.0 1.0 1.0

Table B.8—Typical Group 500 electronics LFs Group

System/Equipment

500-1 500-2 500-3 500-4

Electronic Cooling System IC System Radar Radio

In Port 0.2 0.2 0.1 0.0

At Anchor 0.4 0.2 0.2 0.0

Summer Cruise 0.7 0.7 0.7 0.3

1.0 1.0 1.0 1.0

Table B.9—Typical Group 600 navigation systems LFs Group

System/Equipment

600-1 600-2

Steering Control Gyrocompass System

In Port 0.0 0.0

At Anchor 0.0 0.0

Summer Cruise 0.7 0.7

Winter Cruise 0.7 0.7

Emergency 1.0 1.0

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Table B.10—Typical Group 700 auxiliaries LFs Group

System/Equipment

700-1 700-2 700-3 700-4 700-5 700-6 700-7 700-8 700-9 700-10 700-11 700-12 700-13 700-14 700-15

Fire/Wash Down Pump Bilge/Ballast Pump Distiller Feed/Ejector Pump Distiller Distillate Pump Potable Water Pump Sewage Pump A/C Chill Water Pump A/C Saltwater Circulation Pump Main Steering Gear Pump Jacket Water Heater Pump Main Seawater Pump Fuel Oil Purifier Feed Pump Fuel Oil Service Pump Pre-Lube Pump Main Diesel Generator Lube Oil Purifier Feed Pump Lube Oil Transfer Pump Main Motor Lube Oil Service Pump Main Engine Jacket Water Cooling Pump Main Engine Jacket Water Warmup Pump Main Engine (Low Temp) Feed Water Cooling Pump Bow Thruster Hydraulic Pump Prop De-ionized Water-Glycol Pump Prop Converter Cooling Pump Prop Harmonic Filter Cooling Pump Prop Seawater Cooling Pump

700-16 700-17 700-18 700-19 700-20 700-21 700-22 700-23 700-24 700-25

In Port 0.0 0.1 0.0 0.0 0.2 0.2 0.3 0.3 0.0 0.0 0.9 0.0 0.0 0.0 0.0

At Anchor 0.0 0.1 0.0 0.0 .03 0.2 0.3 0.3 0.0 0.7 0.9 0.3 0.3 0.0 0.3

Summer Cruise 0.0 0.2 0.4 0.4 0.3 0.2 0.7 0.7 0.3 0.0 0.9 0.9 0.9 0.0 0.3

Winter Cruise 0.0 0.2 0.4 0.4 0.3 0.2 0.5 0.5 0.3 0.0 0.9 0.9 0.9 0.0 0.3

Emergency

0.1 0.0 0.0

0.1 0.0 0.0

0.1 0.9 0.9

0.1 0.9 0.9

0.0 0.0 0.0

0.0

0.0

0.9

0.9

0.0

0.0

0.0

0.9

0.9

0.0

0.0 0.0

0.0 0.0

0.0 0.9

0.0 0.9

0.0 0.0

0.0 0.0 0.5

0.0 0.0 0.5

0.9 0.9 0.9

0.9 0.9 0.9

0.0 0.0 0.0

1.0 1.0 0.0 0.0 0.0 0.0 0.0 0.0 1.0 0.0 0.0 0.0 0.0 0.0 0.0

Table B.11—Typical Group 800 heating ventilating and air conditioning systems LFs Group

System/Equipment

At Anchor 0.7 0.0

Summer Cruise 0.7 0.0

Winter Cruise 0.3 0.0

Emergency

AC Compressor Cargo Hold Supply Fan

In Port 0.7 0.9

800-1 800-2 800-3

Cargo Hold Exhaust Fan

0.9

0.0

0.0

0.0

0.0

0.0 0.0

Table B.12—Typical Group 900 deck machinery LFs Group

System/Equipment

900-1 900-2

Anchor Windlass Capstan

900-3

Cranes

In Port 0.0 0.0

At Anchor 0.0 0.0

Summer Cruise 0.0 0.0

Winter Cruise 0.0 0.0

Emergency

0.0

0.0

0.0

0.0

0.0

0.0 0.0

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Table B.13—Typical Group 1000 food services LFs Group

System/Equipment

1000-1 1000-2

Trash Compactor Juice Dispenser

1000-3 1000-4 1000-5

Range/Convection Oven Deep Fat Fryer Refrigerator

In Port 0.2 0.3

At Anchor 0.2 0.3

Summer Cruise 0.2 0.3

Winter Cruise 0.2 0.3

Emergency

0.3 0.3 0.3

0.3 0.3 0.3

0.3 0.3 0.3

0.3 0.3 0.3

0.0 0.0 0.0

0.0 0.0

Table B.14—Typical Group 1100 workshop/laundry equipment LFs Group

System/Equipment

1100-1

Laundry equipment

In Port 0.2

At Anchor 0.2

Summer Cruise 0.2

Winter Cruise 0.2

Emergency 0.0

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