1
The ELECTRICAL ENGINEER
ABOUT THE COVER:
Second Quarter 2012
Table of Contents
from the office
of the National
President
Under IIEE
spotlight
See the different activities
conducted by our Chapters in
snaphots...
5
6
12
cover story
Data shows that electrical
causes are the number one
source of fires, comprising of
39% in 2011....
14
technical
feature
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.
knowing the
standards
20
academic
links
22
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.”
23
from the
members’ point
of views
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-Munoz
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
editorial
Electrical Safety Month
W
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
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
Advertising and Marketing
Account Executive
Joan Q. Delos Santos
727-3552 loc. 101
410-1899
---The Electrical Engineer Editorial Board
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.
from the office
of the National President
Engr. Jules S. Alcantara
2012 IIEE National President
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 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 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 held Electrical Safety Fun Run
& Family Fun Day in celebration of SAFETY ENFORCEMENT AND
AWARENESS MONTH, last May 5, 2012
under
6
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.
IIEE spotlight
7
UNDER IIEE Spotlight
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 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
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.
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.
8
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 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
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-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
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
9
UNDER IIEE Spotlight
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 nonprofit 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.
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)
The ELECTRICAL ENGINEER
BULLETIN
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.
10
Cover Story
A
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 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 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 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; (3) Inspection Fees and (4) Requirements
in Preparation of Electrical Plans.
The Safety Organization of the Philippines (SOPI) is nonprofit, 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 Safety
The Institute of Integrated Electrical Engineers of the
Philippines, Inc. (IIEE) and the International Copper
Association signed Memorandum of Agreement for a threeyear 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
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.
The IIEE Officers, together with the Staff and CSC after the fun
run activity
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
Electrical flyers distribution around the vicinity of Barangay
Immaculate Concepcion by the IIEE Staff and the CSC
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 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 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”.
13
Technical Feature
The Evolution of VLF Testing Technologies
Over the Past Two Decades
H.T. Putter, D. Götz, F. Petzold, SebaKMT, and H. Oetjen,
T
HDW Electronics
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.
In most countries DC-testing is therefore not an approved
14
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
Fig. 1. Water trees of critical length can effectively be tested out
by using VLF-Test methods [3].
testing at
50Hz 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
Technical Feature
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. 2. Withstand voltage as function of the frequency for model
cables without and with mechanical defects [11].
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
a)
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).
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 25μF at
60kVrms.
Fig. 3. Relative breakdown voltage for a rod to plane and cables
with and without defects for several voltage shapes [12].
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
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
15
Technical Feature
Fig. 5. Polarity reversal of cosine-rectangular voltage.
possible to measure a leakage current; this leakage
current is an indication for the quality of the insulation/
cable.
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
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
testing at lower frequencies e.g. 0.01Hz instead of 0.1Hz
16
Fig. 6. Electrical tree growth-rate as function of the voltage for
several frequencies and wave shapes [7].
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.
However, if we even go further into detail and look to
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].
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.
17
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
18
[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
Technical Feature
19
Knowing the Standards
Draft Philippine National Standards on Rotating Machinery
of the Bureau of Product Standards (BPS/TC58)
Standards
Scope
1.
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.
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.
3.
20
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.
21
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, 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.
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
Faulty wiring
According 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.
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.
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.
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,” 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.
Engr. Juan, Resource Speakerm together with the members of the Academic
Affairs Committee and the participants of the seminar
...academic link
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
“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
Sir 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/0.8pf
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
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