ABOUT THE COVER: Every month of May since last year, IIEE and ESEA Project advocates have been intensifying their campaign on electrical safety awareness and practices at home and in the workplaces. Rightly so, this issue’s cover depicts our advocacy and coverage in our desire as an EE practitioners to encourage everyone to practice electrical safety wherever and whenever we are.
The ELECTRICAL ENGINEER Second Quarter 2012
Table of Contents
from the office of the National President
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Under the 6 IIEE spotlight See the different activities conducted by our Chapters in snaphots...
cover story
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Electrical Safety st Home and In the Workplace
Data shows that electrical causes are the number one source of fires, comprising of 39% in 2011....
technical 14 feature The Evolution of VLF Testing Technologies Over the Past Two Decades This paper describes the evolution of the Very Low Frequency (VLF) testing technology over the past two decades. Since the introduction of the VLF technology not only the technology itself has changed.
academic links
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First of the series for Brgy. Concepcion Profs Offer Seminar on Electrical Safety “When we are talking about electrical engineering, it is also about safety.”
from the 23 members’ point of views
editorial 2012 IIEE Board of Governors and Officers National President VP-Internal Affairs VP-External Affairs VP-Technical Affairs National Secretary National Treasurer National Auditor Governor-Northern Luzon Governor-Central Luzon Governor-Metro Manila Governor-Southern Luzon Governor-Bicol Governor-Western Visayas Governor-Eastern/Central Visayas Governor-Northern Mindanao Governor-Southern Mindanao Governor-Western Mindanao Immediate Former President Officer-in-Charge
Jules S. Alcantara Gregorio R. Cayetano Alex C. Cabugao Ma. Sheila C. Cabaraban Larry C. Cruz Florigo C. Varona Angel V. De Vera, Jr. Efren Nelson F. Plete Virgilio S. Luzares Eusebio A. Gonzales Jozane F. Jalbuena Edwin G. Parañal Cirilo C. Calibjo Federico C. Mercado Remegio B. Gonzales Benjamin A. Arboso Richard O. Lizardo Armando R. Diaz Ramon P. Ayaton
IIEE National Secretariat Department Heads Administrative Technical Marketing Membership
Niellisa Joy B. Bandong Ramon P. Ayaton Allen M. Pido Marjorie Aguinaldo-Muñoz
Publications Committee Chairman: Vice Chairman: Members: Overseer:
Rolito C. Gualvez Ronald Vincent M. Santiago Ernesto M. Cabral Marvin H. Caseda Glynn Andy O. Gayman Dr. Allan C. Nerves Roland P. Vasquez Ma. Sheila C. Cabaraban
The ELECTRICAL ENGINEER The Electrical Engineer is published quarterly by the Institute of Integrated Electrical Engineers of the Philippines, Inc. (IIEE), with editorial and business offices at #41 Monte de Piedad St., Cubao, Quezon City, Philippines. Tel Nos. (632) 722-7383, 7273552, 412-5772, 414-5626, Fax Nos. (632) 721-6442 & 410-1899. Website: www.iiee.org.ph, E-mail: iiee@iiee.org.ph. The present circulation of the magazine is 32,000 copies per issue to members and industry stakeholders. The Electrical Engineer Editorial Board Chairperson Editor-in-Chief Associate Editor: Technical Consultant: Administrative Officer:
Ma. Sheila C. Cabaraban Rolito C. Gualvez Ronald Vincent M. Santiago Dr. Allan C. Nerves Ramon P. Ayaton Editorial Staff
Editorial Assistant Jenelyn C. Pajutining Front Cover Design Randolph Lamzon Advertising and Marketing Account Executive
Joan Q. Delos Santos 727-3552 loc. 101 410-1899
Electrical Safety Month
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e are now in our second year of our Electrical Safety Prevention advocacy after His Excellency President Benigno Simeon Aquino III, signed the “Proclamation No. 193 Declaring the Month of May of Every Year as the Electrical Safety Month” last year. The Electrical Safety Enforcement and Awareness (ESEA) Campaign Project is continuing with their programs through: enhancement of the enforcement of the Philippine Electrical Code (PEC); providing capacity building to improve the skills of local inspectors; increasing awareness of the public on the importance of electrical safety, and strengthening the institutional cooperation between government and industry such as the local government units, developers, and contractors association, among others. Considering that the loss of lives and millions worth of damages can be prevented through increasing the awareness of the general public on electrical safety practices and by educating our people regarding the common unsafe electrical practices, IIEE will continue this crusade. As our slogan aptly expresses -electrical safety starts with me –being an IIEE member, let us encourage the entire IIEE brotherhood, members of our families and households to practice electrical safety.
---The Electrical Engineer Editorial Board
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iews or opinions expressed by the authors of letters, articles and research studies published in The Electrical Engineer DO NOT necessarily reflect the views of the Institute of Integrated Electrical Engineers of the Philippines, Inc. (IIEE). The IIEE trusts the integrity of these authors. The IIEE exercises due diligent review but it is possible that the contents of the articles contributed may not be verified due to time constraints. Articles or visual materials may not be reproduced without written consent from IIEE. The IIEE reserves the right to accept or refuse submitted materials for publication. Articles, reactions and feedback from readers may be sent through e-mail at publications_committee@yahoo.com.
from the office of the National President
2nd Quarter Report Engr. Jules S. Alcantara 2012 IIEE National President his year, the Eight-Point Agenda has been T introduced, guided in all aspects by the newly created core values of the Institute – the IIEE or Integrity, Innovation, Empowerment and Excellence.
1. Implementation of the Amended Constitution and By-laws. The Institute is now implementing the amended Constitution in By-Laws. As a start, the Institute already established the two new regions: (1) Metro Manila (NCR) and (2) Western Mindanao. The Institute appointed Ad Interim Governors for this year to oversee the programs and activities of these two new regions. Engr. Eusebio “Elboy” A. Gonzales serves as the Ad Interim Governor for Metro Manila (NCR) and Engr. Richard O. Lizardo for Western Mindanao. The Western Mindanao is composed on the following chapters: (1) Misamis Occidental; (2) Zamsasulta; (3) Zamboanga Del Norte; (4) Zamboanga del Sur; and (5) Zamboanga Sibugay. The Institute also established the Regional Nominating Committee for the 2013 elections. This committee is composed on Former Regional Governors and Former Chapter Presidents who are not interested to run for office in 2013. This committee will be in charge of the evaluation and recommendation of candidates for this year’s election of 2013 Regional Governors and Regional Governor-At-Large (National Officers). The Institute also reduced the existing Life Membership Fee of PhP 10,000 to PhP 5,000 with the requirement that the member should have been a Regular Member of Good Standing for at least twelve years. 2. Phase 1 of Construction of the New Building The implementation of phase 1 of construction of the new building has already started last May 2012. The construction of this new four-storey building costs PhP10.67M which contractor was determined through an open and competitive bidding. The scope excludes the partitions, the electrical installations and mechanical works. The new four-storey building is constructed on the 117 sq. meters lot beside the existing IIEE Building. This will host Conference/Training Rooms, Training Center, Library, accommodation rooms for transient member-visitors from the provinces, Business Center, Secretariat Offices and Technical Documents Center (TDC). 3. Improving Services through the adoption of performance metrics of the Balance Score Card (BSC) and the empowerment and recognition of Chapters who have demonstrated excellent work of service, innovations and dedication for their members. The National President introduced the Balance Score-Card to the IIEE to improve the IIEE Operations of the National Office and to recognize Chapters who are unselfishly serving its members. This also aims to measure and continually improve the services of the Institute to its members and to the community. Aside from the Most Outstanding Chapter in Small, Big and Foreign Chapter Categories, the Institute also is establishing the Chapters Excellence Awards. The Chapter Excellence Awards aim to empower and recognize the many chapters who provide excellent services and dedication for their members and the community. The award will be based on the following criteria: 1. Financial Perspective (10%); 2. Member Service Perspective (35%); 3. Process Perspective (15%); and 4. Community, Academe and Safety (40%). 4. Improving IIEE Process such as registration, issuance of certificates, technical sessions and license renewals through effective use of technologies such as internet, E-ID’s, accurate membership database, and trained in-house personnel. The IIEE is now on the process of implementing the eCard with network database. About 5000 eCards will be released this year.
5. Expand Information Dissemination through the Effective use of Internet and the IIEE Website and community Works; The establishment of the Official Facebook Page of the Institute is already on its planning stage, headed by the Vice President for Technical Affairs, Engr. Ma. Sheila C. Cabaraban. The said Facebook account will have its authorized moderator and administrator to manage the queries that will be raised in the page. The Institute continues to use its official website to disseminate information to its members and the general membership. Different information can now be viewed in the website such as regional reports, chapter activities, technical papers/articles and announcement of events. The EE Magazine and technical papers can be downloaded from the website. The direct contact information of the IIEE National Secretariat was already posted in the IIEE website. This is to properly address on a timely manner the concerns of the members to the staff-in-charge. Visit the IIEE Webiste: www.iiee.org.ph for more information. 6. Promoting Safety, Energy Efficiency, Power Quality and other advocacies through joint efforts and cooperation with other organizations and groups such as LGU’s, the Board of Electrical Engineering, ICA and among others; About seventeen chapters and the IIEE National Office participated in simultaneous fun run activity by the IIEE’s Electrical Safety Enforcement and Awareness (ESEA) Campaign in celebration with the Electrical Safety Month last May 5, 2012. Different activities in line with this month-long celebration were held after the fun run such as electrical safety inspection in schools, residential and commercial establishments, electrical safety flyers distribution and electrical safety seminars. The IIEE Officers and ESEA Steering Committee members also paid a courtesy visit with DILG Secretary Jesse Robredo last June 15, 2012. The IIEE is tasked by the good Secretary about improving safety through the proper inspection requirements by licensed electrical engineers hired in every city and municipality as mandated by law and proper implementation of safety practices to prevent electrical fires and accidents. Furthermore, the IIEE coordinated with the Bureau of Fire Protection regarding the awareness and implementation of the electrical engineering law. 7. Enhancing skills development program for IIEE Members and students through more extensive technical seminars and conferences. The IIEE National Office, through the Professional Training and Development Committee conducted technical seminars in the IIEE National Office for the quarter. This skills development becomes especially important in light of the Mutual Recognition Agreement among ASEAN countries in the practice of electrical engineering. This will be implemented in 2015 and thus Filipino engineers have to be prepared and competitive in relation to other engineers belonging to other ASEAN countries. The Institute also established the Barangay Electrician Upgrading Program. This program aims to convert our Barangay Electricians and potential out-of-school youth as Registered Master Electricians. An Ad Hoc Committee headed by Governor Rem Gonzales was established to conceptualize the requirements of the program and to come-up with a standard training module for reference of the chapters who will hold an upgrading course. The IIEE also coordinated with the National Electrification Administration (NEA) for its assistance on the implementation of this program. 8. Expanding the call for the electric industry to be prepared for the effects of climate change particularly typhoons and floods and to address carbon emissions; The IIEE has its continuing objectives in promoting renewable energy as a way to address the problems on climate change due to carbon emission. Response to calamities by CEPALCO during the Sendong calamity was extensively discussed during the National Mid-Year Convention.
For full text and more news from the Chapters and Regions, please visit the www.iiee.org.ph
IIEE Isabela Quirino Chapter conducted a technical seminar on Basic Knowledge on Fault Current & Voltage Drop Calculation for Commercial and Industrial Sector last March 9, at Violeta’s Cuisine Bar & Grill Santiago City, participated by 230 members.
IIEE Central Region Chapter Saudi Arabia 4th Technical Seminar was conducted last April 13 at Sitteen Palace Hotel, Riyadh, Kingdom of Saudi Arabia with topic “Substation Automation System (SAS) -- Part 1, through the collaborative efforts of Engr. Eutiquio M. Guantero, Jr., Senior Protection Engineering Consultant from Central Area, Saudi Electricity Company, SA.
IIEE Iloilo Officers with Iloilo Electric Cooperative (ILECO II) Barangay Electricians during the Electrical Safety Seminar and Orientation on Registered Master Electrician Examination held on May 30, at ILECO II H.Q.Site, Brgy. Cau-yan Pototan, Iloilo
IIEE – Camarines Norte Chapter Electrical Safety Fun Run & Family Fun Day in celebration of ELECTRICAL SAFETY ENFORCEMENT AND AWARENESS MONTH, last May 5, 2012
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IIEE Masbate Chapter Officers and members together with the Gawad Kalinga Provincial Head conducts an electrical mission at Gawad Kalinga Village during the 7th Bayani Challenge
IIEE Leyte-Samar Chapter during the Brigada Eskwela project held at City Central School and Rizal Central School last May 21 and 22, respectively
IIEE Aklan Chapter during the blood-letting activity in coordination with the Philippine Red Cross last April 23.
IIEE Negros Occidental Chapter conducting its 3rd Electrician’s Day: Livelihood Program for Brgy. Electricians Orientation Program last April 28, attended by 206 participants.
theIIEE
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UNDER THE IIEE Spotlight
In celebration with the Electrical Safety Awareness Month, the IIEE Bataan Chapter showed support to the Electrical Safety Enforcement and Awareness Campaign last May 5. IIEE Palawan Chapter during General Membership Meeting and technical seminar on Electrical Safety at Work, Dissolved Gas Analysis and Guide for Electrical Testing last March 23 at Skylight Convention Center, Puerto Princesa City, Palawan
IIEE Bulacan Chapter during its 2nd IIEE Bulacan Technical Forum 2012 last April 21 at the Pavilion of DJ Paradise Resort and Hotel along MacArthur Highway, Barangay Dakila, City of Malolos, Bulacan.
The IIEE Aklan and Antique Chapters successfully hosting the year’s 14th Western Visayas Regional Conference last March 23-24 at La Carmella De Boracay, Aklan.
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IIEE Bulacan Chapter during the Electrical Safety Forum last May 5 at the Pavilion, DJ Paradise Resort & Hotel. participated in by Supt Romeo P. Rillo, BFP Bulacan Provincial Fire Marshal, and Bulacan City/Municipal Fire Marshals; MACEFA Representatives; Bulacan LGU electrical engineers/electrical inspectors; and IIEE Bulacan Chapter members.
The Ilocos Norte Chapter hosting the Northern Luzon Regional Conference held last April 20-21 at Divine Word College of Laoag, Ilocos Norte.
UNDER THE IIEE Spotlight
The IIEE Cagayan De Oro chapter successfully hosting the 2012 National Mid-Year Convention and General Membership Meeting last May 24-25 at Grand Caprice, Lim Ket Kai Convention Center, Cagayan De Oro. IIEE-State of Qatar Chapter join the “BOWL for a CAUSE” Fund Raising Project for Princess Jillian and handed over the amount of 2,700QR to the beneficiary Mr. and Mrs. Jonathan Espino on June 16, 2012 in Qatar Bowling Center Doha – State of Qatar
IIEE Zamboanga Del Norte Chapter during the Oath taking ceremony for the new set of 2012 chapter officers and fun run activity last May 5, at Tres Marias Resort, Highway Gulayon, Dipolog City. The IIEE Zamboanga Sibugay Chapter new set of Chapter officers at South Wood Restaurant Poblacion Ipil Zamboanga Sibugay.
The IIEE Iriga-Rinconada chapter in a radio interview at 107.1MBC DWIR-FM with the Bureau of Fire Protection of Iriga City through SF01 Adonis I. Vargas for the information awareness campaign on “Electrical Fires, Cause and Effect” of Residential, Commercial and Institutional establishment last March 18.
IIEE Southern Cavite Chapter poses during a Barangay Electrician Upgrading Course Graduation and Awarding of Certificate last April 21
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UNDER THE IIEE Spotlight
The IIEE-Northern Laguna Chapter take part in supporting SILAKBO 2012 “Sikad-Lakad-Takbo”, a fund raising activity for the Save Silang-Santa Rosa River Foundation, Inc. (S3R2).
Oath Taking Ceremony of RME 2011 Special Professional Licensure Board Examination Qatar Passers administered by Philippine Consul Hon. Jabbar Adiong on April 13, at Caravan Banquet Hall, Doha - State of Qatar
The IIEE Central Laguna Chapter conducting a technical seminar on Preventing Electrical Accidents in Workplace last April 27 attended by 85 participants.
The IIEE – Council of Student Chapters during its 26th Annual Leadership Workshop last May 18 – 20 in Nasugbu, Batangas.
The Professional Regulations Commission and the Board of Electrical Engineering conducting the Oath taking ceremonies of the April 2012 EE Board Passers on June 3 at the SMX Convention Center.
The IIEE Officers, together with the Engr. Jesus C. Santos, Most Oustading Professional in the Field of Electrical Engineering for 2012 during the PRC Awards Night on June 22 at the Manila Hotel
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Cover Story
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Electrical Safety: A Long Term Advocacy
ccording to the first quarter 2012 data of the Department of Interior and Local Government (DILG), faulty electrical connection and faulty electrical appliances are the major causes of fire incidents in the country. Figures generally dropped down as compared to the cases from the same period in 2011, where incidents reportedly went down from 3,479 in the first four months of 2011 to 3,058 on the same period in 2012. Data shows that electrical causes are the number one source of fires, comprising of 39% in 2011. Five out of ten of these fire incidents occurred in Metro Manila. Importance of Electrical Safety Strengthening the measures in educating and information campaign among the residents, communities and establishments is one of the key elements towards an electrically safe environment. Thus, the basic guidelines on electrical safety are essential at home and in the workplace. Residents and employees should not only be aware of these electrical safety guidelines, it is necessary also to instill the importance of applying these safety practices. In an article written by Arthur Vitale, “Knowing proper electrical safety is imperative for safety reasons. One can become shocked, burned or in the worst case scenario a person can be electrocuted which can lead to death by not becoming knowledgeable about electrical safety. One should be aware of basic safety guidelines when working with or around electricity”. (Article Source: http://EzineArticles. com/4392901) . According to the Canadian Centre for Occupational Health and Safety, “the electrical current in regular businesses and homes has enough power to cause death by electrocution. Even changing a light bulb without unplugging the lamp can be hazardous because coming in contact with the "hot" or live part of the socket could kill a person”. In most cases, the improper use of appliances and equipment are the primary cause of electrical related accidents. This is because the general public is not aware of the common unsafe electrical practices at home. In the brochure published by the International Copper Association Southeast Asia, there are five common electrical mistakes in the homes: (1) Octopus Connection, (2) Child’s Play, (3) Overheating Electric Fan, (4) Improper Use of Electrical Appliances, (5) Old Wiring, Improper Wiring. Government and other Organization Response Last June 27, 2011, President Benigno Simeon C. Aquino III signed Proclamation No. 193 declaring the month of May of every year as Electrical Safety Month.
This proclamation has an aim to increase the awareness of the general public on electrical safety through educating them in the safe use of electrical appliances and other equipments. It also aims to emphasize and instill to the public the importance of applying such electrical safety practices. The Department of Labor and Employment (DOLE), established the Occupational Safety and Health Standards with an objective to “protect every workingmen against the dangers of injury, sickness or death through healthful working conditions…” (DOLE OSH Standards). Among of the electrical safety standards that are being used in the country are: (1) Philippine Electrical Code; (2) Electrical Safety Inspection Guide; (3) Inspection Fees and (4) Requirements in Preparation of Electrical Plans. The Safety Organization of the Philippines, Inc. (SOPI), nonprofit, non-governmental national public service organization dedicated to protecting life and promoting health, regularly conducts trainings and seminars such as Basic Occupational Safety and Health Seminar and Fire Code of the Philippines. The Bureau of Fire Protection strengthened its measures in educating residents, particularly in poor communities. Information campaign and regular fire drills are conducted in Metro Manila. The IIEE Advocacy on Electrical Safety The Institute of Integrated Electrical Engineers of the Philippines, Inc. (IIEE) and the International Copper Association signed a Memorandum of Agreement for a three-year program on Electrical Safety Enforcement and Awareness (ESEA) Campaign. The ESEA Campaign has the mission to “ensure ESEA is properly enforced through improving local inspectors’ capacity and to increase the public awareness on electrical safety”. The IIEE established the ESEA Steering Committee and Working Group to facilitate the planning and implementation of the project.
Cover Story Last year, the IIEE, together with ICASEA launched the ESEA Campaign at the IIEE National Office through a press conference attended by different media personalities. In 2012, the IIEE celebrated the Electrical Safety Month through a simultaneous Electrical Safety Fun Run among its different chapters nationwide last May 5. Aside from the fun run, the chapters also conducted electrical safety seminars and electrical flyers distribution among their respective communities. The National Office, through the ESEA Steering Committee, the IIEE National Secretariat and the Council of Student Chapter celebrated the Electrical Safety Month through fun run activity, flyers distribution around the vicinity of Barangay Immaculate Concepcion Cubao and the rolling down of the electrical safety month banner.
The IIEE Officers, together with the Staff and CSC after the fun run activity
ESEA Steering Committee Chairman, Hon. Francis V. Mapile conducted an Electrical Safety Seminar participated by 40 electrical practitioners. The seminar included the discussion on Electrical Safety Key Result Areas, The Dangers of Electricity, Electrical Terms, Electrical Injuries, Controlling Electrical Hazards, and the statistics of Fire Incidents due to electrical connections.
Electrical flyers distribution around the vicinity of Barangay Immaculate Concepcion by the IIEE Staff and the CSC
Last May 12, the Academic Affairs Committee also held a Seminar on Electrical Safety among the residents of Barangay Immaculate Concepcion at the IIEE Seminar Room. Engr.William Juan was the Resource Speaker of the seminar which was attended by twelve participants and the members of the Academic Affairs Committeer. The information about electrical safety practices and its implementation is an element to reduce, if not to prevent, the electrical accidents.
The rolling down of the official banner of the electrical safety month witnessed by the IIEE Officers, staff and members of the IIEE Council of Student Chapters
The ESEA campaign provides this rule of thumb, “Switch off all electrical devices and appliances when not in use, and then unplug them from the socket�.
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Technical Feature
The Evolution of VLF Testing Technologies Over the Past Two Decades H.T. Putter, D. GĂśtz, F. Petzold, SebaKMT, and H. Oetjen, HDW Electronics
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his technical paper is presented by the experts of SebaKMT Dynatronic on cable fault locating, measurement, diagnosis and maintenance, through Engr. Rodolfo R. Penalosa, Former Chairman Board of Electrical Engineering, PRC and President of Westco Electrical & Equipment Corp, exclusive Philippine Representative of SebaKMT Dynatronic. For any clarification, inquiries on which type of test instrument suitable for your application and technical questions on the matter to please contact my email directly; roddy.penalosa@westco-phil.com or call at telephone numbers, 7433691,92 & 93 or fax number 7407602.
Abstract-- Due to the regulation of the electricity market, the reliability of distribution networks becomes more and more important. Network operators are forced to maintain the distribution cable system carefully. Withstand testing after installation or after repair of failures reduces significantly the failure rate during normal operation. This paper describes the evolution of the Very Low Frequency (VLF) testing technology over the past two decades. Since the introduction of the VLF technology not only the technology itself has changed. Because of the large number of systems in operation and the gathered field data/performed researches, also the application has received high attention from the asset management. Index Terms— High-voltage techniques, Power distribution, Power distribution faults, Power system reliability, Reliability, Availability, Maintenance, Condition monitoring, Testing, Preventative maintenance. I. WHY VLF TESTING HE VLF technology was introduced in 1986; the main driver of this technology was the need for a new testingmethod for polymer insulated cables and the enormous problems with water treeing effects in XLPE cables of the 1st generation. Several researches [1], [2] have showed that the traditional DC-testing method on polymer insulated cables induced trapped space charges in the polymeric material. These space charges could be trapped for longer than 24h inside the amorphous regions of the polymeric insulation. If the cable will be re-energized before all space-charges are gone, a local overvoltage will appear which could induce anelectrical tree and result in a breakdown shortly after putting the cable back into operation.
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In most countries DC-testing is therefore not an approved testmethod anymore for testing of PE/ XLPE cables, also because of the other disadvantages of DC-testing like [2]: - It is blind to certain types of defects, such as clean voids and cuts. - It may not replicate the stress distribution existing with power frequency ac voltage. The stress distribution is sensitive to temperature and temperature distribution. VLF Testing also has got its advantages compared to testing at 50Hz or resonance frequencies:
Fig. 1. Water trees of critical length can effectively be tested out by using VLF-Test methods [3].
- Less weight; - Higher output capacity; - Less destructive to the healthy insulation; In figure 2 [11] the withstand voltage as function of the frequency is plotted for XLPE insulated model cables with and without mechanical damages. It can be clearly seen that the breakdown voltage of the cable without mechanical damage is the highest at 0.1Hz, meaning that if a VLF test is performed the healthy insulation is not affected/ aged, whereas at frequencies close to power frequency or higher have a much lower breakdown voltage which indicates that the 50 Hz voltage, stresses the insulation much more than 0.1 Hz VLF voltage.
Technical Feature
These two technologies differ itself in the wave-shape, see figure 4. Apart from the cosine-rectangular and sinusoidal wave-shape there are also systems available with a wave shape that resembles a sine wave. The first two are the most common test methods which each having their own advantages and disadvantages.
Fig. 2. Withstand voltage as function of the frequency for model cables without and with mechanical defects [11]. a)
On the other hand the effectiveness in finding the mechanical damages or water trees is the best at 0.1Hz, see figure 3 [12]. The 3rd and 4th column represent respectively a mechanical defect inside the cable and water trees. As can be seen the breakdown voltage at these defects is the lowest at 0.1Hz and is therefore the most appropriate method for identifying defects in cable insulations.
Fig. 3. Relative breakdown voltage for a rod to plane and cables with and without defects for several voltage shapes [12].
II. EXISTING VLF TECHNOLOGIES The first VLF systems operated on the still existing and proven cosine-rectangular technology. In the early nineties the VLF sinusoidal technology was introduced. These two technologies are still widely used for commissioning testing of newly installed cables and also for maintenance testing of aged cables to eliminate critical weak spots e.g. soaked joints or water-trees with a critical length.
b)
Fig. 4. a) Sinusoidal voltage wave-shape. b) Cosine-Rectangular voltage wave-shape (polarity change resembles a cosine wave with a frequency close to 50Hz).
A. VLF COSINE RECTANGULAR TECHNOLOGY The VLF Cosine-Rectangular technology was the first VLF technology available. The systems consisted of a dcsource, an inductance controlled via a rotor switch and a support capacitor. Because of the evolution in power electronics the rotor-switch has nowadays been replaced by a thyristor switch; resultantly leading to a smaller, lighter and more powerful system. One of the significant advantages of the cosine-rectangular technology is the power recycling during polarity reversal which is based on the resonance principle. Therefore the power-consumption is relatively low and the capacitive load of these systems high. Currently there are systems available with a maximum capacitive load of 25ÎźF at 60kVrms. The polarity reversal of the cosine-rectangular VLFsystems is cosine shaped and has a frequency close to 50Hz, see figure 5, thus the field stress is comparable to operating frequency. A limitation of the cosine-rectangular VLF systems is that this technology needs high efforts for the application with PDdiagnosis or Tan- delta measurement. The latter can be solved by making use of the Hamon approximation [4, 5].
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Technical Feature
Fig. 5. Polarity reversal of cosine-rectangular voltage.
Because of the rectangular shaped voltage it is also possible to measure a leakage current; this leakage current is an indication for the quality of the insulation/ cable.
testing at lower frequencies e.g. 0.01Hz instead of 0.1Hz results in a smaller growth rate of the electrical trees. The difference in growth rate between 0.1Hz and 0.01Hz is roughly 10 times. If we reflect this to the testing time it means that if a test is performed at 0.01Hz the test time should be increased by a factor of 10. This implies for commissioning testing a test time of 10h at 3U0 instead of 1h at 3U0. Moh [8] has confirmed this in his research about the effectiveness of VLF testing in detecting hidden faults. Tests that have been performed at lower frequencies because of the constraints on the capacity of the test set, had an after test failure rate that was more than 3 times higher when compared to tests that have been performed at 0.1Hz. Moreover this research indicates that a VLF test at 0.1Hz, 3U0 is more effective than a 50Hz AC test at 2U0.
B. VLF SINUSOIDAL TECHNOLOGY In the beginning of the nineties the VLF sinusoidal test systems where introduced. These systems already made use of power electronics from the beginning onwards. The evolution of the power electronics resulted in systems with a higher testing capacity, less weight and smaller in size. The principle of the systems is based on an AC-DC-AC convertor. Sinusoidal VLF test systems cannot re-use the power stored in the cable, this stored energy needs to be discharged and is transformed into heat in the discharging resistors. Therefore the capacitive load of sinusoidal systems is in general lower than cosinerectangular systems. The advantage of using a pure sinusoidal wave-shape is that these systems can also be combined with diagnostics like e.g. a PD-diagnosis or a tanDelta measurement. However as the testing frequency differ 500 or 600 times with the operating frequency, the PD characteristics are not the same anymore. A direct correlation of important PD parameter with 50/ 60Hz power frequency has therefore not been given anymore. Moreover a recent research has concluded that the PD seems to die out at lower frequencies [6]. III. INFLUENCE OF THE FREQUENCY In Figure 6 the electrical tree growth for several waveshapes and frequencies has been plotted against the test voltage [7]. This research clearly indicates that
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Fig. 6. Electrical tree growth-rate as function of the voltage for several frequencies and wave shapes [7].
IV. PRACTICAL EXPERIENCES EXAMPLE CITY OF DORTMUND The following example will describe the experiences of the city of Dortmund in VLF testing over a period of 10 years (1987 - 1998). In total more than 3000km of cable has been tested, see table 1. If we look to the number of breakdowns, then most of the breakdowns occurred in heavily aged polymeric cables, in average 4.2 per 100km of tested cable.
Technical Feature
TABLE 1 NUMBER OF BREAKDOWN DURING TESTING [9] Polymeric insulation
Paper insulation
Tested system length (km)
2149
999
Breakdowns
91
29
Breakdowns per 100km
4.2
2.9
If we go more into detail and look to the distribution of the faults over time then we can see that 66% of the faults occurred in the first 10 minutes and 75% in the first 30 minutes, see figure 7. 25% of the faults occurred in the last half hour, this confirms that testing for the full hour is required as recommended by all standards. Same experiences are recorded at other power utilities too.
Fig. 8. Breakdowns as function of the test time and fault position [9].
V. OUTLOOK Nowadays the VLF withstand test is more often combined with a PD-diagnosis. A Dutch power utility e.g. is having the following after-laying test procedure [10]: 1. Sheath test 2. VLF withstand test at 0.1Hz and 3U0 3. PD-diagnosis using damped AC-voltages (DAC) The advantage of additionally performing a PD-diagnosis after the VLF withstand test is that significant workmanship failures, which were not recognised by the VLF test, will be detected and can be repaired on forehand. This will further increase the reliability of the network and reduce costs for unplanned outages, non-delivered energy (e.g. when a wind park is disconnected) or penalty payments.
Fig. 7. Breakdowns as function of the test time [9].
However, if we even go further into detail and look to where the fault occurred, we see that all joint faults occurred within the first 20 minutes, see figure 8. This implies for newly installed cables where the insulation of the cable itself is assumed to be new, a VLF test of 20 minutes will be sufficient.
Significant workmanship failures could be e.g. uncomplete shrinking of a heat-shrink joint, incorrect peeling of the outer semicon-layer or dirt inside joints. These workmanship failures will pass the VLF withstand test but will be detected by a PDdiagnosis. If these workmanship failures are not preventively maintained, joint failures for the next years are expected (depending on the type of failure).
The high number of faults in the XLPE insulation is caused by the poor manufacturing technology of the first generation of XLPE cables with graphitized outer semiconductor layer. Current generations of XLPE cables do not have these problems as the first generation anymore.
a)
b) Fig. 9. a) Incorrect peeling of the isolation with visible PD tracking, joint close before failure. b) Remaining semi-conductive layers.
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Technical Feature Normally after successfully passing the after laying test, the next diagnosis is planned after 10-15 years. In other words, no problems are expected for this time period, unless because of external influences. VI. CONCLUSIONS The VLF Technology has proved its effectiveness over the past two decades for commissioning testing of newly installed cables and also for maintenance testing of aged cables to eliminate critical weak spots.
[3] H.T. Putter, 2007, “Investigation of Water Treeing – Electrical Treeing Transition in Polymeric Insulation of Service Aged Power Cables” TUDelft, Thesis [4] D. Götz, F. Petzold, H. Schlapp, H. Putter, “Dielectric loss measurement of power cables using Hamon Approximation”CMD2010, Tokio, Japan [5] B. V. Hamon, “An approximate method for deducing dielectric loss factor from direct-current measurements,” Proc. IEEE, vol. 99, 151-155, March 1952
The evolution in power electronics resulted in maintenance free systems, and also resulted into a higher testing capacitance.
[6] N. Jäverberg, H. Edin, “Applied Voltage Frequency Dependence of Partial Discharges in Electrical Trees” Proc. IR-EE-ETK, Stockholm, Sweden, 2009.
In comparison to 50Hz or resonance frequencies the VLF technology shows better performances in both identifying insulation faults and leaving the healthy part of the insulation undamaged.
[7] E. Neudert, M. Sturm, “Characterization of tree processes in XLPE by PD Measurement at 50 Hz and very low frequencies, ICDI Budapest, 1997.
The effectiveness of this technology is only given when the frequency of 0.1Hz is used. When using lower frequencies the test time should be increased; this is from both practical and economical point of view not possible or too expensive. Practical experiences have shown that most of the joint failures occur within in the first 20 minutes. If this practical experience is reflected on newly installed cables then the testing time could be reduced to 20 minutes instead of the recommended 60 minutes. In addition to the VLF test nowadays also a PD diagnosis is recommended as part of a commissioning test. With help from PD-diagnostics also small workmanship failures can be found which will further increase the reliability of the network. VII. REFERENCES [1] F.H. Kreuger, “Industrial High DC Voltage”, Delft University Press, 1995 [2] IEEE 400-2001 “IEEE Guide for Field Testing and Evaluation of the Insulation of Shielded Power Cable Systems” IEEE guide
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[8] S.C. Moh, “Very low frequency testing-its effectiveness in detecting hidden defects in cables, 17th international conference on electricity distribution, Cired, Barcelona, 2003. [9] DEW, “Experience report – About 10 years “Voltage onsite Test on Medium Voltage Cable Networks by means of 0.1Hz Cosine Square Wave Voltage” in the 10kV network in the City of Dortmund, Germany, 1998. [10] F. de Vries, 2009 “Experiences with PD measurements on MV cables in wind farms in the Netherlands” F05D IEEE/ICC meeting, Scottsdale, USA [11] E. Gockenbach, “The selection of the frequency range for high-voltage on-site testing of extruded cable systems” IEE Electrical Insulation Magazine Vol. 16 No. 6, pp. 11-16 [12] E. Gockenbach, 2002, “Grundsätzliche Untersuchungen zum Durchschlagverhalten kunststoffisoliertet Kabel bei Spannungen unterschiedlicher Frequenz” BEWAG Symposium Berlin, Germany
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academic link ... First of the series for Brgy. Concepcion Professors Offer Seminar on Electrical Safety by: Kaycee B. Victorio
“When we are talking about electrical engineering, it is also about safety.” These words were simply put by Engr. William Juan, speaker on Electrical Safety Practices Seminar conducted by the Academic Affairs Committee last May 12 at the IIEE Training Room. Engr. Juan said that considering the month of May is declared as Electrical Safety Month, it was apt that the EE educators invited the speaker before barangay officials and residents of Concepcion in Quezon City for a very relevant household topic. Engr. Juan is the chairman of the IIEE Electrical Safety Committee (ESC) and member of the Electrical Safety, Enforcement and Awareness (ESEA) Steering Committee.
Deviation from the Philippine Electrical Code such as usage of higher rated circuit protection, unintentional creation of stray currents and losses in raceways, overload of bus bar capacity, convenience outlet shortage in households, usage of very long extension cords, failure of usage of seal fittings and correct equipment in hazardous locations, lack of proper supervision during construction and prolonged use of temporary wiring system were explained further by Engr. Juan as notable electrical malpractice. Further, Engr. Juan reminded the audience that in case of household expansions it is important to adjust “household load based on the current power demand.” First of the series
Faulty wiring According to Engr. Juan, an estimated of Php 4 billion were lost in the 46,719 fire incidents recorded nationwide by the Bureau of Fire Protection. He added that most of the findings from these incidents blames faulty electrical wiring for properties and lives lost.
In a short program prior to the talk, IIEE Academic Affairs Committee Chairman Ronald Vincent Santiago said that this is the first of a series of outreach educational programs set by the committee with its partner and beneficiary, Barangay Concepcion, Quezon City. The four-storey IIEE National Headquarters in Cubao is under the jurisdiction of Barangay Concepcion.
These conclusions, the ESC chairman highlighted, conflicted with the electrical practitioners. “Ang tagal-tagal nakatayo yung mga building na iyan tapos masusunog dahil sa maling wiring” Engr. Juan said.
Barangay Concepcion Chairman Edwin Mazo congratulated the group and IIEE for this endeavour. In the same program, he called the outreach as
“Yet we forgot that there is also another component of electrical engineering that is maintenance – preventive maintenance,” he followed. Engr. Juan later presented the basic concepts on electricity and possible causes of electrical fires. He reiterated that poor maintenance tops the list, followed by poor housekeeping, kapabayaan and notable electrical malpractice. Engr. Juan together with the members of the Academic Affairs Committee and the participants of the seminar
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...academic link Engr. Santiago heads the nine-member Academic Affairs Committee with Vice Chairman Engr. Ferdinand D. Milan, Engr. Lyndon R. Bague, Engr. Marita S. Barrientos, Engr. Jorge B. Bautista, Engr. Dennis Edward E. Diano, Engr.. Ariel H. Magat, Engr. Kristian Carlo B. Victorio and Engr. Marianne L. Yumul.
Engr. Juan answering the queries raised by the participants during the seminar “pagkakataon para madagdagan ang ating kaalaman” and emphasized the importance of “public awareness” to ensure the safety of the general public from electrical hazards. “Prevention is better than cure” Mazo added. The topic of the second outreach-seminar will be determined from the needs assessment survey conducted to all May 12 attendees. GENERATOR Good day, I am from the office of army chief of engineer, we would like to solicit an assistance with regards to our newly acquired gensets. Our specs requirements are 500kva/400 kw @0.8 p.f. and 34 kVA @ 0.8 p.f. standby output. We have conducted tests on said equipment prior to commissioning, but we doubt that the delivered gensets are underrated since it bears a maximum of 397 kW/397 kva at 1.0 p.f ( for supposed 500 kVA gensets) and 26.3 kW/26.3 kva at 1.0 p.f. using purely resistive dummy load. Your response at the soonest possible time will be one of our basis in recommending the aforementioned gensets to higher HQ for approval in acquiring the equipment. Thank you very much, God bless and more power to our organization. Good afternoon Sir. Herein below is our evaluation of your inquiry. Customer specifications: unit #1; 400kW/500kVA/0.8pf standby ratings unit #2; 27.2kW/ 34kVA/0.8pf standby ratings Situation: A. delivered alternator's nameplate ratings; unit #1; 380kW/475kVA/0.8pf unit #2; nameplate ratings for the 34kVA unit was not mentioned in your report. B. the supplier claims that the 380kW/475kVA/0.8pf is the base load rating and its standby rating is 418kW/522kVA/0.8pf C. load test performed using resistive (1.0pf) load bank, Unit #1; the 380kW/475kVA/0.8pf genset should be able to carry a maximum load of 380kVA @ 1.0pf for the 30 minutes trial that was done. that 380kVA is equal to 380kW @ 1.0pf (resistive) load, that's why. and since it is a brand new unit, the test can go up to a period of 1 hour without problem.
The Academic Affairs Committee awarding the Certificate of Appreciation to Engr. Juan as the Resource Speaker of the said seminar
from the members’ point of view The 397kW/397kVA/1.0pf load test using resistive load bank could have been pushed up a little bit more to attain the specified rating of 400kW. At this point in time, the condition shows that the 380kW/475kVA/0.8pf is likely to be the standby rating of the unit as the supplier claims. A 400kW/500kVA/0.8pf unit will be overloaded if you connect 500kVA resistive load to it. You mentioned in your report that Unit #1 shut down upon reaching 380kW resistive load. I presume that the engine is provided with automatic shutdown against 'low oil pressure', 'high water temperature' and 'overspeed', but not against 100% load. This case is unusual. the supplier, however, says that the manufacturer will check the engine. Similar condition holds true for unit #2. Summary of recommendations: 1. Check the model number from the catalog of the unit and verify if the capacity reflected in the nameplate is standby or base load rating. If the catalog indicates that the capacity indicated for that model is standby rating, then 380kW is not complying with the specifications. same argument holds true for the 27.2kW unit. 2. Test run the units to prove its sound-proof assembly before accepting. Good day, Sir. From Jesus C. Santos, IIEE Chairman, Technical Information Committee