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The ELECTRICAL ENGINEERSecond Quarter 2012

Table of Contents

Under IIEE spotlightSee the different activities conducted by our Chapters in snaphots...

cover story

technical feature

knowing the standardsacademic links

from the members’ point of views

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12

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ABOUT THE COVER:

from the office of the National President

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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.

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.”

Data shows that electrical causes are the number one source of fires, comprising of 39% in 2011....

2012 IIEE BOard OF GOVErnOrS and OFFICErS

National President Jules S. AlcantaraVP-Internal Affairs Gregorio R. CayetanoVP-External Affairs Alex C. CabugaoVP-Technical Affairs Ma. Sheila C. CabarabanNational Secretary Larry C. CruzNational Treasurer Florigo C. VaronaNational Auditor Angel V. De Vera, Jr.Governor-Northern Luzon Efren Nelson F. PleteGovernor-Central Luzon Virgilio S. LuzaresGovernor-Metro Manila Eusebio A. GonzalesGovernor-Southern Luzon Jozane F. JalbuenaGovernor-Bicol Edwin G. ParañalGovernor-Western Visayas Cirilo C. CalibjoGovernor-Eastern/Central Visayas Federico C. MercadoGovernor-Northern Mindanao Remegio B. GonzalesGovernor-Southern Mindanao Benjamin A. ArbosoGovernor-Western Mindanao Richard O. LizardoImmediate Former President Armando R. DiazOfficer-in-Charge Ramon P. Ayaton

IIEE naTIOnaL SECrETarIaT dEParTmEnT HEadS

Administrative Niellisa Joy B. BandongTechnical Ramon P. AyatonMarketing Allen M. PidoMembership Marjorie Aguinaldo-Munoz

PuBLICaTIOnS COmmITTEE

Chairman: Rolito C. Gualvez Vice Chairman: Ronald Vincent M. SantiagoMembers: Ernesto M. Cabral Marvin H. Caseda Glynn Andy O. Gayman Dr. Allan C. Nerves

Roland P. VasquezOverseer: 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, 727-3552, 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 Ma. Sheila C. Cabaraban Editor-in-Chief Rolito C. GualvezAssociate Editor: Ronald Vincent M. Santiago Technical Consultant: Dr. Allan C. NervesAdministrative Officer: Ramon P. Ayaton

Editorial Staff

Editorial Assistant Jenelyn C. Pajutining

advertising and marketing

Account Executive Joan Q. Delos Santos 727-3552 loc. 101 410-1899

Views 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.

---The Electrical Engineer Editorial Board

Electrical Safety month

We 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.

editorial

from the office of the National President Engr. Jules S. alcantara 2012 IIEE National President

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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, 2012 at Violeta’s Cuisine Bar & Grill Santiago City, participated by 230 members.

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

under 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. It was successfully conducted through the collaborative efforts of Engr. Eutiquio M. Guantero, Jr., Senior Protection Engineering Consultant from Central Area, Saudi Electricity Company, SA. IIEE – Camarines norte Chapter held Electrical Safety Fun run

& Family Fun day in celebration of SaFETY EnFOrCEmEnT and aWarEnESS mOnTH, last may 5, 2012

7under spotlightIIEE

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 participated in Bridaga Eskwela project held at City Central School and rizal Central School last may 21 and 22, respectively

IIEE aklan Chapter held a blood-letting activity in coordination with the Philippine red Cross held last april 23.

IIEE negros Occidental Chapter held its 3rd Electrician’s day: Livelihood Program for Brgy. Electricians Orientation Program last april 28, attended by 206 participants.

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IIEE Palawan Chapter held its 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

In celebration with the Electrical Safety awareness month, the IIEE Bataan Chapter showed its support to the Electrical Safety Enforcement and awareness Campaign last may 5.

IIEE Bulacan Chapter held its 2nd IIEE Bulacan Technical Forum 2012 from 8:00am to 5:00Pm last 21 april at the Pavilion of dJ Paradise resort and Hotel along macarthur Highway, Barangay dakila, City of malolos 3000, Bulacan.

IIEE Bulacan Chapter held an Electrical Safety Forum last may 5 at the Pavilion, dJ Paradise resort & Hotel. It was participated by BFP-Bulacan, including Supt romeo P. rillo, BFP Bulacan Provincial Fire marshal, and almost all Bulacan City/municipal Fire marshals; maCEFa representatives; some Bulacan LGu electrical engineers/electrical inspectors; and IIEE Bulacan Chapter members.

The IIEE aklan and antique Chapters successfully hosted the year’s 14th Western Visayas regional Conference held last march 23-24 at La Carmella de Boracay, aklan.

The Ilocos norte Chapter hosted the northern Luzon regional Conference held last april 20-21 at divine Word College of Laoag, Ilocos norte.

UNDER IIEE Spotlight

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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 held on June 16, 2012 in Qatar Bowling Center doha – State of Qatar

The IIEE Cagayan de Oro chapter successfully hosted 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 Zamboanga del norte Chapter has been revived as a chapter, as it held the Oath taking ceremony for the new sets of 2012 chapter officers and fun run activity last may 5, 2012 at Tres marias resort, High way Gulayon, dipolog City.

after eight years, the IIEE Zamboanga Sibugay Chapter decided to elect new sets of Chapter officers last may 6, 2012 at South Wood restaurant Poblacion Ipil Zamboanga Sibugay.

The IIEE Iriga-rinconada chapter participated 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, 2012.

IIEE Southern Cavite Chapter conducted a Barangay Electrician upgrading Course Graduation and awarding of Certificate last april 21

UNDER IIEE Spotlight

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The IIEE-northern Laguna Chapter take part and supports the event SILaKBO 2012 “Sikad-Lakad-Takbo”, originally known as SILaKBO para sa Kalikasan, is a fund raising activity for the Save Silang-Santa rosa river Foundation, Inc. (S3r2), a non-profit organization and partner of the City Government of Santa rosa in the protection and rehabilitation of the Santa rosa Watershed. SILaKBO aims to promote environmental awareness among the various stakeholders in the watershed.”

The IIEE Central Laguna Chapter conducted a technical seminar on Preventing Electrical accidents in Workplace last april 27 attended by 85 participants.

The Electrical Engineer, our quarterly magazine would like to feature technical articles and views submitted by professionals from the different regions and its Chapters.

With this, we would like all regional Governors to coordinate with their respective Chapters the submission of technical articles and views that is intended to be featured in “The Electrical Engineer “. We would appreciate it if you would send your submissions through email at publications_committee@yahoo.com or jen.pajutining@gmail.com on or before the 15th of each month.

For further queries regarding the matter, you may coordinate with our Publications assistant, ms. Jenelyn C. Pajutining at Telephone nos. (02) 727-3552 loc. 107; (02) 448-5211.

The ELECTRICAL ENGINEERBULLETIN

Oath Taking Ceremony of rmE 2011 Special Professional Licensure Board Examination Qatar Passers administer by Philippine Consul Hon. Jabbar adiong held on april 13, 2012 in Caravan Banquet Hall, doha - State of Qatar

The IIEE – Council of Student Chapters held its 26th annual Leadership Workshop last may 18 – 20, 2012 at Engr. Tomas a. mulingbayan’s place in nasugbu, Batangas. Batch 26 aspirants together with IIEE and Workshop Facilitators – after the Election (Welcoming the Batch 26 to the IIEE – CSC Family)

UNDER IIEE Spotlight

Electrical Safety: A Long Term Advocacy

according 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 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 SafetyStrengthening 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 essentials at home and at 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 responseLast 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; (3) Inspection Fees and (4) Requirements in Preparation of Electrical Plans.

The Safety Organization of the Philippines (SOPI) is non-profit, non-governmental national public service organization dedicated to protecting life and promoting health. The said organization 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 Institute advocacy on Electrical SafetyThe Institute of Integrated Electrical Engineers of the Philippines, Inc. (IIEE) and the International Copper Association signed Memorandum of Agreement for a three-year program for the 3-year Electrical Safety Enforcement and Awareness (ESEA) Campaign Project.

The ESEA Campaign project has its 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 this project.

Cover Story

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Cover Story

Last May 21, the IIEE, together with ICASEA launched the ESEA Campaign at the IIEE National Office. The launching featured the motorcade participated by the IIEE Officers and industry partners. A press conference attended by different media personalities was followed after the motorcade.

After the signing of Proclamation 193, the IIEE conducted several activities in relation with the campaign. Series of electrical safety seminar were conducted by the different chapters of the Institute nationwide, and a motorcade to increase the awareness of the general public on the campaign was held in every regional conference. In 2012, the IIEE celebrated the Electrical Safety Month project 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 official ESEA Campaign Project banner.

ESEA Steering Committee Chairman, Hon. Francis V. Mapile conducted an ESEA Seminar participated by 40 electrical practitioners. The seminar included the discussion on Electrical Safety Key Result Areas, The Dangers of Electricity, Electrical Term, Electrical Injuries, Controlling Electrical

Hazards, and the statistics of Fire Incidents due to electrical connections and the same.

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 served as the Resource Speaker of the seminar which was attended by twelve participants and the members of the Academic Affairs Committee members.

The information about electrical safety practices and its implementation is an element to reduce, if not to prevent, the electrical accidents.

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”.

The rolling down of the official banner of the ESEA campaign project witnessed by the IIEE Officers, staff and members of the IIEE Council of Student Chapters

The IIEE Officers, together with the Staff and CSC after the fun run activity

Electrical flyers distribution around the vicinity of Barangay Immaculate Concepcion by the IIEE Staff and the CSC

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Technical Feature

The Evolution of VLF Testing Technologies Over the Past Two Decades

This 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 assetmanagement.

Index Terms— High-voltage techniques, Power distribution, Power distribution faults, Power system reliability, Reliability, Availability, Maintenance, Condition monitoring, Testing, Preventative maintenance.

I. WHY VLF TESTInGHE 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.

In most countries DC-testing is therefore not an approved

testmethod anymore for testing of PE/ XLPE cables, also becauseof 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

Fig. 1. Water trees of critical length can effectively be tested out by using VLF-Test methods [3].

testing at50Hz or resonance frequencies:- 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.On the other hand the effectiveness in finding the

H.T. Putter, D. Götz, F. Petzold, SebaKMT, and H. Oetjen, HDW Electronics

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Technical Feature

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.

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.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.A. VLF COSINE RECTANGULAR TECHNOLOGY

Fig. 3. Relative breakdown voltage for a rod to plane and cables with and without defects for several voltage shapes [12].

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).

The VLF Cosine-Rectangular technology was the first VLF technology available. The systems consisted of a dc-source, aninductance 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 25μF 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].Because of the rectangular shaped voltage it is also

Fig. 2. Withstand voltage as function of the frequency for model cables without and with mechanical defects [11].

a) b)

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Technical Feature

Fig. 5. Polarity reversal of cosine-rectangular voltage.

Fig. 6. Electrical tree growth-rate as function of the voltage for several frequencies and wave shapes [7].

possible to measure a leakage current; this leakage current is an indication for the quality of the insulation/ cable.

B. VLF SINUSOIDAL TECHNOLOGYIn 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 cosine-rectangular 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 FrEQuEnCYIn Figure 6 the electrical tree growth for several waveshapes and frequencies has been plotted against the test voltage [7]. This research clearly indicates that 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.

IV. PraCTICaL EXPErIEnCES

EXAMPLE CITY OF DORTMUNDThe 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.

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Technical Feature

Fig. 8. Breakdowns as function of the test time and fault position [9].

TaBLE 1numBEr OF BrEaKdOWn durInG TESTInG [9]

Polymericinsulation

Paperinsulation

Tested system length (km) 2149 999Breakdowns 91 29Breakdowns 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.However, if we even go further into detail and look to

Fig. 9. a) Incorrect peeling of the isolation with visible PD tracking, joint close before failure. b) Remaining semi-conductive layers.

Fig. 7. Breakdowns as function of the test time [9].

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.

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.

V. OuTLOOKNowadays 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 test2. VLF withstand test at 0.1Hz and 3U03. 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.

Significant workmanship failures could be e.g. un-complete 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).

a) b)

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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 ofexternal influences.

VI. COnCLuSIOnSThe 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.

The evolution in power electronics resulted in maintenance free systems, and also resulted into a higher testing capacitance.

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.

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

[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

[6] N. Jäverberg, H. Edin, “Applied Voltage Frequency Dependence of Partial Discharges in Electrical Trees” Proc. IR-EE-ETK, Stockholm, Sweden, 2009.

[7] E. Neudert, M. Sturm, “Characterization of tree processes in XLPE by PD Measurement at 50 Hz and very low frequencies, ICDI Budapest, 1997.

[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 on-site 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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Technical Feature

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Standards Scope1. dPnS IEC 60034-14:2012

– rotating electrical machines --- Part 14 mechanical vibration of a certain machines with shaft heights 56mm and higher --- measurements, evaluation and limits of vibration severity. (IEC published 2007)ICS 29.160

The part of IEC 60034 specifies the factory acceptance vibration test procedures and vibration limits for certain electrical machines under specified conditions, when unoccupied from any load or prime mover. It is applicable to d c and three-phase a c machines, with shaft heights 56mm and higher and a rated output up to 50 mW. at operational speeds from 120 min-1 up to and including 15 000 min-1.This standard is not applicable to machine mounted in situ, three-phase commutator motors, single-phase systems, vertical waterpower generators, turbine generators greater than 20 mW and machines with magnetic bearings or series-wound machines.note: For machine measured in situ refer to applicable parts of ISO 10816 and ISO 7919.

2. dPnS IEC 60252-1 2012 – aC motor capacitors --- Part 1: General – Performance, testing and rating --- Safety requirements --- Guide for installation and operation (IEC Published 2010)ICS 31.060.31.060.70

This part of IEC 60252 applies to motor capacitors intended for connection to windings of asynchronous motors supplied from a single-phase system having a frequency up to and including 100 Hz, and to capacitors to be connected to three-phase asynchronous motors so that these motors may be supplied from a single-phase system.This standard covers impregnated or unimpregnated capacitors having a dielectric of paper, plastic film, or a combination of both, either metalized or with metal-foil electrodes, with rated voltages up to and including 660V. motor start capacitors are covered by IEC 60252-2. note: The following are excluded from this standard-shunt capacitors of the self-healing type for a.c. power systems of up to and including 1 000 V nominal voltage (see IEC 60831-1)-shunt capacitors of non-self healing type for a.c. power of up to and including 1000 v nominal voltage (see IEC 60831-1)-shunt capacitors for a.c. power systems having a nominal voltage above 1000 V (see IEC 60871-1)-capacitors for induction heat-generating plants operating at frequencies between 40 Hz and 24 000 Hz (see IEC 60110-1)-series of capacitors (see IEC 60143).-coupling capacitors and capacitor dividers (see IEC 60358)-capacitors to be used in power system electronic circuits (see IEC 61071)-small a.c. capacitors to be used for fluorescent and discharge lamps (see IEC 61048).-capacitors for suppression of radio interference (IEC publication under consideration).-capacitors intended to be used in various types of electrical equipment and thus considered as components. -capacitors intended for use with d.c. voltage.The object of this standard is a) formulate uniform rules regarding performance, testing and rating;b) to formulate specific safety rules;c) to provide a guidance for installation and operation.

3. dPnS IEC 60252-2:2012 – aC motor capacitors --- Part 2 motor Start capacitors(IEC published 2010)ICS 31.060.30.31.060.70)

This part of IEC 60252 applies to motor start capacitors intended for connection to windings of asynchronous motors supplied from a single-phase system having the frequency of the mains.This standard covers impregnated or unimpregnated metalized motor start capacitors having a dielectric of paper or plastic films, or a combination of both and electrolytic motor start capacitors with non-solid electrolyte, with rated voltages up to and including 660V.

Draft Philippine National Standards on Rotating Machinery of the Bureau of Product Standards (BPS/TC58)

Knowing the Standards

21

academic link ...

“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, 2012 at IIEE Training room.

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. Juan is the chairman of IIEE Electrical Safety Committee (ESC) and member of the Electrical Safety, Enforcement and awareness (ESEa) Steering Committee.

Faulty wiringaccording to Juan, an estimated of Php 4 billion was loss in the 46,719 fire incidents recorder nation-wide by the Bureau of Fire Protection. He added that most of the findings from these incidents blamed faulty electrical wiring for properties and lives lost.

These conclusions, the ESPC chairman highlighted, conflicted with the electrical practitioners. “ang tagal-tagal nakatayo yung mga building na iyan tapos masusunog dahil sa maling wiring,” Juan followed.

“Yet we forgot that there is also another component of electrical engineering that is maintenance – preventive maintenance,” said the speaker.

Juan later presented the basic concepts on electricity and possible causes of electrical fires. He reiterated that poor maintenance tops the cause list, followed by poor housekeeping, kapabayaan and notable electrical malpractice.

deviation from the Philippine Electrical Code such as usage of higher rated circuit protection, unintentional creation 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 prolong use of temporary wiring system were explained further by Juan as notable electrical malpractice.

Further, Juan reminded the audience that in case of household expansion it is important to adjust “household load based on the current power demand.”

First of the series

In a short program prior the talk, academic affairs Committee Chairman ronald Vincent Santiago said that this is the first of the series of outreach educational programs set by the IIEE professors group with its partner and beneficiary, Barangay Concepcion, Quezon City. The four-storey IIEE national Headquarters in Cubao is under the jurisdiction of Barangay Concepcion.

Barangay Concepcion Chairman Edwin mazo congratulated the group and IIEE for this endeavour. In the same program, he called the outreach as

First of the series for Brgy. Concepcion

Engr. Juan, Resource Speakerm together with the members of the Academic Affairs Committee and the participants of the seminar

Professors Offer Seminar on Electrical Safety by: Kaycee B. Victorio

...academic link

“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.

Santiago heads the nine-member academic affairs Committee with Vice Chairman Ferdinand milan, Lyndon Bague, marita Barrientos, Jorge Bautista, dennis Edward diano, ariel magat, Kristian Carlo Victorio and marianne Yumul.

Engr. Juan answering the queries raised by the participants during the seminar

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

GEnEraTOrSir Jess, 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/0.8pfunit #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 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

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