SPECIAL FEATURE
UPS, POWER & ENERGY
ELECTRICAL ENERGY MANAGEMENT SYSTEMS Since the introduction of Appendix 17 in the first edition of the 18th Edition, the electrical industry has seen a steady move and shift in focus towards energy efficiency. With the publication of the 2nd Amendment to the Wiring Regulations, the concept of the prosumer installation has also been introduced, along with a recommendation to measure and monitor energy through the use of an electrical energy management system.
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e can see a shift to energy efficiency and management through other standards and legislation such as ISO50001, IEC60364, BS:EN16247, SECR and ESOS. Although ESOS and SECR legislation is aimed at larger organisations, we can still look at the concepts and requirements and apply these to all sizes of businesses looking to save energy. The traditional concept of an energy user as either purely a consumer or producer is also changing and we are now seeing the idea of a user being both, or being a prosumer. This change in how energy is used and produced has occurred as energy efficiency and renewables have become an increasing part of modern installations. This change needs us to look at new ways to monitor and manage energy usage and energy production and enable the user to use this information to manage an installations’ energy.
Energy management systems
Current sensor directional arrow
To enable this management of energy we need an energy management system (EMS). The purpose of an EMS is to help users to save and monitor their energy by utilising sub-metering, current sensors and monitoring software. The EMS should be capable of measuring and recording energy consumption and automatically sending the metered energy data to a software system through a variety of communication methods, such as RS485, for analysis and reporting on the energy usage.
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Sub-meters Sub-meters are typically seen in a 96x96 form factor and will have a minimum capability to measure active and reactive energy. Additional measurements such as voltage, current, power (W, VA, VAR) and power factor are also common. Modern metering can also enhance the information available to the user by incorporating power quality measurements and monitor for voltage dips, swells, interruptions and harmonics in accordance with BS:EN50160.
Current sensors In order to make the calculation for energy, current measurement is required together with voltage. Current transformers have a primary and secondary current ratio, with the primary current being related to and sized based on the maximum current demand of the conductor, the secondary output of the sensor will be either 5A or 1A. When installing current transformers, it is important to remember they are directional and will have some form of indication on how they need to be orientated during installation. Typically, we will see a moulded arrow on the sensor which should point towards the load – failure to do this will produce incorrect measurement calculations in the metering.
Prosumer installation
Energy management software The final part of the system is the software. The goal of this software is to enable the reporting and management of energy and, increasingly, the power quality of the installation. Remote collection of the measurement data through communication protocols such as RS485 or Ethernet can be automated by the software. The measurements from the sub-metering can then be used to generate automatic reports, with the software sending relevant data to specific people or departments based on what they need to know. By monitoring energy it can be quantified in the same way as other raw materials to help reduce the cost of products or services, with energy consumption data being reported to financial personnel to compare and validate billing data from energy suppliers. Maintenance engineers can have reports on power quality measurements to help identify the possible causes of malfunctions (interruptions, harmonic distortion,
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etc.) and help to manage preventative maintenance activities through the observation of energy inefficiencies. Other aspects of the energy and power usage control can also be automated. By monitoring when and where energy is being used, the EMS can remotely control processes to improve energy efficiency. Power can be turned on or off by sending notifications and managing the automation of processes based on a calendar or on electrical values or events detected by the sub-metering. Environmental measurements such as air quality, temperature and light can also feed into the system to provide valuable information on the installation and provide further information to automate energy consumption.
The future of energy measurement
Sub-meter
As installations continue to move to the new prosumer model, the need for energy to be monitored to ensure a return on investment on power generation systems (renewables) and to manage the energy produced in the most efficient way will become more prevalent. This need for energy management will open up opportunities to install sub-metering and energy management systems to an established customer base driven by regulations, legislation, standards and a desire to reduce energy consumption. Power Quality Expert, powerqualityexpert.com
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24/01/2022 09:29
