That exact unit, along with over 3,000 sold since, is still in operation today.
Winding Resistance with Core Demagnatization
Trouble-Free and Backed by our 5 Year Warranty! Toll free 888 484 3779 | Phone: 267 404 2676 | Fax: 267 404 2685 118 South 2nd St., Perkasie, PA, 18944
www.raytechusa.com
Published by NETA - The InterNational Electrical Testing Association
Raytech stands behind its custom-made, highquality measuring and testing equipment developed and produced for the international power industry.
ANDBOOK
10A and 200A Contact Resistance
In 1997, Raytech demonstrated the durability of its original TR-SPY by throwing it across the room at the NETA New Product Forum.
RANSFORMER
Of All EquipmEnt SOld iS Still in OpErAtiOn tOdAy!
SERIES II
99%
TRANSFORMER HANDBOOK
Single and 3-Phase Ratiometers
SERIES II
Published By
Sponsored by
Raytech U.S.A. Inc.
TRANSFORMERS HANDBOOK
Published by
InterNational Electrical Testing Association
#1
In Customer support
1997 - 2001: TR-Spy Still Supported
2001 - 2010: TR-Spy Mark II Still Supported
2010 - Present: TR-Mark III Still Supported
100%
• Custom-built and quality-tested
Reliable suppoRt foR 100% of the equipment we’ve eveR built!
• Immediate in-field, on-demand customer support
Raytech supports every product we’ve ever introduced.
• Backed by our 5 Year Warranty
You need equipment that remains functional, even after it’s no longer sold. We fully support all of our products for the entire time you own them.
Raytech offers: • Innovation that lasts the life of the product
Raytech stands behind its custom-made, high-quality measuring and testing equipment developed and produced for the international power industry.
Trouble-Free and Backed by our 5 Year Warranty! Toll free 888 484 3779 | Phone: 267 404 2676 | Fax: 267 404 2685 118 South 2nd St., Perkasie, PA, 18944
www.raytechusa.com
Raytech stands behind its custom-made, high-quality measuring and testing equipment developed and produced for the international power industry.
Trouble-Free and Backed by our 5 Year Warranty! Toll free 888 484 3779 | Phone: 267 404 2676 | Fax: 267 404 2685 118 South 2nd St., Perkasie, PA, 18944
www.raytechusa.com
Published by InterNational Electrical Testing Association 3050 Old Centre Avenue, Suite 102, Portage, Michigan 49024 269.488.6382 www.netaworld.org
NOTICE AND DISCLAIMER NETA Technical Papers and Articles are published by the InterNational Electrical Testing Association. Opinions, views, and conclusions expressed in articles herein are those of the authors and not necessarily those of NETA. Publication herein does not constitute or imply any endorsement of any opinion, product, or service by NETA, its directors, officers, members, employees, or agents (hereinafter “NETA”). All technical data in this publication reflects the experience of individuals using specific tools, products equipment, and components under specific conditions and circumstances which may or may not be fully reported and over which NETA has neither exercised nor reserved control. Such data has not been independently tested or otherwise verified by NETA. NETA makes no endorsement, representation, or warranty as to any opinion, product, or service referenced in this publication. NETA expressly disclaims any and all liability to any consumer, purchaser, or any other person using any product or service referenced herein for any injuries or damages of any kind whatsoever, including, but not limited to, any consequential, special incidental, direct, or indirect damages. NETA further disclaims any and all warranties, express or implied including, but not limited to, any implied warranty or merchantability or any implied warranty of fitness for a particular purpose. Please Note: All biographies of authors and presenters contained herein are reflective of the professional standing of these individuals at the time the articles were originally published. Titles, companies, and other factors may have changed since the original publication date. Copyright © 2013 by InterNational Electrical Testing Association, all rights reserved. No part of this publication may be reproduced in any form or by any means, electronic or mechanical, without permission in writing from the publisher.
TRANSFORMERS HANDBOOK TABLE OF CONTENTS Dielectric Response Analysis of Transformers......................................................... 4 Will Knapek and Jeff Foley, OMICRON electronics Corp., USA
Power Transformer Moisture Assessment using Dielectric Frequency Response............ 8 Mats Karlstrom, Matz Ohlen, Peter Werelius, and Brad Morse, Megger
SFRA: The Basics of Swept Frequency Response Testing and Analysis..................... 21 Matt Kennedy and Mario Locarno, Doble Engineering Company
Dry-Type Power Transformers: Understanding Transformer..................................... 26 Ron Widup, Shermco Industries
Abnormal Weather Conditions.......................................................................... 29 Kyle Springinatic, Magna Electric Corp.
Importance of Analyzing Excitation Test Results.................................................... 33 Keith Hill, Doble Engineering Company
Modern Methods in Current Transformer Testing.................................................. 37 Peter Fong, OMICRON electronics Corp., USA
Advanced Diagnostic Testing Methods for Transformers........................................ 39 Charles Sweetser, OMICRON electronics Corp., USA
Ancillary Devices Need Testing Too.................................................................... 44 Rick Youngblood, American Electrical Testing Company
NETA Accredited Companies............................................................................ 51
Published by
InterNational Electrical Testing Association 3050 Old Centre Avenue, Suite 102, Portage, Michigan 49024
269.488.6382
www.netaworld.org
5
Transformers Handbook
DIELECTRIC RESPONSE ANALYSIS OF TRANSFORMERS NETA World, Winter 2009-2010 Issue by Will Knapek and Jeff Foley, OMICRON electronics Corp. USA
You have just come from your annual physical checkup. The doctor has ordered a blood test, and a few of the results have come back out of the normal range. He scheduled you for a few more diagnostic tests such as x-ray, treadmill, and EKG. Those test results are inconclusive. Further tests are required to provide a complete diagnosis. Due to advances in the medical field, tests such as CAT scan and MRI are available. In the power industry there are advanced tests available for transformers when the blood test result (oil test) comes back out of the normal range. In the past, you could do a power-factor test, turns-ratio test, and a windingresistance test to try to diagnose a problem in the transformer. There are new tests available to the power industry where more complete diagnosis can be performed. Tests such as sweep frequency response analysis and dielectric response analysis make the high-end diagnosis possible for transformers, motors, generators, and cables. Let us explore the dielectric response analyzer as diagnostic tool for transformers. During the service life of high-voltage equipment such as power transformers, rotating machines, and cables, insulation systems are subjected to numerous stresses. As a result, a gradual loss in mechanical and dielectric properties will eventually compromise the equipment’s reliability. Moisture is particularly detrimental to paper insulation and is a good indicator of aging. Moisture in transformer insulation can affect transformer performance in several ways. First, it can trigger partial discharge (PD). PD is a discharge of energy in a void or gas bubble. Second, it can generate bubbles in the oil. As the transformer heats, the cellulose will release the moisture that is contained inside. The moisture trapped inside the cellulose will also decrease the dielectric strength of the paper and the oil. This third problem can be seen by performing dielectric strength or breakdown voltage test. Lastly, it can cause the insulation to age prematurely. The first three effects can lead to the premature failure of otherwise healthy transformers. The last issue decreases the life expectancy. Even the best efforts to install a transformer properly provide opportunities where the moisture level can increase in several ways. Faulty seals can allow moisture in the vessel. Exposure during maintenance or repairs is another avenue for water to find its way into the transformer. In addition, normal aging of cellulose
produces water. This is caused by the molecular breakdown of the cellulose which is high in hydrogen and oxygen molecules. The original bonds are broken by what is call depolymerization and the loose hydrogen and oxygen molecules reunite to form H2O, hence water.
MOISTURE ESTIMATION IN INSULATION The only direct method to determine the moisture content in the cellulose is to take paper samples from the transformer and test for moisture content. This is possible only during the repair or tear down of a unit; hence, it is of limited use. There are several indirect methods to determine the moisture content. We can determine the moisture content by measurement of properties that can be related to moisture in the insulation. The first of these indirect methods can be done by moisture in oil measurements. They are easy to conduct, (however, temperature is critical and equilibrium curves must be applied) but often the results have large errors. A traditional method for determining mositure content in a transformer has been an oil sample. Oil samples are easily taken from transformers while they are on-line. This sample is then analyzed by what is called a Karl Fisher titration test (ASTM D1533A). The moisture content measured at the lab temperature would give an indication of the dryness/wetness of the oil. Titration is a chemical reaction where oil is injected into a reaction vessel. The water inside the oil chemically reacts and this is measured. Moisture in paper is then estimated using equilibrium curves or relationships that link moisture in oil to moisture in paper. It is also very important to understand that the cellulose insulation acts like a sponge for moisture. When the transformer is loaded and the winding temperature rises, the moisture is driven from the insulation to the oil. When the transformer cools, the moisture is absorbed back into the cellulose. Since the loading of transformers often varies and the rate that moisture is driven out versus absorbed back in occurs at different rates, it makes oil samples and equilibrium curves problematic. As can be seen from the equilibrium curve in figure 1, the temperature of the oil is an important consideration in applying the curves. Often times, the oil temperature of the transformer is not known, or is recorded arbitrarily at the time of sampling. Further, moisture relationships and curves have limitations to application and accuracy.
6
Transformers Handbook
Figure 1: Moisture Equilibrium Curves It should be noted that moisture in oil is not necessarily an indicator of moisture in paper. The oil moisture content can change quickly during warm up and cool down of a transformer. The volume of water in the cellulose can be as much as 200 percent more than in the oil at the point of equilibrium. That is why it is much more important to know the moisture content of the cellulose than the moisture content of the oil. Another issue with applying the equilibrium diagrams is that these are based on new oil and do not take into account the effects of aging byproducts that are found in older transformer oil.
DIELECTRIC RESPONSE Let us look at the advanced techniques of moisture analysis. The dielectric response is a unique characteristic of the particular insulation system. The increased moisture content of the insulation results in a changed dielectric model and, consequently, a changed dielectric response. By measuring the dielectric response of the equipment in a wide frequency range, the moisture content can be assessed and the insulation condition diagnosed. For the dielectric response test, the test performed is a traditional ungrounded specimen test made from the high voltage winding to the low voltage winding (CHL) in a two winding transformer. We are most concerned with the CHL test, as this is the measurement which contains the most cellulose insulation material. The test connections and modes are the same as used in a traditional transformer insulation power-factor test with the difference being the test is performed at a low voltage, up to 200 Vp-p, and the test is performed at frequencies from 1 kHz to 1μHz. The only other critical data needed to complete the test is the temperature of the oil. Figure 2 is the response curve for oil-impregnated paper. This curve shows a frequency vs. dissipation factor relationship. The higher frequencies display the moisture and aging of the cellulose. Moving from left to right the frequency is reduced and the oil conductivity properties are displayed. In the millihertz range, the insulation geometry comes into play. As the moisture properties of the cellulose change so does the shape of the curve.
Figure 2: Dissipation factor vrs. frequency The most common techniques used to measure this response are frequency domain spectroscopy (FDS) and polarization and depolarization current (PDC) methods. Using the frequency domain spectroscopy, the dissipation factor of the insulation system under test is measured by frequency sweep. The FDS allows fast measurements at high frequencies but requires long measurement times at frequencies down to 0.1 millihertz. The current measurement in the time domain, also called the polarization and depolarization current method, where a dc voltage is applied to the insulation system under test for a specific time and the polarization current is measured. After this, the insulation system is shorted and the depolarization current is measured. From the polarization and depolarization currents the dielectric response is evaluated, and the dissipation factor frequency characteristic is calculated. The PDC method is much faster than the FDS at very low frequencies, but the upper frequency is limited due to the finite rise time of the dc pulses. Measurements in the very low frequencies are important because that is where moisture content is most clearly indicated. Both of these can be compared by transforming the results from the time domain into the frequency domain or vice versa. With improvement in technologies, we can now use two well-established dielectric response measurement techniques together and reduce the time of measurement down to less than three hours whereas with the separate measuring techniques it could take up to eight hours to perform the test. After the test is completed the results must be compared to a standard to determine the actual moisture content. IEC 60422 and IEEE 62-1995 have defined moisture classifications. Some test sets allow the evaluation of the data with consideration of the con-
Transformers Handbook ductivity of the oil which will increase with age. The quality of dielectric response analyzers is not primarily given by the accuracy of the measurement device but rather by the built-in knowledge of the analysis software. One is often faced with the question of “What do these results mean?” Whether the moisture in oil tests (with equilibrium charts) or advanced dielectric response methods are performed, each test technique should lead to some conclusion about the condition of the transformer. Much study and work has been performed in evaluating what to do with moisture results. In some cases, a wet transformer may be vacuum processed, reducing the moisture content to an acceptable level. In cases where the transformer is very old and there is concern that exposing the insulation system to vacuum processing may do more harm than good (further reducing the mechanical strength of the insulation), this information can be used to assist in an assessment as well. In general, dielectric frequency response methods are more accurate than traditional oil sample analysis. Because of this increased accuracy, better decisions can be made and useful life extension solutions can be provided to the end user. So the next time you test transformer oil and still have questions, ask yourself if a more advanced test is needed to completely diagnose the condition of the transformer. __________________________________________________ Will Knapek is an Application Engineer for OMICRON electronics Corp, USA. He holds a BS from East Carolina University and an AS from Western Kentucky University both in Industrial Technology. He retired from the US Army as a Chief Warrant Officer after 20 years of service which 15 were in the power field. He has been active in the testing field since 1995 and is certified as a Senior NICET Technician and a former NETA Level IV technician. Jeff Foley is an Application Engineer for OMICRON electronics Corp, USA. He holds a BSEET from Milwaukee School of Engineering. Jeff has 15 years experience working in the field of power systems testing, maintenance, design and commissioning.
7
8
Transformers Handbook
POWER TRANSFORMER MOISTURE ASSESSMENT USING DIELECTRIC FREQUENCY RESPONSE PowerTest 2010 by Mats Karlstrom, Matz Ohlen, Peter Werelius, and Brad Morse, Megger
Outline:
DFR/FDS – Recent History
• What is DFR?
• 1990’s
• When does DFR testing apply in practice?
– ABB DFR on insulating materials
• What does DFR measure?
– First field DFR instrument Dr. Peter Werelius
• DFR analysis and modeling software
• 1990-2004
• Power Transformer moisture measurements • PF temperature correction
Definition • Dielectric Frequency Response (DFR) – Certain materials will behave a particular way when an electric field is applied – Apply a voltage to insulation and study how it reacts over various frequencies • Frequency Domain Spectroscopy (FDS) – Another name for DFR
Spectroscopy visualization
– Method & technology of DFR developed further • 2004-2009 – CIGRE • Report 254, ”Dielectric Response Methods for Diagnostics of Power Transformers” is published • Project REDIATOOL reported at CIGRE • Task Force D1.01.14 “Dielectric response diagnoses for transformer windings” finalized and to be published • 2009 – IEEE Transformer Committee presentations • 2010 – IEEE Transformer Committee field test guides
Insulation testing/Dielectric response methods
DFR Moisture estimation of paper insulation • Measure Power Factor at multiple frequencies Example: Identify material composition in mineral samples
– At any temperature • Compare measured data with modeled data – Based on reference material database • Result presented as moisture in solid paper – As % of total paper weight and oil conductivity • Added benefit
9
Transformers Handbook • Accurate temperature correction • Ability to detect contamination
When do we use DFR test? • Moisture detection: – Before and after dry out process • Manufacturing facility before & after oven • On site at substation, out of service • With and/or without oil • Commission Test – To ensure dry before going live • Part of regular scheduled maintenance – Monitor moisture content • Suspected problems – Potential internal faults or contamination
Typical Electrical Insulation - Cellulose • Physical cellulose inside transformer – Kraft paper – Pressboard – Winding paper – Sticks – Spacers – Etc • Manufactured to different – Densities – Shapes – Sizes
What does DFR measure? Capacitance = ability for a body to hold a charge
Electrical Insulation
• Isolates live electrical components from ground and other conductors
Typical Failure modes of Electrical Insulation • Moisture • Aging • Heat
• Chemicals • Contaminants • Etc……
Permittivity is material’s ability to transmit (or “permit”) an electric field through polarization of dipoles in the material.
Dielectric Frequency Response – DFR • Measures Capacitance • Measures Power Factor • Measures MOISTURE % in insulation
10
Transformers Handbook
Material Permittivity Changes • Changes in the dielectric material changes the capacitance. • Compare measured values to known insulation dielectric responses.
Q = ε cellulose ⋅ C ⋅V
Q = ε oil ⋅ C ⋅V
How does this apply to Power Transformers? • The insulation between the HV and LV winding can be modeled as a complex capacitance with the following dielectric materials
Q = ε combined ⋅ ε contaminent ⋅ C ⋅ V
Real World Power Transformer Connections
• This is better known as the CHL measurement in P.F. testing • Cellulose – Barriers – Spacers • Oil
Electrical Insulation Circuit Model FDS/DFR Purpose in Power Transformers • Primary - distinguish between moist versus dry paper • Second - indentify contaminants or abnormal influences: – Corrosive Sulfur – Carbon Tracking – Semi-Conductive sludge deposited in ducts between windings – Aging paper as it breaks down – Incorrect shield connections – Ultimately, it leads to a condition assessment of the electrical insulation inside a transformer!
Typically, insulation diagnostics represent insulation impedance as a combination of Capacitance and Power Factor (or Tan Delta).
11
Transformers Handbook What the DFR does (in equations)
Dielectric Frequency Response
• Note, values are frequency dependant (f) • Apply voltage V(f) • Measure loss current I(f) • Calculate Complex Impedance
Z( f )
V( f ) I( f )
• From Complex Impedance Z(f) we can calculate – Capacitance – Resistance – Power Factor (cos θ) – Tan Delta (tan δ) – Dielectric Constant of permeability (ε) • Plot P.F. values at each frequency
Power Factor changes with frequency! Electrical Insulation Modeling – Results Primary Insulation Characteristic Parameters of concern: • Power Factor (Tan Delta) • Capacitance • Permittivity • Frequency of measured values • Temperature
What makes up a typical curve? • Multiple Power Factors plotted against frequency – Standard test consists of : • CHL P.F. (UST) plotted at 19 frequencies (18 min)
Traditional Power Factor Testing
• CH P.F. (GST) plotted at 16 frequencies (7 min) • CL P.F. (GST) plotted at 16 frequencies (7 min)
12
Transformers Handbook
Software Modeling of Transformer geometry
We’ve measured the data. What does it tell us? • Power factors plotted versus varying frequency • How do we interpret? • Modeling Software – Reference model curves • Match measured curve to model • Moisture in solid paper insulation
Measured 500 kVA CHL
An example measurement • 500 kVA ASEA oil filled transformer • 1968 vintage • Free breathing • Stored inside, used for demonstration purposes
Transformers Handbook
Measured 500 kVA CHL Curve imported to modeling software
Measured 500 kVA CHL Curve fitted to reference
13
14
That’s the basic functionality of modeling • Analysis – where does this come from? • Software can actually distinguish between Oil & Cellulose when taking measurements – Oil responds differently than cellulose • Through various frequencies and temperatures – Reference curves 1. OIL response 2. CELLULOSE response 3. TRANSFORMER (Oil and Cellulose combined) response
Typical curve OIL only response This is entirely a characteristic of oil power factor response over frequency
Transformers Handbook
Transformers Handbook
Family of OIL only response View multiple curves to illustrate OIL’S conductivity affect on PF
Typical curve CELLULOSE only response This is entirely a characteristic of CELLULOSE power factor response over frequency
Family of CELLULOSE only response View multiple curves to illustrate CELLULOSE’S moisture affect on PF
15
16
Transformers Handbook
CELLULOSE only response Typical PF values (0-0.5%) @ 60 Hz fall in this range
Typical curve Transformer (OIL and CELLULOSE combined) response
Characteristic Transformer PF Curve = combination of OIL and CELLULOSE response
Oil
Cellulose
Transformers Handbook
Typical curve Transformer response This is entirely a characteristic of Transformer power factor response over frequency
What affects the PF at different frequencies?
CHL – Example: Comparison measurements from a dry vs a wet transformer • Single PF value is not enough to make the right decision • Dielectric Frequency Response tells the story!HL – Example: Comparison measurements from a dry vs a wet transformer
17
18
Transformers Handbook CHL - Example: Contamination
Interpretation of moisture content • < 0.5 % • 0.5 - 1.5% • 1.5 - 2.5% • 2.5 - 4% • > 4%
New transformer Dry insulation Medium wet insulation Wet insulation Very wet insulation
• These values vary with: – Transformer age – Transformer loading – Transformer ambient environment – Transformer size, design – Transformer history
• Interpretation of moisture content of solid insulation (% of weight water per weight cellulose
Measured 500 kVA CHL Curve PF temp correction Algorithm based on Arrhenius equation for combination of cellulose and oil
Transformers Handbook DFR and temperature dependence • Insulation properties changes with temperature • Described by the Arrhenius equation: – κ = κ0·exp(-Wa/kT) – In short: A measurement at e.g. 60 Hz, 20C corresponds to a measurement at higher frequency at higher temperature • Various material have different activation energy (W above) – Non-impregnated paper typically around 1.0 eV – Oil-impregnated paper typically 0.9 – 1.0 eV – Mineral transformer oil typically 0.4 – 0.5 eV
19
20
Comparing moisture estimation methods • Dew Point
Transformers Handbook
Summary and conclusions DFR analysis can:
– Only non-oil filled transformers
• Investigate increased PF in power system components
– Sensitive to equilibrium and temperature
• Estimate the moisture content of oil-immersed cellulose insulation in power transformers, CTs, bushings, PILC etc
– Only surface moisture is indicated – Long wait time for equilibrium at least 12h, typically 24 h • Oil Sampling – Only transformers with oil – Sensitive to temperature and equilibrium – Only surface moisture is indicated • DFR – Oil filled or non oil filled transformers can be tested – Can be measured at any temperature – Average moisture (surface and embedded moisture) – Can be used for Bushings, CT’s, and other paper oil insulations
• Perform individual accurate temperature corrections based on the actual insulation material (s) and condition (patent pending)
21
Transformers Handbook
SFRA: THE BASICS OF SWEPT FREQUENCY RESPONSE TESTING AND ANALYSIS PowerTest 2010 by Matt Kennedy and Mario Locarno, Doble Engineering Company
INTRODUCTION
SFRA WORLDWIDE ACCEPTANCE
In the past several years, SFRA testing has evolved from a design tool to a mainstream test used by hundreds of utilities, industries, and testing companies around the world. This paper introduces the basics of SFRA testing and highlights some interesting cases to illustrate practical application and analysis techniques.
The international community has widely accepted SFRA and is now developing guidelines for its use. Doble Engineering has been active in both the IEEE and IEC organizations in preparing guides and worldwide standards for test methods and analysis of SFRA test results. The following guides will soon be available:
SFRA is a diagnostic tool that provides information about the mechanical integrity of a transformer core, windings, and connections without requiring a technician to climb inside the transformer. It is often used before and after a transformer is moved from one location to another. The premise of SFRA testing is that changes in the frequency response of a winding may indicate winding movement.
• The IEEE C57.149 Working Group is preparing the “Guide for the Application and Interpretation of Frequency Response Analysis for Oil Immersed Transformers.”
The SFRA test process is as follows: 1. Inject a voltage at one end of a winding. 2. See what comes out the other end. 3. Repeat at a variety of different frequencies. 4. Plot the results. 5. Investigate unexpected variations.
PROBLEMS SFRA HAS DETECTED • • • • • • •
Radial deformation (hoop buckling) Telescoped windings Turn-to-turn short circuits in the winding Open-circuited winding High-resistance connections Defects in the core Bulk and local movement
• Members of the International Electrotechnical Commission (IEC) are preparing a similar FRA standard, “Measurement of Frequency Response” under the Power Transformer Technical Committee TC14/PT 60076-18. These documents will lead to greater acceptance of SFRA test techniques and further signify worldwide acceptance.
HOW DOES SFRA TESTING WORK? When SFRA testing is performed on a transformer winding, a signal is injected at one end of the winding and the response is measured at the other end of the same winding. The signal is a sine wave voltage which is swept through a range of 20 Hz to 2 MHz. The response at each frequency is dependent on the complex arrangement of inductance, capacitance, and resistance of the winding. The input and output voltages are measured with reference to ground; this makes the SFRA test a true two-port network, with the need for a ground reference. Usually the shield of the coax test leads is grounded at the base of the bushings. See Figure 1.
WHEN TO PERFORM THIS TEST SFRA is usually performed in the factory before shipment, after transport, at commissioning, during periodic condition assessment, and post fault.
USE SFRA WITH OTHER TESTS While SFRA test results can be useful in isolation, SFRA is particularly telling when used with other diagnostic tools such as power factor, winding resistance, exciting current, oil test results and Leakage Reactance. To a trained tester, the information obtained from these tests tells a story about the condition of a transformer. In many cases, the SFRA test results provide the critical data for understanding the condition of a transformer.
Figure 1: Typical SFRA Test Connections
22
Transformers Handbook
The SFRA measurement is plotted as a voltage ratio that represents the attenuation of the input signal as it passes through the winding; it is recorded in dB across the frequency range.
Although there are many configurations of transformers, SFRA test procedures are relatively straightforward. They can be broken into two groups: open circuit tests and closed circuit tests.
At low frequencies, the response is dominated by inductive elements in the winding, especially the core. At higher frequencies, the response becomes more capacitive. At all frequencies, a combination of an individual inductance and capacitance produces a resonance (a peak or a valley in the response curve).
• Open circuit responses are dominated by the core at low frequencies and are similar to exciting current results in this respect. Different magnetic paths lead to different responses with typical center phase variations. Figure 2 shows sample results.
Figures 2 and 3 show typical responses consisting of many resonances.
• Short circuit responses remove the effect of core at low frequencies and are similar to leakage reactance results in this respect. All three short circuit responses should be close, usually within 0.2 dB deviation of outer phases. See Figure 4 for sample results.
Figure 2: Typical SFRA Result of HV Open-Circuit Tests on a Wye Delta Transformer
Figure 4: Typical SFRA Result of HVSC Short-Circuit Tests on a Delta Wye Transformer
TYPICAL TEST HOOKUPS This section provides typical test hookups for open-circuit and short-circuit tests on Delta Wye transformers. Table 1: Open-Circuit Test Configurations for Delta Wye Transformer Figure 3: Typical SFRA Result of LV Open-Circuit Tests on a Wye Delta Transformer
CONSISTENT TEST CONFIGURATIONS ARE OF CRITICAL IMPORTANCE The SFRA test is very sensitive to such conditions as tap changer positions, oil levels, test lead grounding, and so on. If the test is performed on a transformer in one configuration at the factory and later performed on the same transformer – in a slightly different configuration – in the field, the field results may not match the factory results. If the inconsistency between the two configurations is not recognized, the tester may assume that a deformation exists and waste time, effort, and money in the effort to identify the source of the variation.
23
Transformers Handbook Table 2: Short-Circuit Test Configurations for Delta Wye Transformer
CASE STUDY #1: AUTOTRANSFORMER TRANSPORTATION DAMAGE FOUND USING SFRA
ANALYSIS OF TEST RESULTS
Figure 6: With Oil and Actual Bushings H – X Open Circuit Test
Know what to expect: • Results can vary between units, depending on size and type of unit. • R esults can be different because of magnetization and grounding effects. • V ariations occur with tap changer positions. The standard is 16R, nominal. • Change occurs based on the oil level. • Bushing configuration changes the response. NOTE: A change in the configuration between tests is the single biggest source of confusion. Certain frequency bands indicate different problem conditions: • 20 Hz-2 kHz: Main core deformation, open circuits, shorted turns, residual magnetism • 10 kHz - 20 kHz: Bulk component, shunt impedance • 20 kHz - 400 kHz: Deformation within the main windings • 400 kHz - 1MHz: Tap winding These are general guidelines; every transformer is a little different.
Figure 7: Before and After Comparison of H2 – X2 Open-Circuit Tests As a result of the Swept Frequency Response Tests, an internal inspection was performed, revealing the following conditions: • Y1 lead lying on top of core (Figure 8) • L oose center winding clamping hardware resulting in loss of pressure on the stack (Figure 9) • Loose boards inside the transformer (Figure 10 and 11)
Figure 5: SFRA Analysis Regions
24
Figure 8: Y1 Lead Lies on Top of the Core
Transformers Handbook
Figure 11: Board on Top of Core
CASE STUDY #2: SFRA REVEALS FAULT ON A 120 MVA AUTOTRANSFORMER A fault occurred. No historical data was available and it was unclear if there had been damage to the unit. SFRA testing was done to assess its condition.
Figure 9: Loose Clamping Hardware
Figure 12: Nameplate Data
Figure 10: Loose Boards
25
Transformers Handbook
Based on the SFRA results a recommendation was made for internal inspection. It was discovered that the tertiary winding connections had never been bolted together and that the energy from the fault had pushed the connection apart. It was clear upon inspection that there had been arcing across the connections. This problem might have been caught at the factory if SFRA testing had been performed there.
Figure 13: SFRA Results – Series Winding Open Circuit Tests
Figure 16: Internal Connection Missing Bolted Hardware
CONCLUSION
Figure 14: Short Circuit Test Results – Series Winding
Figure 15: Short Circuit Test Close-up – Inductive Roll off Region – Series Winding
SFRA is a useful addition to your toolset. It should be used with other tests such as power factor, excitation current, TTR, and so on. Used correctly, it will assist you to spot various failure modes and help your transformer assessment process.
1997 - 2001: TR-Spy Still Supported
2001 - 2010: TR-Spy Mark II Still Supported
2010 - Present: TR-Mark III Still Supported
100% Reliable support for 100% of the equipment we’ve ever built!
Raytech supports every product we’ve ever introduced. You need equipment that remains functional, even after it’s no longer sold. We fully support all of our products for the entire time you own them. Raytech stands behind its custom-made, high-quality measuring and testing equipment developed and produced for the international power industry.
Trouble-Free and Backed by our 5 Year Warranty! Toll free 888 484 3779 | Phone: 267 404 2676 | Fax: 267 404 2685 118 South 2nd St., Perkasie, PA, 18944
www.raytechusa.com
26
Transformers Handbook
DRY-TYPE POWER TRANSFORMERS: UNDERSTANDING TRANSFORMER ISOLATION AND NOISE NETA World, Spring 2010 Issue by Ron Widup, Shermco Industries One of the more overlooked aspects of dry-type transformer installations is the removal of shipping bolts and/or shipping blocking material attached to the unit. Questions such as: Should you remove them or leave them connected? What is their purpose? Why does a transformer hum? (Assuming it doesn’t know the words.) We’ll look at these questions and other topics surrounding the dry-type transformers and the noise they make.
THE SHIPPING BOLTS AND BLOCKING Transformer core and coil assemblies are typically very heavy and require supplemental supports prior to shipment so that the unit does not get damaged while being transported from the manufacturer to the job site. It is very important to remove any temporary shipping bolts or blocking materials prior to energization. Also, it is important to loosen or Removal of Temporary remove any bolts that are connected Shipping Bolts is Important to resilient* mounts located on the unit. These resilient mounts are intended to transfer vibration from the core to the frame, and quite often are simply a rubber pad between the core frame and the bottom of the unit. See detail of vibration isolators in Figure 1 and the photograph detail in Figure 2.
Figure 1: Typical Transformer Assembly (Courtesy of Federal Pacific) Reading further in C57.94, to control audible sound sources the core and coil mounting bolts should be adjusted to the manufacturer’s recommendation. Other bolts, fasteners, and devices should be examined for possible audible sound sources.
*Resilient is defined by Merriam-Webster as capable of withstanding shock without permanent deformation or rupture.
WHAT’S THAT BUZZING SOUND? In IEEE C57.94, Recommended Practice for Installation, Application, Operation, and Maintenance of Dry-Type General Purpose Distribution and Power Transformers, they tell us that the audible sound produced by transformers is due to energizing of the core by the alternating voltage applied to the windings. This creates vibrations whose fundamental frequency is twice the frequency of the applied voltage. The vibrations producing audible sound can occur in the core, coil, mounting, and housing. The transmission of sound from the transformer can be by various media such as air, metal, concrete, wood, or any combination. Amplification of audible sound can occur in a given area due to the presence of reflecting surfaces.
Figure 2: Resilient Mount on Dry-Type Transformer (Shermco Industries photo)
27
Transformers Handbook Vibration isolators installed between the transformer and its mount (Figure 2) will reduce case vibration and compensate for slight unevenness of the mount. They should be sized for the appropriate loading at the fundamental frequency. The transformer housing must be securely fastened to the mount to eliminate possible sound generation. Fans used for ventilation should be studied carefully for their contribution to the general audible sound level.
Figure 4: Dry-Type Transformer Construction (Courtesy of Square D) Figure 3: Flexible Bus Connectors (Shermco Industries photo) To control the transmission of audible sound, flexible connections (Figure 3) should be used on all incoming and outgoing cables or bus to reduce vibration transmission. Acoustical absorbing material should be mounted on reflecting surfaces to reduce sound transmission and possible amplification, and transformers should be mounted on a firm support having as great a mass as possible. Vibration pads or properly designed springs will reduce transmittal of sound considerably. A careful study of the location of vaults within buildings can go far toward not only reducing sound but also reducing complaints. If practicable, vaults should not abut sleeping areas, study areas, or other frequently occupied areas where the ambient sound level is low. Interrupting the sound transmission medium can also be considered during initial vault or pad construction. This could include installing sound absorbing foam, etc., in ceilings and walls or separating the transformer pad from foundation construction. And finally, in C57.94 it says in 5.1.2.2 that after the transformer is placed in permanent position, shipping braces should be removed, and shipping bolts, if present, should be loosened or removed per manufacturer’s recommendations.
WHERE DOES THE SOUND COME FROM? Noise is caused by magnetostricition (changes in shape) of the core laminations while the transformer is energized. Transformers emit a low-frequency, tonal noise that people living in their vicinity experience as an irritating “hum” and can hear even against a noisy background. The electrical power industry produces a range of solutions to abate humming, which originates in the transformer’s core and, when it is loaded, in the coil windings. Core noise is generated by the magnetostriction of the core’s laminations when a magnetic field passes through them. It is also known as “noload noise,” as it is independent of the load passing through the transformer. As the phenomenon occurs it causes air columns to be formed in the spaces between the transformer core and the low-voltage windings of the core and other adjacent parts of the transformer, and these air columns cause audible noise as it moves between the various parts of the transformer. Magnetostriction takes place at twice the frequency of the supply load: for a 60 Hz supply frequency, a lamination vibrates at 120 cycles per second, and the higher the density of the magnetic flux, the higher the frequency of the even number harmonics.
28
Figure 5: Dry-Type Transformer in the Field (Shermco Industries Photo) Also, the audible sound produced by fan-assist cooled (FAC) transformers is partially due to the energizing of the core by the alternating voltage applied to the windings and also by the fans forcing air through the coils. The noise generated by the core, and whose fundamental frequency is twice the frequency of the applied voltage, will create audible sound that will be present even under no load conditions. The vibrations producing audible sound can occur in the core, coil, mounting, housing, and in the conduit. The transmission of sound from the transformer can be by various media such as air, metal, concrete, wood or any combination. Amplification of audible sound can occur in a given area due to the presence of reflecting surfaces. Transformer hum also arises through the vibration caused when the load current passes through the windings, interacting with the leakage flux it generates. This “load noise” level is determined by the size of the load current.
CONTROL OF TRANSFORMER SOUND TRANSMISSION Acoustical-absorbing material should be mounted on reflecting surfaces to reduce sound reflection and possible amplification. Transformers should be mounted on a firm support having as great a mass as possible. Vibration pads or properly designed isolation mounts under the transformer will reduce transmittal of sound. The neoprene rubber isolation pads (Figure 2) provided with the unit should be installed between the transformer and its mounting surface. This will reduce case vibration and compensate for slight unevenness of the mount. Care must be taken to ensure proper and tight installation of conduit. Flexible conduit is recommended. A normal conversation is typically 60-70 dB. OSHA has an actionable level to sound exposure at 85 decibels whenever noise levels equal or exceed an eight-hour time-weighted average sound of 85 decibels, or a dose of fifty percent (29 CFR 1910.95(c)(1). Per General Electric Installation Guide No. 475A667AAP008, dry type transformers are designed and manufactured to comply with NEMA and ANSI standards. The decibel values referenced below (Figure 6) represent average values obtained in a sound laboratory per industry standard test procedures.
Transformers Handbook
Figure 6: Average Sound Levels for Dry-Type Transformers (Courtesy of General Electric) Noise is defined by Merriam-Webster as any sound that is undesired or interferes with one’s hearing of something. So who is to say what sound is undesired or interferes with something? What may be a calming sound of transformer (humming to some), may be a nuisance to others. Just as rock concerts may be annoying to some, and the loud music and rhythm may be stimulating and desirable to others. And since different people have different opinions as to what is acceptable and what is not, and how annoying a transformer has become is different in different situations, the best tactic is to try and mitigate the problem on the front end through proper placement and design, and when initially tested and commissioned make sure you carefully inspect the shipping bolts, packing materials, and resilient mounts so sound is kept at a minimum. Removal or loosening of the shipping bolts will allow for a smooth transfer of vibration and should reduce the overall noise generated by the unit. Ssshhh! I need to listen to the hum, it’s just getting to the good part. Ron. A. Widup, Executive Vice President/ General Manager of Shermco Industries, Inc. has over 20 years of experience in the low-, medium-, and high-voltage switchgear and substation market. He is a principal member of NFPA Technical Committee 70E Standard for Electrical Safety in the Workplace and a member of NEC Code Panel 11. He is past president of NETA and currently a member of the Board of Directors and Standards Review Council. He is certified as a NETA Level IV Test Technician.
29
Transformers Handbook
ABNORMAL WEATHER CONDITIONS NETA World, Fall 2011 Issue By Kyle Springinatic, Magna Electric Corp.
In Canada and countries with similar climates, winter can be bitterly cold with heavy snowstorms along with ice, freezing rain, and temperatures almost always below zero degrees Celsius. These conditions, most notably temperatures, pose a big challenge for the electrical industry personnel that have to work outdoors. Interpreting outdoor electrical equipment test data and results requires a lot of preparation and analysis. In this article, a comparison of results on a 3.0 MVA, 13.8 to 0.6/0.347 kV transformer will be demonstrated in two different atmospheric conditions. The first scenario is testing at an outdoor temperature of -10ºC. The second scenario is performing the identical tests just moments apart indoors at a temperature of 20ºC. These tests were accomplished by placing the transformer outside our shop on March 13, 2011, when the ambient temperature was -19 degrees C and the wind chill was -28. Test results were obtained during the early morning hours and the actual transformer temperature was approximately – 10ºC as the previous day was around 0ºC.
Photo 2: Transformer Testing in Winter Conditions One of the most challenging feats is performing transformer work. This is particularly true when transformer assembly and vacuum filling are required. Vacuum filling works under the pretense that moisture will be flashed off under low pressure, but that will not work when the moisture is in a solid state (yes, that is ice). Normally the transformer will need to be completely covered with insulated tarps, and heat must be applied to make the vacuum process effective.
Photo 1: Transformer Testing in Winter Conditions
WINTER PROJECT CHALLENGES Electrical power system testing and maintenance has a number of challenges when working in extreme cold weather conditions. While large amounts of snow create problems, low temperatures have a huge effect on insulating mediums like SF6 gas and insulating oil as well as the test results associated with the equipment.
Photo 3: Oil Heating Process for Vacuum Filling
30
Transformers Handbook
Handling transformer oil is a challenge as well due to the viscosity of the oil becoming so low that the oil cannot be moved. The oil actually looks more like thick maple syrup. In these cases heated tankers are required to warm the oil to the point where transferring it becomes possible. If the oil is already in the transformer tank, the radiators can be shut off and the oil circulated through heaters to bring the transformer up to temperature for testing.
Table 1-2: High Side Winding Resistance Correction Factors
Most test equipment does not function properly at extremely low temperatures. Test equipment is often required to be set up in the warm vehicle and the test leads run out through the window. It is important to understand why some testing should not be performed, nor is it recommended when the temperature reaches below freezing point, unless certain heaters and insulated tarps with support structure can be provided to help keep heat in and around apparatus. For example, if a company were to test a transformer in -40ºC temperature, how accurate will the test results be? Are the powerfactor results going to capture all the moisture present in the oil, windings, and insulation? Is the test set screen going to freeze up? Are the results going to accurately compare with summer test records? Can the drain valve be accessed to take an oil sample? These are just some of the questions you will have to ask yourself before maintenance is performed on outdoor transformers and a service report is developed.
Table 1-3: Low Side Winding Resistance Correction Factors
INSULATION RESISTANCE Looking at the table from the ANSI NETA MTS-2011, it can be seen that at 20°C the temperature correction factor equals one. For every 10°C increase in temperature the correction factor approximately doubles and vice versa for decreasing temperature by 10°C. Table 1: Insulation-Resistance Correction Factors (20ºC) NETA Table 100.14.1
WINDING RESISTANCE Temperature has a direct proportional affect to the resistance of a conductor. For the operating range in temperature of a transformer, the relationship between resistance and temperature is a linear relationship. There are a few different formulas and coefficients available for calculating the resistance of copper or aluminum conductors, but this article will only focus on the inferred absolute temperature method as follows: Inferred Absolute Temperature (Ti) Formula:
Where: |T1|= inferred absolute temperature of conductor in Table 1-1 T2= measured ambient temperature R1= measured resistance T3= temperature to correct resistance value to R2= calculated corrected resistance Table 1-1: Inferred Absolute Temperatures (Ti)
Having the correct conversion factors will in fact give an accurate reading to 20°C for analyzing the test data as shown in Table 1-2 and 1-3. If no conversion factors were used for the winding resistance, results would not give a correct interpretation on the integrity of the transformer.
When performing a polarization index test on the transformer, results revealed a significant change in data for -10°C verses 20°C as shown in illustration 1 and illustration 2. The polarization index value with energizing the primary winding at 5 kV and measuring to the grounded secondary winding equaled 2.509 @ -10°C and 1.986 @ 20°C (23.3% difference). With the same test, but energizing the secondary winding at 500 volts and measuring to the grounded primary winding, PI results were calculated as 2.609 @ -10°C and 2.171 @ 20°C (18.3% difference).
31
Transformers Handbook Table 1-3: Outside -10ºC Doble Overall Tests
Table 1-4: Inside 20ºC Doble Overall Tests Illustration 1: 5000 Volt Primary to Secondary and Ground PI Test
OIL SAMPLING
Illustration 2: 1000 Volt Secondary to Primary and Ground PI Test
Gathering an oil sample from the top and bottom drain valves at below operating temperatures will give the greatest insight on the oil quality. As the temperature decreases closer to freezing point, the moisture present in the oil will escape, thus affecting high voltage testing. When the moisture is becoming extracted from the oil, it will sit closer to the bottom of the transformer tank.
POWER-FACTOR TESTING Power-factor testing can provide the most helpful and accurate results when it comes to transformer testing. Having previous data stored on the Doble history database allows one to compare results from past and interpret the stability of the transformer. But what if the stored test results differ in values? Table 1-3 and 1-4, show how the same transformer can provide different results at extreme temperature changes.
Photo 4: Power-Factor Testing Preparation
32
Transformers Handbook
The fact that the transformer tested poorly outside and good inside shows how crucial it is to consider the entire transformer’s temperature during testing. By placing a higher voltage on the windings, more results are revealed, but testing at a nonoperating, freezing temperature will not give acceptable data as clearly shown
RECOMMENDATIONS Move to Florida! There are many challenges involved with winter work especially when dealing with transformers and transformer oil. Special precautions and extra effort are required to get the equipment up to temperature so certain tasks can be done. It can be seen how such a drastic change in results are affected by temperature. Therefore, having an accurate test sheet temperature correction-factor database is crucial in order to have comparable results from season to season. In today’s world, digital test sets perform the majority of the testing and should, therefore, be kept in a warm environment where results can be accurately processed. If need be, bring the test set inside a vehicle or indoors and run the test leads outside to the equipment under test. When tarps and heaters are used to heat the transformer, ensure that all proper clearances are kept around bushing and test connections. Having scaffolding or any support structure too close to the bushings will also pose a threat to accurate test results. Kyle Springinatic is a NETA Level II technician that has been working with Magna Electric for four years in the oil and gas, potash, steel and generation industries.
33
Transformers Handbook
IMPORTANCE OF ANALYZING EXCITATION TEST RESULTS NETA World, Fall 2011 Issue by Keith Hill, Doble Engineering Company
Often times an indication of a problem is overlooked by testing personnel. Fortunately for the owner of this transformer, the technician correctly identified a major problem when performing acceptance testing of a new transformer. Proper identification of a problem with abnormal excitation current tests prevented this transformer from being placed into service which would have resulted in a failure upon energizing. The technicians from the testing company performed the standard acceptance tests that included: transformer overall power-factor tests, exciting current tests on all five deenergized tap-changer (DETC) positions, low-voltage transformer turns ratio (TTR) tests on all five DETC positions, and winding- resistance tests for both the primary and secondary windings. The overall power-factor, TTR, and winding-resistance results were all considered to be acceptable by the technicians performing the tests. The technicians correctly identified that the exciting current test results did not conform to the two high and one low current that is normally expected and notified plant personnel about a possible problem. Exciting current tests are performed in an attempt to identify an abnormal condition with the core or coil. Exciting current tests are often affected by a magnetized core. A magnetized core may be the result of performing dc winding resistance tests. For a three-legged core transformer, one usually expects to have two high currents and one low current with the middle winding having the lowest exciting current, although there are exceptions. When exciting current tests have a low-medium-high pattern, it is suspected that the core is magnetized. When this low-medium-high pattern is received, it is often recommended to demagnetize the transformer. Often the technician will assume that the core is magnetized and will not investigate the odd exciting current patterns. It is fortunate that the technicians who performed acceptance testing of this transformer identified the incorrect excitation current pattern and followed up on the problem. The exciting current test is a single-phase test that was introduced in North America as a diagnostic tool in 1967 and today is part of the standard tests in the field. It is primarily a test of the magnetic circuit of a transformer. Since that time, the exciting current test’s diagnostic capabilities have proven the ability to identify a range of problems. These include defects in the magnetic core structure such as shorted laminations or fundamental changes in the iron characteristics, failures in the turn-toturn insulation, or problems
in the tap-changing device. These conditions result in a change of the effective reluctance of the magnetic circuit which consequently affects the required current necessary to produce the flux in the core, or in other words, the exciting current measurement. While some electrical field-tests complement others in their ability to uncover similar types of problems and, therefore, lend themselves well as sanity checks, the exciting current test largely stands alone in its diagnostic capabilities. For this reason, most companies consider the test an essential one in the basic suite of tests performed on a transformer. While a low-voltage, turns-ratio test will detect complete failures in the turn-to-turn insulation, it is not nearly as sensitive as the exciting current test in detecting a strand-to-strand fault. The exciting currents measured by the testing company are shown in Table 1. Exciting Current Tests
ATTR test was performed on all five of the DETC positions using a low-voltage, electronic type instrument. All of the TTR test results were determined to be acceptable by the technician performing the tests. The manufacturer of the transformer was contacted by the owner and the data was reviewed by both parties. The manufacturer provided a field service engineer to investigate the problem, and an attempt was made to demagnetize the transformer following the demagnetizing procedure recommended by Doble Engineering. Attempts to demagnetize the transformer by field service personnel were unsuccessful as the currents did not change from the highmedium-low pattern. The H2 – H3 phase continued to have the high current (over four times higher) when compared to the other outside winding H3 – H1. At this point, Doble Engineering was contacted by the manufacturer to review the test data and to provide recommendations for additional diagnostic tests. After discussing the results, factory personnel wanted personnel from Doble to perform testing that would include power factor, exciting current, and sweep frequency response analysis (SFRA). The manufacturer also specified for Doble to attempt to demagnetize the transformer. As in the acceptance tests, all of the overall power-factor test results performed during the follow-up investigation were acceptable and matched prior test results.
34 Table 2 records the exciting current test results attained by Doble personnel before the demagnetizing procedure was performed.
Transformers Handbook Doble Transformer Turns Ratio
Exciting Current Tests before Demagnetization
The SFRA test was performed on this transformer in an attempt to identify the problem. The SFRA is a technique that has gained popularity internationally over the last ten years and is experiencing rapid growth and application in North America. Attempts made to demagnetize the transformer did not result in changes to the pattern or magnitude of the excitation currents. A problem with the core or windings was suspected. Table 3 contains the exciting current test results obtained after the demagnetizing procedure. Exciting Current Tests after Demagnetization
There is a direct relationship between the geometric configuration of the winding and core and the series and parallel impedance network of inductance, capacitance, and resistance. This network can be identified by its frequency-dependent transfer function. Frequency response analysis testing by the sweep frequency response method uses network analysis tools to determine the transfer function. Changes in the geometric configuration alter the impedance network and, in turn, alter the transfer function. This enables a wide range of failure modes to be identified. Interpretation of SFRA test results relies, in part, on comparison between phases and against previous test results. Commonality between transformers of the same design is also expected.
Test 6: Performed on Tap 5 after Demagnetizing of the Transformer was Attempted. Test 7: Performed after Demagnetization was Performed on H3 – H1. Test 8: Performed on Tap 5 with Shorter Intervals of DC Current Applied. It is noted that the H2-H3 phase continues to have current values four times higher than the H3-H1 phase. Since demagnetizing the core did not change the excitation test results, some other problem is assumed to be involved with the core or windings. One test that is recommended as part of the standard test procedure is the TTR. Turns ratio tests are particularly useful if there is a suspected open or short circuit. The turns ratio tolerance should be within the prescribed IEEE C57 guidelines of +/- 0.5 % based on the nameplate stated voltages for all windings. As part of the investigation, a TTR test was performed using the TTR capacitor. Using the capacitor in place of the standard TTR test set allows a higher test voltage, up to 10 kV, to be applied to the primary winding. Most TTR test sets are limited to less than 100 volts which greatly reduces the voltage on the secondary windings. Abnormalities were observed when attempting to energize the H2-H3 winding that limited the test potential for that phase. With 10 kV applied, test results were attained for phases H3 – H1 and for H1 – H2; however, when the test voltage was applied to H2 – H3, the test set would trip out on overcurrent. The test voltage applied to H2 – H3 had to be reduced to 2 kV before a ratio could be attained as the test set would trip out at 2.6 kV. It should be noted that all of the TTR results were acceptable at 2 kV. Using the standard, low-voltage, TTR test set would not have revealed a problem with the windings of this transformer.
SFRA – HV Open Circuit Tests H3 – H2 Appears to be Abnormal
SFRA – HV Tests with LV Winding Short CircuitedWindings Appear to be Normal
35
Transformers Handbook
with the magnetic circuit of this transformer. It was determined by the customer that the transformer would not be accepted and would be returned to the factory for inspection and repair.
FACTORY INSPECTION AND TESTING Diagnostic tests performed in the field revealed a possible problem with the windings. The transformer was returned to the factory for further inspection and testing. The following tests were scheduled to be performed: 1. Preliminary tests (ratio test, dc insulation, resistance) 2. Exciting current tests SFRA -LV Open Circuit Tests X3 – X0 Appears to be Abnormal and is the Same Phase as H3 – H2 The SFRA tests are actually a series of many tests over a band of frequencies from 20 hertz to 2 mega-hertz. The SFRA test results can be referred to as traces that are shown on a graph. The x-axis of the graph is the test frequency and the y-axis is the magnitude in decibels. These traces show the ratio of the output voltage to the input voltage of the transformer circuit under test at each of the frequencies. It has been shown that these traces are a signature that is related to the distributed resistance, inductance, and capacitance (RLC) of the components within the transformer. They should follow certain general shapes and favorable comparisons should exist among the phases of a transformer with previous test results and among transformers of identical design. The first, or benchmark, traces also provide a valuable tool to identify winding movement in the future. The SFRA test results for this transformer are shown in Figures 1 through 3. Figure 1 shows the results of the open circuit scan performed on the high voltage winding. The H1-H3 phase and H2-H1 phase exhibit expected pattern for this configuration of windings. H3-H2 phase reveals a deviation in the low frequency range which indicates irregularity with the transformer’s magnetic circuit. The SFRA traces in Figure 2 show the tests when highvoltage winding is energized with the low-voltage winding short circuited. The traces are expected to exhibit a similar starting point and an expected trail-off, followed by the more complicated form above 20,000 hertz which is typical of the short-circuit tests. By shorting the lowvoltage winding, the effect of the core is removed. The waveforms in Figure 2 are typical for the short-circuit test.
3. No load losses tests (NLL ) 4. High-voltage impulse test 5. Low-voltage impulse test 6. Induced voltage test In the factory report, it was noted that a high exciting current was measured on phase 3, H2 – H3, as reported by the customer. On the NLL test, the losses measured were nearly three times the value when tested in the plant during the original routine tests. During the high- and low-voltage impulse tests, the neutral low voltage failed. At this point it was determined to stop the electrical tests and to carry out the investigation of the failure. The top cover of the transformer was removed and the core and coil assembly was removed from the tank. The frame and top yoke were removed, and no signs of failure were observed. It was noted that the low-voltage coils from phase 2 had possible overheating on the top section. The coil was removed from phase 3, and the conductor in the high-voltage winding was unwound layer by layer, with a careful examination of the condition of each layer. An initial evidence of arcing was detected in layer 16 between adjacent turns. Similar evidence of arcing was also detected at the first two turns on layer 11. The factory noted that all ANSI routine and temperature rise tests were performed. After the temperature- rise test, no other tests were performed on this unit. Low Voltage
Figure 3 plots the SFRA open-circuit test results for the lowvoltage winding. As was observed in the high-voltage winding open circuit (Figure 1), there is a deviation in the low frequency range of the X3-X0 trace confirming abnormalities with the magnetic circuit. Although the overall power-factor test results were within the recommended limits, the single-phase exciting-current tests combined with irregularities observed when performing the TTR and SFRA tests provides substantial evidence there is a problem
Phase 2 Layer 16
Figure 5: Low Voltage Phase 3
36
Transformers Handbook with the small blister was not detected by routine test. After the temperature rise test, the blister in the conductor developed an increased contact between adjacent conductors. This condition resulted in an increase in the damage and the fault current but remained at a moderate energy release insufficient to be detected during the temperature rise test. The final condition of the fault was not detected since no other tests were performed after the temperature rise test.
Layer 11
It should be noted that the factory took immediate corrective actions in their test process/laboratory and in the winding process to prevent recurrence of this problem. It was noted in the factory’s diagnostic report that some testing will be performed at the factory after the heat rise test.
CONCLUSION
Layer 16
This case history confirms the importance of the test technician investigating an odd exciting current pattern. Power-factor results should never be the only criteria used in determining the acceptance of a transformer as other test data may reveal a problem. If the test technician had not identified and investigated the odd exciting current pattern, this unit could have failed when placed into service. When an odd exciting current pattern is obtained, the tester should not take for granted that the core is magnetized, as this odd pattern may indicate a problem with the core or windings. It should also be noted that the low voltage TTR tests did not reveal a problem with the turn’s ratio on this transformer. Use of the TTR capacitor, at a higher test voltage, revealed a problem with the turns ratio when the voltage applied was above 2.6 kV. The TTR capacitor data, along with the SFRA test results, confirmed that there was a problem with this phase.
REFERENCES
High Voltage Transformer Tests Uncover Manufacturing Defect Not Detected in the Factory. Presented by Keith Hill at the April 2008 Annual International Conference of Doble Clients. The diagnosis of the failure suggested an issue with the conductors. On the first finding, the investigation results suggested that the damage on the windings was due to a lack of conductor insulation. On the second finding it was noted that the conductor has a low level of insulation. The fact that there were no other tests performed after the temperature rise test led factory personnel to the following conclusion: During the temperature rise test, and with the thermal expansion on the conductors, the incipient short circuit between adjacent turns was aggravated, causing the arcing observed and worsening the fault current which was not detected afterwards since no additional testing was performed after the temperature-rise test. Factory personnel determined that the failure of the unit was due to a small blister in the conductor insulating enamel. The conductor
Keith Hill has been employed at Doble Engineering since 2001. He currently works as a Principal Engineer in the Client Service Department and is secretary serving on the Arresters, Capacitors, Cables, and Accessories Committee. Before being employed by Doble, Keith had over twentyfive years of testing experience with the last eighteen years as the electrical supervisor of engineering services at Lyondell-Citgo Refining in Houston. Keith received his Bachelor of Science from the University of Houston with a major in power. Keith is a member of IEEE, a Level II thermographer, and is a former NETA Certified Technician.
Single and 3-Phase Ratiometers
99% Of All Equipment Sold is Still In Operation Today!
10A and 200A Contact Resistance
In 1997, Raytech demonstrated the durability of its original TR-SPY by throwing it across the room at the NETA New Product Forum. That exact unit, along with over 3,000 sold since, is still in operation today. Raytech stands behind its custom-made, highquality measuring and testing equipment developed and produced for the international power industry.
Winding Resistance with Core Demagnatization
Trouble-Free and Backed by our 5 Year Warranty! Toll free 888 484 3779 | Phone: 267 404 2676 | Fax: 267 404 2685 118 South 2nd St., Perkasie, PA, 18944
www.raytechusa.com
37
Transformers Handbook
MODERN METHODS IN CURRENT TRANSFORMER TESTING NETA World, Fall 2011 Issue by Peter Fong, OMICRON electronics Corp. USA
Different test devices and methods are used in the market to verify the performance of current transformers during development, production, installation and maintenance. This article describes an innovative solution to test current transformers at all lifecycle stages by using a revolutionary testing method called “the modeling concept.” Current transformers are used in electrical power systems for relaying and metering purposes. Depending on the application for which they are used, the current transformers are designed differently.
APPLICATIONS AREAS The current transformers for metering and protection applications work basically the same way – transforming high power primary signals to lower secondary values. However, while current transformers used for protection applications operate to well above the load current, the current transformers for metering purposes must go into saturation directly above the load current level to protect the connected meter.
Protection Current Transformers
Current transformers play an important role in the protection of electrical power systems. They provide the protection relay with a replication of the primary current so that it can operate according to its settings. The transformation of the current values from primary to secondary must be accurate during normal load conditions and especially during fault conditions on the primary side (when currents up to 30-times the nominal current can be expected).
Metering Current Transformers
Today, energy is supplied by many different sources including alternative energy sources like solar and wind power. To guarantee accurate billing in this competitive electricity market, additional metering points are necessary. It is, therefore, important to have the entire metering circuit calibrated, as the meter is only as accurate as the instrument transformers sourcing it. This makes the testing and calibration of current transformers up to the 0.15 accuracy class essential. However, on-site testing of CTs of the 0.15 accuracy class is particularly critical as disturbances from power lines can influence the measurement results.
TESTING OF CURRENT TRANSFORMERS Conventional testing methods apply a signal on one side and read the output signal on the other side.
Several ways of conventional testing are possible: 1. The traditional way of testing a current transformer is to apply a high current to the primary side and read the signals on the secondary side. By using different burdens or injecting overcurrents, various situations can be simulated and the signals on the secondary side can be measured and analyzed. However, this method is timeconsuming and requires a lot of equipment. Sometimes it is not even feasible as very high currents are required, e.g., for on-site testing of a bushing current transformer inside a power transformer or a shunt reactor. 2. Another common testing scenario for current transformers is injecting a defined test voltage on the secondary side and reading the reverse transformed value on the primary side. Unfortunately, using this scenario, some parameters like accuracy and knee point (excitation curve), can only be tested with limitations. This is due to the scenario’s restrictions in accuracy caused by the very low signals in use and the maximum voltage of approximately two kV which can be applied to the secondary side of current transformers. Other important parameters like the transient dimensioning factor, the accuracy limit factor, the safety factor, composite errors, time constancies, and many others cannot be tested at all. As both methods have limitations, OMICRON has developed an innovative method of testing CTs.
MODELING CONCEPT OMICRON developed a CT analyzer test device which uses a revolutionary testing concept. The concept of modeling a current transformer allows for a detailed view of the transformer’s design and its physical behavior. The test device builds up a model of the current transformer by using initial data, measured automatically during the test. Based on this model the test device is able to calculate parameters like the secondary terminal voltage, Vb,the accuracy limiting factor (ALF), and the safety factor (FS), and simulate the CT’s behavior under different burdens or with various primary currents. The analyzer measures the transformer’s copper and iron losses according to its equivalent circuit diagram. While copper losses are described as the winding resistance, RCT, iron losses are described as the eddy losses or eddy resistance Reddy, and hysteresis losses as hysteresis resistance RH. With this detailed information about the core’s total losses, the CT analyzer is capable of modeling the current transformer and calculating the current ratio error as well as the phase displacement for any primary current and secondary burden.
38 Therefore, all operating points described in the relevant standards for current transformers can be determined. The model also allows important parameters such as the residual magnetism, the saturated and unsaturated inductance, the symmetrical short-current factor (overcurrent factor) and even the transient dimensioning factor (according to the IEC 60044-6 standard for transient fault current calculations) to be assessed. Within seconds a test report, including an automatic assessment according to IEEE C57.13 or C57.13.6 (Standard for High Accuracy Instrument Transformers) is generated. The CT analyzer offers a very high testing accuracy of 0.05% (0.02% typical) for current ratio and 3 minutes of angle (1 min typical) for phase displacement.
Figure 1: Equivalent circuit diagram of a real current transformer
RESIDUAL MAGNETISM A new measurement function for the CT nalyzer allows current transformers to be tested for residual magnetism. Residual magnetism may occur if a current transformer is driven into saturation. This can happen as a consequence of high fault currents containing transient components, or direct currents applied to the current transformer during winding resistance tests or during a polarity check (wiring check). Depending on the level of remaining flux density, residual magnetism dramatically influences the functionality of a current transformer.
Transformers Handbook the current which caused the remanence. In a second step, the current transformer is demagnetized by reducing the voltage gradually to zero.
Figure 5 and 6: Demagnetization principle of iron cores The CT analyzer performs the residual magnetism measurements prior to the usual CT testing cycle as it automatically removes residual magnetism after testing. In order to determine the residual magnetism the CT analyzer drives the core into positive and negative saturation alternately until a stable symmetric hysteresis loop is reached. The CT analyzer then calculates the initial remanence condition to determine whether the core was affected by residual magnetism. The results are displayed as absolute values in voltage per second as well as in percent relative to the saturation flux (Ψs: defined in the IEC 60044-1) on the residual magnetism test card. Additionally, the remanence factor Kr is shown on the test card.
Figure 7: Test card of the CT analyzer showing the measurement results of a residual magnetism test The CT analyzer automatically demagnetizes the current transformer when the test is complete.
CONCLUSION
Figure 4: Hysteresis curve at the max. saturation point showing the possible area for residual magnetism Since remanence effects in protective current transformers are not predictable and barely recognizable during normal operation, these effects are even more critical. Unwanted operation of the differential protection may be caused. Protective relays also may show a failure to operate in case of real overcurrent as the current transformer’s signal is distorted due to the residual magnetism in the CT core. Once the current transformer is magnetized, a demagnetization process is necessary in order to remove residual magnetism. This can be achieved, e.g., by applying an ac current with similar strength as
After installation, current transformers are typically used for 30 years. In order to guarantee a reliable and safe operation over the life time of the CTs, a high level of quality during design phase, manufacturing process, and installation is essential. Therefore, several quality tests are performed from development to installation. After installation, CTs should be tested on a regular basis to ensure correct functioning over the entire life time. eter Fong received a BS in Electrical P Engineering from the University of British Columbia in 1988. He joined OMICRON in 2000, where he presently holds the position of Application Engineer. Prior to joining OMICRON, he worked for 12 years at BC Hydro and two years at a relay manufacturer in the US. Peter Fong is a Professional Engineer (APEGBC) and a member of IEEE.
39
Transformers Handbook
ADVANCED DIAGNOSTIC TESTING METHODS FOR TRANSFORMERS PowerTest 2012 by Charles Sweetser, OMICRON electronics Corp. USA
INTRODUCTION
INSULATION PROPERTIES
The electric power industry is always looking for best the approach to better determine the condition of power transformers. For decades the industry has relied on conventional off-line tests which depend on a single measurement at single frequency, constant voltage, or static mode. At times, only having conventional test data for review has led to an inconclusive analysis or condition assessment. Research in conjunction with modern measuring instruments has identified that additional valuable information exists if frequency, voltage, and other dynamic parameters are allowed to vary. From an engineering and maintenance perspective, these advanced diagnostic tests, which are just extensions of the conventional tests, provide new and critical information about the health of the power transformer.
Insulation systems consisting of cellulose and oil exhibit both polarization and conductivity phenomena. These two phenomena occur simultaneously, and superposition must be applied to discriminate their effects due to the combination of both cellulose and oil.
The comprehensive suite of basic or standard field tests widely applied today in transformer diagnostics, though careful selection, hierarchal value, and appropriate times of use, includes: • Dissolved Gas Analysis (DGA) • Oil Screen • Power Factor • Exciting Current • Turns/Voltage Ratio • DC Winding Resistance • Sweep Frequency Response Analysis (SFRA) • Leakage Reactance • Insulation Resistance • Partial Discharge (PD) • Thermography (IR) The focus of this paper is to investigate advanced variations of the traditional power factor measurement that is performed at rated frequency. Understanding insulation properties is essential in exacted in-depth diagnostic information. The advanced protocol takes advantage of frequency domain measurements (Dielectric Frequency Response – DFR) to identify polarization and conductivity properties of oil paper insulation systems. Of specific interest, is the interfacial polarization effect, which occurs at the interface boundaries between cellulose and oil. Particular emphasis will focus on dielectric behavior as a function of frequency at or near the fundamental power frequency.
Moisture, temperature, and aging by-products influence both polarization and conductivity domains, where moisture has the greatest influence. It should be noted that it is not possible to separate these components (polarization losses and conductive losses) at an arbitrary frequency (60 Hz) [7].
Polarization Losses In the frequency range in the neighborhood of 60 Hz, DC(0 Hz)to 10 kHz, two types of polarization losses exist, interfacial polarization (0.0003 Hz) and molecular polarization (10 kHz). When dissimilar materials, such as cellulose and oil are combined together, an interfacial polarization process materializes. Interfacial polarization is typical for non-homogeneous dielectrics with different permittivity or conductivity. Here space charge carriers such as ions accumulate at the interfaces, forming clouds with a dipole-like behavior [1]. The interfacial polarization is the resonance that occurs between the propagation speed and distance traveled of the space charge carriers as a function of the insulation geometry (ratio between oil, barriers and spacers). Interfacial polarization between cellulose and oil occurs at lower frequencies; 1 mHz for dry and cool insulation systems and 10 Hz for wet and hot insulation systems. In cellulose and oil insulation systems the individual molecular structures produce polarization losses. These molecular losses can peak around 10 kHz. At or near 60 Hz, these losses cause the power factor values to slightly increase and decrease proportionally with frequency for healthy insulation systems. Figure 1a illustrates this behavior in the 10 Hz to 1 kHz range.
Conductive Losses Both cellulose and oil exhibit conductive losses, however oil is unique in the fact that by itself it solely produces conductive losses. Figure 1b illustrates contact conductive losses in oil. While conductive losses are seen in both cellulose and oil, it can be affirmed that the losses associated with the oil dominate. However, at very low frequencies occurring below the interfacial polarization range the conductive properties of oil are minimized as compared to cellulose.
40
Figure 1a: Losses in Cellulose
Transformers Handbook
Figure 1b: Losses in Oil
Moisture and Temperature It is worthy to mention the dangerous effects of moisture and high temperatures in insulation systems. Together they negatively affect the performance and life expectancy of insulation systems. Moisture and/or high temperatures contribute to the following: • Decrease in dielectric withstand • Accelerated cellulose aging • Bubble evolution
The first instrument to measure an unknown capacitance and its dissipation factor was the Schering Bridge. This is basically a fourarm alternating-current (AC) bridge circuit whose measurement depends on balancing the loads on its arms. The bridge required the use of a higher voltage, a few kV. For practical reasons, the frequency was mostly limited to power frequency. These historical conjunctures found its way into standards and field test practices, where a test voltage of typically 10 kV and a limited frequency range close to power frequency are used [1]. Industry standards give various limits for power factor. For example, IEEE Std. 62-1995 states that in the case of new oil-filled transformers and reactors, the power factor measurements should not exceed 0.50%. It further recommends that it is acceptable for older power transformers to have power factors between 0.50% and 1.00%; however, power factors greater than 1.00% should be investigated.
Dielectric Frequency Response (DFR)
Moisture enables acids to serve as a catalyst to assist the breakdown process. As the polymer chains of the cellulose are broken down into smaller chains, the cellulose over time becomes brittle. This brittleness can be measured by the Degree of Polymerization (DP), where new cellulose has a DP of 1200 and a DP of 200 indicates “end-of-life.”
Dielectric diagnostic methods deduce moisture in paper or pressboard from dielectric properties like re-turn voltage, polarization and depolarization currents and dissipation factor. Primary motivations for the development of dielectric response methods were the lack of methods for on-site moisture assessment in power transformers and the disappointing results of the hitherto used conventional equilibrium approach.
MEASUREMENTS
Recovery Voltage Method (RVM)
Traditionally, basic measurements have been performed on insulation systems to estimate the condition or to identify an incipient failure mode. These methods range from oil and material analysis to Power Factor measurements.
In this method, a voltmeter determines the recovery voltage after charging the insulation with a DC voltage. By subsequent relaxation and repeated charging for varied times the so called “polarization spectrum” can be created [2]. This technique is outdated since its interpretation scheme appeared to be unable for compensating the interfacial polarization effect and oil properties [3]. In recent years, the Recovery Voltage Method has lost popularity to improved dielectric response methods, such Polarization and Depolarization Currents PDC [4] and the Frequency Domain Spectroscopy FDS [5].
Power Factor at Power Frequency The Power Factor at one single frequency point has been used for decades to determine the integrity and condition of an insulation system. Figure 2 illustrates the equivalent circuit for losses in insulation materials and the corresponding vector diagram. Any solid or liquid insulation can be modeled by a capacitance Cp, representing the “ideal” behavior of insulation, and a resistor Rp, representing the electrical losses. The Power Factor (cos ) indicates the quality of insulation materials by the ratio of resistive current IR to total current IT [1].
Figure 2: Equivalent circuit for insulation materials and corresponding vector diagram
Polarization and Depolarization Currents (PDC) A time domain current measurement records the charging and discharging currents of the insulation. They are usually called Polarization and Depolarization Currents PDC. Figure 3 depicts the shape and common interpretation of a PDC measurement.
Figure 3: PDC Wave Shape and Interpretation
41
Transformers Handbook Frequency Domain Spectroscopy FDS The Frequency Domain Spectroscopy test measures and models the properties of insulation systems across a wide frequency range, e.g. 1000 Hz to 0.1 mHz. This frequency span over 7 decades enables for discrimination between the effects of polarization losses, conductive losses, and aging by-products within the overall insulation system [1]. Techniques that provide power factor measurements across a frequency band better help discriminate the characteristics of moisture, aging, temperature, contamination, oil conductivity, and the influence of external environmental conditions. Analysis algorithms are then applied to determine moisture, conductivity, and insulation geometry. Figure 4 displays the dielectric behavior of paper, pressboard, and oil having 1.0 % moisture content at 20°C. The frequency range of 10 Hz - 1 kHz is dominated by the cellulose insulation, however also the measurement cables and the connection technique influence this region. Oil conductivity causes the steep slope at 0.01 Hz – 1 Hz. Dissolved conductive aging by-products increase the oil conductivity and thus influence this area. The interfacial polarization (insulation geometry, ratio of oil to pressboard) determines the local maximum or “hump” in the 0.003 Hz range. The higher the ratio of oil to pressboard, the more dominating is this effect. Finally, the moisture effects within the cellulose appear again at the frequencies below 0.5 mHz [1].
Figure 5: Combined PDC and FDS Measurement Using Transformation the combining of time and frequency domain measurements. A transformation is applied to the time domain measurement and the final result is plotted as a function of frequency.
Power Factor Tip-Up The Power Factor Tip-Up method monitors the behavior of insulation as a function of test voltage. The test voltage is generally increased at predetermined levels and the power factor is recorded. Healthy insulation systems in transformers and bushings should not produce the “Tip-Up effect”, whereby the percent power factor increases with an increase in voltage. Sensitivity to Tip-Up can be caused by aging, localized defects that result in partial discharges, and defective connections in series with a given insulation path.
Figure 4: Dielectric Behavior for Cellulose and Oil as a Function of Frequency
Combining Time and Frequency Domain Measurements Combining the polarization current measurement method in time domain with the frequency domain spectroscopy can significantly reduce the testing time compared to existing techniques. Essentially, time domain measurements can be accomplished in a short time but are limited to low frequencies. In contrast, frequency domain measurements are feasible for high frequencies but take a very long time to complete at low frequencies. Figure 5 illustrates
For practical purposes the “value” of Tip-Up is the difference between the 10 kV Power Factor and the 2 kV Power Factor for insulation systems rated at 15 kV and above. It is not the terminal voltage level that causes Tip-Up, but the localized field strength within insulation systems. The field distribution is dependent on the physical geometry of the test specimen. The electric field stress across a narrow gap in the insulation will be much higher than that across larger gaps. The gap size observation indicates that Tip-Up is a stronger diagnostic for bushing insulation systems as compared to large power transformers. Figure 6a shows Tip-Up tests on 2 similar bushings. These are 500 kV 1975 Westinghouse Type O bushings. Figure 6b is a follow-up frequency sweep test that was also used to rule out moisture.
42
Figure 6a: Power Factor Tip-Up
Figure 6b: Variable Frequency Power Factor
Transformers Handbook
Figure 7: Superposition of Cellulose and Oil
Figure 8: Polarization and Conductive Losses Near 60 Hz
The Tip-Up measurement in red is voltage sensitive, and the measurement begins to noticeably Tip-Up at 6 kV. The way transformer insulation is tested greatly depends on application purpose, design and configuration. Various transformer test protocols exist. Table 1, shown below, lists a few common types. Table 1: Main Insulation Components
Figure 9 illustrates typical 2-winding transformer measurements, which include CH, CL, CHL.
With regards to moisture, the diagnostics should focus on the inter-winding insulation (CHL, CHT, CLT, and CAutoT). The interwinding insulation isolates the bulk cellulose. The bulk cellulose is influenced by both conductive and polarization losses near 60 Hz; however this measurement is very sensitive to the conductive losses in this range due to the conductivity of the oil. Figure 7 illustrates the superposition effects of the oil and cellulose. Figure 8 shows the conductive influence of the oil in the 60 Hz range.
Figure 9: Typical 2-Winding Transformer Measurements (CH, CL, CHL)
43
Transformers Handbook Figure 10 shows inter-winding measurements from 4 different transformers with various levels of moisture present. The 60 Hz power factor measurements were 0.23%, 0.46%, 0.68%, and 2.16% at 20°C, see Table 2. The Extreme and Wet units measured 3.7 % and 4.6% moisture content by weight, respectively.
CONCLUSION Advanced diagnostic methods for analyzing moisture and the dielectric properties of power transformers and bushings are useful and pertinent tools with which to determine the insulation health of the subject apparatus. As an asset manager reviewing the life expectancy of the equipment or a power system operations manager responsible for determining the loading capabilities of the equipment, it is important to know the conditions and degree of moisture in transformers and bushings. In summary, the following points can be concluded from this paper: 1. Dielectric diagnostic methods deduce moisture in the solid insulation from dielectric properties like polarization and depolarization currents and dissipation factor vs. frequency [6].
Figure 10: Inter-winding Measurements with Various Levels of Moisture Present Table 2: Power Factor and Moisture Measurements
2. Oil conductivity has a significant impact on the dielectric response of transformers, and therefore this must be compensated for when attempting to determine the moisture content of the solid insulation. 3. When performing a measurement at an arbitrary frequency (60Hz) it is not possible to separate the resistive (conduction losses) and the dielectric (polarization) losses [7]. 4. Moisture predominately resides in the paper insulation, in lieu of the oil. 5. The Dielectric Frequency Response method provides a comprehensive approach to determining the moisture content in the solid insulation.
REFERENCES Figure 11, shown below, illustrates the CHL power factor behavior from two similar transformers. The 60 Hz power factors are identical (0.22%); however the overall responses are different. These results would be an indication that T2 has a slightly higher moisture content.
[1] M. Koch, M. Krueger, M. Puetter. “Advanced Insulation Diagnostic by Dielectric Spectroscopy.” TechCon Asia–Pacific, Sydney 2009; [2] E. Nemeth. “Measuring the Voltage Response, a Diagnostic Test Method of Insulation.” Proceedings of the VII International Symposium on High Voltage Engineering, ISH, Dresden, 1991; [3] M. Koch, M. Kruger, S. Tenbohlen. “Comparing Various Moisture Determination Methods for Power Transformers.” South Africa Regional Conference, CIGRE 2009; [4] V.D. Houhanessian. “Measurement and Analysis of Dielectric Response in Oil-Paper Insulation Systems.” Ph.D. Dissertation, Swiss Federal Institute of Technology Zurich, ETHZ, 1998; [5] R. Niemanis, T.K. Saha, R. Eriksson. “Determination of Moisture Content in Mass Impregnated Cable Insulation Using Low Frequency Dielectric Spectroscopy.” IEEE Power Engineering Society Summer Meetings, p 463-468, vol. 1, Seattle, USA, July 16-20, 2000; [6] M. Koch, M. Krüger. “Moisture Determination by Improved On-Site Diagnostics.” TechCon Asia Pacific, Sydney 2008;
Figure 11: Typical 2-Winding Transformer Measurements from similar transformers at 20°C.
[7] S.M. Gubanski, P. Boss, G. Csepes, V. Der Houhanessian, J. Filippini, P. Guuinic, U. Gafvert, V. Karius, J. Lapworth, G. Urbani, P. Werelius, W. Zaengl. “Dielectric Response Methods for Diagnostic of Power Transformers.” Preport of the TF D1.01.09 , CIGRE 2002.
44
Transformers Handbook
ANCILLARY DEVICES NEED TESTING TOO PowerTest 2012 by Rick Youngblood, Doble Engineering
It is common knowledge that transformer cost comprises anywhere from 40-60% of the price of a substation. The cost has spiraled out of control, up 40% from last year. These price increases have dried up the inventory of the used market and new transformers are averaging 50-56 weeks from order to arrival. All rewind shops are swamped and their time lines are growing as well. Unfortunately, the majority of the U.S. transformer population is also at the end of the baby boom era and requires special care and testing if they are to continue to serve until the market can catch up. In some of the more progressive industries and utilities, transformer testing is nothing more than a walk around to look for leaks, nitrogen and oil levels, LTC count, and the temperature recorded by the hot spot and top oil gages. Some company maintenance and test personnel have implemented DGA testing but many still have no clue of its value. The companies that do regularly test transformers are many times still guilty of only testing what is inside the tank and totally overlook many of the obvious other transformer failure producing indicators on the outside. To truly test a transformer 100%, all of
Picture 1: Motor mounted capacitor
the failure modes must be known and tested for on a regular basis. All failure modes can be classified into one of the three following categories: mechanical, electrical and dielectric. Each of these categories should be further divided into internal and external testing. The last two divisions are what separate mediocre from the complete testing programs.
EXTERNAL FAILURE MODES Mechanical failures are typically broken into LTC drive systems and cooling. It is imperative the LTC make a full tap change at a speed where internal arcing damage is minimized. Items such as weak motor starting capacitors (Pictures 1 and 2) and low source voltage will cause the motor to labor; pull abnormally high currents, and eventually burn up if not protected by a safety of some sort. Motor voltage should not drop more than 10% during tap change from 1 L to 1 R. Low voltage means high current and overheating. Bad source wiring or corroded connections to the LTC can also be a culprit of low voltage.
Required Torque = Source Voltage X Current Voltage Down = Current Up
Picture 2: Externally mounted capacitor
45
Transformers Handbook Stiff rusty chains (Picture 3), weak drive springs, dry gear boxes and poor shaft alignment all contribute to tap changer and transformer failure and have nothing to do with the internal workings of LTC or windings. Many transformer failures can be attributed to the failure of the dynamic braking system that stops the LTC on tap rather than partially on tap as can be seen below in (Picture 4.)
Dry “All Thread” 33 cam switch activators and rusty bearings cause timing errors, out of sequence stepping or failure in the end of stroke limit switches. Picture 3: Rusty chains on a Federal Pacific TC-525
True maintenance of these items does not mean spraying them with WD-40 or any other solvent based penatrent. The only correct solution is to disassemble clean and repack the bearing or gear box with compatible grease or replace the defective parts. Don’t Be A Maintenance man in a can.”
COOLING Cooling is essential for long transformer life. Most transformers are designed for 55C or 65C rise. Using newer insulations such as Nomex®, temperatures of 95C and higher can be achieved. These temperatures can only be maintained if the transformer operating conditions do not exceed the design limitations.
Picture 4: Contact failure due to faulty drive mechanism on a 550B
Unfortunately in today’s operating environment, most end users are pushing loads well past nameplate design limitations resulting in increased winding temperatures. These temperatures are primarily due to increased losses such as I2R. Increased heating plays a major effect on the degradation of insulation quality and drastically diminishes its life expectancy. Here the standard 10 rule of thumb still applies for insulation half life.
46
Transformers Handbook
Transformers are either self cooled through natural oil convection and rated ONAN (Picture 5) or fan cooled and rated ONAF (Pictures 6 and 7). In most extreme cases, forced oil or forced oil over water cooling with a rating of OFAF or OFWF (Picture 11) are used. In each case, it is extremely important that proper temperature transfer takes place. The design of the transformer relies on a specific heat transfer between the windings, oil and the radiator or cooler for heat extraction. Any increase in heat generation or any heat transfer reduction results in higher winding temperatures and shorter insulation life. Additionally, the dielectric fluid is degraded and will be covered in a later section.
Picture 6: ONAF cooling provided by fans used to increase using natural oil convection (bottom mount up draft)
Picture 7: ONAF cooling provide by fans used to increase cooling using natural oil convection. (Side mount)
Picture 5: ONAN naturally cooled through oil convection cooling no external fans
Bottom mount fans blow air across the total length of the cooler or radiator but have higher motor failure due to water entrance around the shaft seal. The use of totally enclosed, non vented motors with high quality shaft seals do however increase motor life. Inspection of these motors should be made monthly. Side mounted fans have a longer life expectancy but tend to blow only across the section of the cooler or radiator where placed. Side mounted fans are also very susceptible to prevalent wind direction which can help or defeat the air movement across the heat transfer surface. Open frame motors are not recommended in any case due to higher failure rates due to environmental considerations.
47
Transformers Handbook Typically one fan failure does not cause serious problems, but does result in an overall temperature increase for the transformer especially if overloaded to begin with as can be seen in infrared picture 8. Fans typically fail in batches. They are manufactured at the same time and operate in the same environment. Observation of one failure should be an indicator that others may be ready to fail as well leaving the transformer in danger of over temp.
Picture 8 Picture 9 is loss of cooling in some radiators due to concrete pad settling tilting the transformer. This can in some cases be corrected by increasing the oil level in the main tank to a level permitting oil flow through the radiators. Care should be taken to not overfill and create a problem due to oil expansion that takes place during overheating.
Picture 9 In picture 10 all of the oil valves to the radiators are higher than the oil preventing oil circulation. Low oil level can be a result of leaks or failure to be adequately filled when last serviced. One last issue causing the same consequence happens if the upper butterfly valves to the radiators are turned off during maintenance and not turned back on preventing oil flow. A simple thermography test will reveal this life robbing problem.
Picture 10
uses a small vane gage located in the piping indicating pump ON or OFF activity. Flow indicators are not always accurate. Many times 48 Handbook during maintenance a gage isTransformers found to be stuck and not truly indicate flow. A simple test can be Forced oil pumping systems FOA/ FOW (Picture 11) provide performed by turning the pump off and look at for high flow rates through radiators and the transformer providing the indicators to determine if they read correctly. maximum heat transfer. Pumps, themselves their setuses of afailure Pump flow rate is hardcreate to measure and own typically small #11 modes in located a transformer; to pump tightON tolerances vane gage in the piping built indicating or OFF acindicators are not always accurate. Many timesAs durdotivity. notFlow tolerate loose bearings or bushings. ing maintenance a gage is found to be stuck and not truly indicate they age, bearings, bushings or thrust washers flow. A simple test can be performed by turning the pump off and wear and can cause impeller drag on the pump look at the indicators to determine if they read correctly. Pumps, housings 12set &of13). large themselves (Pictures create their own failureThis modescauses in a transformer; deposits oftolerances metal filings to beloose deposited the built to tight do not tolerate bearings orin bushings. As they age, bearings, bushings thrust washerscauses wear and can transformer windings andoreventually cause impeller drag on the pump housings (Pictures 12 and 13). insulation failure as they vibrate at operating This causes large deposits of metal filings to be deposited in the frequency and wear in. transformer windings and eventually causes insulation failure as Ultrasonic for bearing wear is aninspecthey vibrate atinspection operating frequency and wear in. Ultrasonic excellent testwear andiscan be performed tion for bearing an excellent test and canat be anytime performed atas Picture 11 anytime as long as the pump is running as shown below. long as the pump is running as shown below. Stages of thrust washer wear New/Failed
#12
Picture 12: Stages of thrust washer wear New/Failed
Ball bearing failure leading to transformer failure
#13
ELECTRICAL TESTING Electrical testing is normally thought of as tests such as TTR, insulation resistance, core ground and power factor. All are in tank tests! External testing is just as important to maintain transformer health and prevent unwanted failures. As previously discussed, transformer temperature is extremely important. Most end users take for granted the Hot Spot and Top Oil gages to be accurate and their alarms functional. Regular calibration of these indicators should be performed and many can be done without removing the transformer from service.
Picture 13: Ball bearing failure leading to transformer failure
(#14) “Jofra” Hot Well Probe Calibrator Transformers Handbook
(#15) Standard winding temperature gage made by “Orto”.
Be sure to check on the integrity of the plug and cable, a known trouble area as seen below in picture (#16)
49
Picture 16
Be sure(seen to checkleft) on thecan integrity of the plug and cable, a known Oil level gages become stuck in one trouble area as seen below in picture (Picture16) position after many years without movement. Most are magnetically coupled through the tank wall and can fail without notice. Oil leaks and multiple oil samples can all Picture 14: “Jofa” Hot Well Probe Calibrator lead to low oil levels. Care should be taken to insure these The use of a temperature well calibrator, as seen in the picture gages work properly and if connected to alarms or trip 14., in combination with a continuity tester can both determine circuits, set and trip points but also determine if the micro switches used to provide the correct outputs. Magnetically sound alarms or trip the transformer actually work andcoupled trigger at gages can be removed without the loss of oil and the temperatures desired. Switch activation may mean the candifferbe tested using a continuity check and rotating the ence in tripping the transformer off safely or transformer failure. gage to indicate low oil level. (Picture 15.)
Picture 17 Oil level gages (seen above) can become stuck in one position after many years without movement. Most are magnetically coupled through the tank wall and can fail without notice. Oil leaks and multiple oil samples can all lead to low oil levels. Care should be taken to insure these gages work properly and if connected to alarms or trip circuits, provide the correct outputs. Magnetically coupled gages can be removed without the loss of oil and can be tested using a continuity check and rotating the gage to indicate low oil level. Picture 15: Standard winding temperature gage made by “Orto”.
BUSHINGS Bushing integrity is paramount. Bushings should be tested during transformer outages as per NETA specifications. Other tests such as thermography can be performed during non outage periods providing valuable information as to transformer health.
50
Transformers Handbook Overheating of the test tap as seen in Picture 20 can be caused by a poor connection in the grounding cap. Partial discharge or an open circuit can lead to bushing and transformer failure. Identified through thermography, this test can be performed at anytime while the unit is energized and can provide the important data to determine if a forced outage needs to occur to correct failure causing problems.
DIELECTRIC MAINTENANCE
Picture 18: Top connection overheating
Oil and insulation maintenance is paramount to transformer life expectancy. Paper insulation is designed to be pliable and give with fault current winding distortion. The addition of heat damages paper insulation irreversibly. Paper becomes brittle and no longer gives with winding distortion. Once the pliability of the paper is lost, the insulation will begin to crack under fault conditions providing a path for turn to turn shorts and eventual winding and transformer failure. Oil is designed to provide maximum cooling and insulating strength. Addition of water and oxygen decreases dielectric strength and begins acid formation. Loss of dielectric strength leads to partial discharge or flash over and again insulation failure. Dielectric testing is required to determine both insulating oil and paper health. Typical oil tests are Dissolved Gas Analysis Dielectric Breakdown, Power Factor, Acidity, IFT, Color, and Karl Fisher. Other tests such as Degree of Polymerization and Furnanic Compounds can be useful in determining the condition and remaining life of the insulation and should be done sparingly as the transformer ages or in cases of overloaded, overheated units. All can be done with the transformer in service.
CONCLUSIONS
Picture 19: Internal overheating due to overload High resistance on top connection to a bushing (Picture 18) can cause conductor failure and/or internal bushing pressurization and ultimately bushing failure. Complete overheating (Picture 19) occurs due to high resistance internal to the bushing or in many cases today, overloading of the bushing beyond design limits.
Transformer testing whether internal or external is paramount in providing the maximum life expectancy of our equipment whether new or one from our aging fleet. Only if all possible failure modes are addressed can we be certain to provide our customers with a level of certainty that we have done everything possible to insure the integrity of their transformers. There is nothing worse to a test technician than a call form a customer asking why their transformer failed only to find out an omitted test could have caught the problem and prevented the failure. It is the difference between a mediocre and an excellent testing program. Are you missing the test point?
Picture 20: Test Tap Overheating
NETA Accredited Companies Valid as of January 1, 2014
For NETA Accredited Company List Updates Visit www.netaworld.org
Ensuring Safety and Reliability Trust in a NETA Accredited Company to provide independent, third-party electrical testing to the highest standard, the ANSI/NETA Standards. NETA has been connecting engineers, architects, facility managers, and users of electrical power equipment and systems with NETA Accredited Companies since1972.
United StateS
Hampton Tedder Technical Services 3747 West Roanoke Ave. Phoenix, AZ 85009 (480) 967-7765 Fax:(480) 967-7762 www.hamptontedder.com
8
Southwest Energy Systems, LLC 14 2231 East Jones Ave., Suite A Phoenix, AZ 85040 (602) 438-7500 Fax: (602) 438-7501
[email protected] www.southwestenergysystems.com Robert Sheppard
9
Western Electrical Services, Inc. 5680 South 32nd St. Phoenix, AZ 85040 (602) 426-1667 Fax: (253) 891-1511
[email protected] www.westernelectricalservices.com Craig Archer
AlAbAmA 1
2
AMP Quality Energy Services, LLC 4220 West Schrimsher SW, Site W1 PO Box 526 Huntsville, AL 35804 (256) 513-8255
[email protected] Brian Rodgers Utility Service Corporation 4614 Commercial Dr. NW Huntsville, AL 35816-2201 (256) 837-8400 Fax: (256) 837-8403
[email protected] www.utilserv.com Alan D. Peterson
ArizonA 3
4
5
6
ABM Electrical Power Solutions 3602 East Southern Ave., Suite 1 & 2 Phoenix, AZ 85040 (602) 796-6583 www.abm.com Jeff Militello
13
7
ABM Electrical Power Solutions 720 S. Rochester Ave., Suite A Ontario, CA 91761 (951) 522-8855 Fax: (909) 937-6798 www.abm.com Ben Thomas
American Electrical Testing Co., Inc. 12566 W. Indianola Ave. Avondale, AZ 85392 (480) 383-9242 11 Apparatus Testing and Engineering
[email protected] 7083 Commerce Cir., Suite H www.aetco.us Pleasanton,CA 94588 Donald Madaglia (925) 454-1363 Fax: (925) 454-1499
[email protected] Electric Power Systems, Inc. www.apparatustesting.com 557 E. Juanita Ave., #4 Harold (Jerry) Carr Mesa, AZ 85204 (480) 633-1490 Fax: (480) 633-7092 12 Apparatus Testing and Engineering www.eps-international.com PO Box 984 Folsom, CA 95763-0984 Electrical Reliability Services (916) 853-6280 Fax: (916) 853-6258 1775 W. University Dr., Suite 128
[email protected] Tempe, AZ 85281 www.apparatustesting.com (480) 966-4568 Fax: (480) 966-4569 James Lawler www.electricalreliability.com
Electrical Reliability Services 5810 Van Allen Way Carlsbad, CA 92008 (760) 804-2972 www.electricalreliability.com
15
Electrical Reliability Services 6900 Koll Center Pkwy., Suite 415 Pleasanton, CA 94566 (925) 485-3400 Fax: (925) 485-3436 www.electricalreliability.com
16
Electrical Reliability Services 10606 Bloomfield Ave. Santa Fe Springs, CA 90670 (562) 236-9555 Fax: (562) 777-8914 www.electricalreliability.com
17
Hampton Tedder Technical Services 4571 State St. Montclair, CA 91763 (909) 628-1256 x214 Fax: (909) 628-6375
[email protected] www.hamptontedder.com Matt Tedder
18
Industrial Tests, Inc. 4021 Alvis Ct., Suite 1 Rocklin, CA 95677 (916) 296-1200 Fax: (916) 632-0300
[email protected] www.industrialtests.com Greg Poole
CAliforniA 10
Applied Engineering Concepts 1105 N. Allen Ave. Pasadena, CA 91104 (626) 398-3052 Fax: (626) 398-3053
[email protected] www.aec-us.com Michel Castonguay
For additional information on NETA visit netaworld.org
53
19
20
21
22
23
24
Pacific Power Testing, Inc. 27 14280 Doolittle Dr. San Leandro, CA 94577 (510) 351-8811 Fax: (510) 351-6655
[email protected] www.pacificpowertesting.com Steve Emmert 28
Power Systems Testing Co. 4688 W. Jennifer Ave., Suite 108 Fresno, CA 93722 (559) 275-2171 x15 Fax: (559) 275-6556
[email protected] www.powersystemstesting.com David Huffman
Magna IV Engineering 96 Inverness Dr. East, Unit R Englewood, CO 80112 (303) 799-1273 Fax: (303) 790-4816
[email protected] Aric Proskurniak Precision Testing Group 5475 Hwy. 86, Unit 1 Elizabeth, CO 80107 (303) 621-2776 Fax: (303) 621-2573
[email protected] Glenn Stuckey
ConneCtiCut
Power Systems Testing Co. 6736 Preston Ave., Suite E Livermore, CA 94551 (510) 783-5096 Fax: (510) 732-9287 www.powersystemstesting.com Power Systems Testing Co. 600 S. Grand Ave., Suite 113 Santa Ana, CA 92705-4152 (714) 542-6089 Fax: (714) 542-0737 www.powersystemstesting.com POWER Testing and Energization, Inc. 731 E. Ball Rd., Suite 100 Anaheim, CA 92805 (714) 507-2702 www.powerte.com
29
30
31
Tony Demaria Electric, Inc. 131 West F St. Wilmington, CA 90744 (310) 816-3130 x111 Fax: (310) 549-9747
[email protected] www.tdeinc.com Anthony Demaria
ColorAdo 25
Electric Power Systems, Inc. 6753 E. 47th Avenue Dr., Unit D Denver, CO 80216 (720) 857-7273 Fax: (303) 928-8020 www.eps-international.com
26
Electrical Reliability Services 7100 Broadway, Suite 7E Denver, CO 80221-2915 (303) 427-8809 Fax: (303) 427-4080 www.electricalreliability.com
Advanced Testing Systems 15 Trowbridge Dr. Bethel, CT 06801 (203) 743-2001 Fax: (203) 743-2325
[email protected] www.advtest.com Pat MacCarthy
floridA 34
C.E. Testing, Inc. 6148 Tim Crews Rd. Macclenny, FL 32063 (904) 653-1900 Fax: (904) 653-1911
[email protected] Mark Chapman
35
Electric Power Systems, Inc. 4436 Parkway Commerce Blvd. Orlando, FL 32808 (407) 578-6424 Fax: (407) 578-6408 www.eps-international.com
36
Electrical Reliability Services 11000 Metro Pkwy., Suite 30 Ft. Myers, FL 33966 (239) 693-7100 Fax: (239) 693-7772 www.electricalreliability.com
37
Industrial Electric Testing, Inc. 201 NW 1st Ave. Hallandale, FL 33009-4029 (954) 456-7020 www.industrialelectrictesting.com
American Electrical Testing Co., Inc. 34 Clover Dr. South Windsor, CT 06074 38 (860) 648-1013 Fax: (781) 821-0771
[email protected] www.99aetco.com Gerald Poulin EPS Technology 29 N. Plains Hwy., Suite 12 Wallingford, CT 06492 (203) 679-0145 www.eps-technology.com
32
High Voltage Maintenance Corp. 150 North Plains Industrial Rd. Wallingford, CT 06492 (203) 949-2650 Fax: (203) 949-2646 www.hvmcorp.com
33
Southern New England Electrical Testing, LLC 3 Buel St., Suite 4 Wallingford, CT 06492 (203) 269-8778 Fax: (203) 269-8775
[email protected] www.sneet.org David Asplund, Sr.
39
Industrial Electric Testing, Inc. 11321 West Distribution Ave. Jacksonville, FL 32256 (904) 260-8378 Fax: (904) 260-0737
[email protected] www.industrialelectrictesting.com Gary Benzenberg Industrial Electronics Group 850369 Highway 17 South PO Box 1870 Yulee, FL 32041 (904) 225-9529 Fax: (904) 225-0834
[email protected] www.industrialgroups.com Butch E. Teal
GeorGiA 40
Electrical Equipment Upgrading, Inc. 21 Telfair Pl. Savannah, GA 31415 (912) 232-7402 Fax: (912) 233-4355
[email protected] www.eeu-inc.com Kevin Miller
41
Electrical Reliability Services 2275 Northwest Pkwy. SE, Suite 180 Marietta, GA 30067 (770) 541-6600 Fax: (770) 541-6501 www.electricalreliability.com
For additional information on NETA visit netaworld.org
54
42
Electrical Testing, Inc. 2671 Cedartown Hwy. Rome, GA 3016-6791 (706) 234-7623 Fax: (706) 236-9028
[email protected] www.electricaltestinginc.com
49
Electrical Maintenance & Testing Inc. 12342 Hancock St. Carmel, IN 46032 (317) 853-6795 Fax: (317) 853-6799
[email protected] www.emtesting.com Brian K. Borst
43
Nationwide Electrical Testing, Inc. 6050 Southard Trace Cumming, GA 30040 (770) 667-1875 Fax: (770) 667-6578
[email protected] www.n-e-t-inc.com Shashikant B. Bagle
50
High Voltage Maintenance Corp. 8320 Brookville Rd., #E Indianapolis, IN 46239 (317) 322-2055 Fax: (317) 322-2056 www.hvmcorp.com
illinois
51
44
Dude Electrical Testing, LLC 145 Tower Dr., Suite 9 Burr Ridge, IL 60527 (815) 293-3388 Fax: (815) 293-3386
[email protected] www.dudetesting.com Scott Dude
45
Electric Power Systems, Inc. 23823 Andrew Rd. Plainfield, IL 60585 (815) 577-9515 Fax: (815) 577-9516 www.eps-international.com
46
High Voltage Maintenance Corp. 941 Busse Rd. Elk Grove Village, IL 60007 (847) 640-0005 www.hvmcorp.com
47
PRIT Service, Inc. 112 Industrial Dr. PO Box 606 Minooka, IL 60447 (815) 467-5577 Fax: (815) 467-5883
[email protected] www.pritserviceinc.com Rod Hageman
52
58
Tidal Power Services, LLC 1056 Mosswood Dr. Sulphur, LA 70663 (337) 558-5457 Fax: (337) 558-5305
[email protected] www.tidalpowerservices.com Steve Drake
Shermco Industries 2100 Dixon St., Suite C Des Moines, IA 50316 (515) 263-8482
[email protected] www.shermco.com Lynn Hamrick Shermco Industries 796 11th St. Marion, IA 52302 (319) 377-3377 Fax: (319) 377-3399
[email protected] www.shermco.com Lynn Hamrick
mAine 59
Electric Power Systems, Inc. 56 Bibber Pkwy., #1 Brunswick, ME 04011 (207) 837-6527 www.eps-international.com
60
Three-C Electrical Co., Inc. 72 Sanford Drive Gorham, ME 04038 (800) 649-6314 Fax: (207) 782-0162
[email protected] www.three-c.com Jim Cialdea
louisiAnA 53
Electric Power Systems, Inc. 1129 East Hwy. 30 Gonzalez, LA 70737 (225) 644-0150 Fax: (225) 644-6249 www.eps-international.com
54
Electrical Reliability Services 14141 Airline Hwy., Building 1, Suite X Baton Rouge, LA 70817 (225) 755-0530 Fax: (225) 751-5055 www.electricalreliability.com
indiAnA American Electrical Testing Co., Inc. 4032 Park 65 Dr. Indianapolis, IN 46254 (317) 487-2111 Fax: (781) 821-0771
[email protected] www.99aetco.com Stephen Canale
Tidal Power Services, LLC 8184 Hwy. 44, Suite 105 Gonzales, LA 70737 (225) 644-8170 Fax: (225) 644-8215
[email protected] www.tidalpowerservices.com Darryn Kimbrough
iowA
55
48
57
56
Electrical Reliability Services 9636 St. Vincent, Unit A Shreveport, LA 71106 (318) 869-4244 www.electricalreliabilty.com Electrical Reliability Services 121 E. Hwy108 Sulphur, LA 70665 (337) 583-2411 Fax: (337) 583-2410 www.electricalreliability.com
mArylAnd 61
ABM Electrical Power Solutions 3700 Commerce Dr., #901- 903 Baltimore, MD 21227 (410) 247-3300 Fax: (410) 247-0900 www.abm.com Bill Hartman
62
ABM Electrical Power Solutions 4390 Parliament Pl., Suite Q Lanham, MD 20706 (301) 967-3500 Fax: (301) 735-8953 www.abm.com Frank Ceci
63
Harford Electrical Testing Co., Inc. 1108 Clayton Rd. Joppa, MD 21085 (410) 679-4477 Fax: (410) 679-0800
[email protected] www.harfordtesting.com Vincent Biondino
For additional information on NETA visit netaworld.org
55 64
65
66
71
Potomac Testing, Inc. 1610 Professional Blvd., Suite A Crofton, MD 21114 (301) 352-1930 Fax: (301) 352-1936
[email protected] www.potomactesting.com Ken Bassett
DYMAX Service Inc. 46918 Liberty Dr. Wixom, MI 48393 (248) 313-6868 Fax: (248) 313-6869 www.dymaxservice.com Bruce Robinson
72
Electric Power Systems, Inc. 11861 Longsdorf St. Riverview, MI 48193 (734) 282-3311 www.eps-international.com
Reuter & Hanney, Inc. 11620 Crossroads Cir., Suites D - E Middle River, MD 21220 (410) 344-0300 Fax: (410) 335-4389 www.reuterhanney.com Michael Jester
mAssAChusetts 67
68
69
70
miChiGAn
High Voltage Maintenance Corp. 9305 Gerwig Ln., Suite B Columbia, MD 21046 (410) 309-5970 Fax: (410) 309-0220 www.hvmcorp.com
73
74
High Voltage Maintenance Corp. 24371 Catherine Industrial Dr., Suite 207 Novi, MI 48375 (248) 305-5596 Fax: (248) 305-5579 www.hvmcorp.com Northern Electrical Testing, Inc. 1991 Woodslee Dr. Troy, MI 48083-2236 (248) 689-8980 Fax: (248) 689-3418
[email protected] www.northerntesting.com Lyle Detterman
American Electrical Testing Co., Inc. 480 Neponset St., Bldg. 6 Canton, MA 02021-1970 (781) 821- 0121 Fax: (781) 821-0771
[email protected] www.99aetco.com 75 POWER PLUS Engineering, Inc. Scott A. Blizard 46575 Magallan Dr. Novi, MI 48377 High Voltage Maintenance Corp. (248) 344-0200 Fax: (248) 305-9105 24 Walpole Park South Dr.
[email protected] Walpole, MA 02081 www.epowerplus.com (508) 668-9205 Salvatore Mancuso www.hvmcorp.com Infra-Red Building and Power Service 152 Centre St. Holbrook, MA 02343-1011 (781) 767-0888 Fax: (781) 767-3462
[email protected] www.infraredbps.com Thomas McDonald Sr. Three-C Electrical Co., Inc. 40 Washington Street Westborough, MA 01581 (508) 881-3911 Fax: (508) 881-4814
[email protected] www.three-c.com Jim Cialdea
76
77
Powertech Services, Inc. 4095 South Dye Rd. Swartz Creek, MI 48473-1570 (810) 720-2280 Fax: (810) 720-2283
[email protected] www.powertechservices.com Kirk Dyszlewski
minnesotA 78
DYMAX Holdings, Inc. 4751 Mustang Cir. St. Paul, MN 55112 (763) 717-3150 Fax: (763) 784-5397
[email protected] www.dymaxservice.com Gene Philipp
79
High Voltage Service, Inc. 4751 Mustang Cir. St. Paul, MN 55112 (763) 717-3103 Fax: (763) 784-5397 www.hvserviceinc.com Mike Mavetz
missouri 80
81
82
Electric Power Systems, Inc. 6141 Connecticut Ave. Kansas City, MO 64120 (816) 241-9990 Fax: (816) 241-9992 www.eps-international.com Electric Power Systems, Inc. 21 Millpark Ct. Maryland Heights, MO 63043-3536 (314) 890-9999 Fax:(314) 890-9998 www.eps-international.com Electrical Reliability Services 348 N.W. Capital Dr. Lees Summit, MO 64086 (816) 525-7156 Fax: (816) 524-3274 www.electricalreliability.com
nevAdA 83
Utilities Instrumentation Service, Inc. 2290 Bishop Circle East 84 Dexter, MI 48130 (734) 424-1200 Fax: (734) 424-0031
[email protected] www.uiscorp.com Gary E. Walls 85
ABM Electrical Power Solutions 6280 South Valley View Blvd., Suite 618 Las Vegas, NV 89118 (702) 216-0982 Fax: (702) 216-0983 www.abm.com Jeff Militello Control Power Concepts 353 Pilot Rd, Suite B Las Vegas, NV 89119
[email protected] www.controlpowerconcepts.com Zeb Fettig Electrical Reliability Services 6351 Hinson St., Suite B Las Vegas, NV 89118 (702) 597-0020 Fax: (702) 597-0095 www.electricalreliability.com
For additional information on NETA visit netaworld.org
56
86
Electrical Reliability Services 1380 Greg St., Suite 217 Sparks, NV 89431 (775) 746-8484 Fax: (775) 356-5488 www.electricalreliability.com
87
Hampton Tedder Technical Services 4920 Alto Ave. Las Vegas, NV 89115 (702) 452-9200 Fax: (702) 453-5412 www.hamptontedder.com Roger Cates
93
Longo Electrical-Mechanical, Inc. One Harry Shupe Blvd., Box 511 Wharton, NJ 07855 (973) 537-0400 Fax: (973) 537-0404
[email protected] www.elongo.com Joe Longo
94
101 M&L Power Systems, Inc. 109 White Oak Ln., Suite 82 Old Bridge, NJ 08857 (732) 679-1800 Fax: (732) 679-9326
[email protected] www.mlpower.com Milind Bagle
American Electrical Testing Co., Inc. 76 Cain Dr. Brentwood, NY 11717 (631) 617-5330 Fax: (631) 630-2292
[email protected] www.99aetco.com Michael Schacker
95
102 Scott Testing Inc. 1698 5th St. Ewing, NJ 08638 (609) 882-2400 Fax: (609) 882-5660
[email protected] www.scotttesting.com Russ Sorbello
Elemco Services, Inc. 228 Merrick Rd. Lynbrook, NY 11563 (631) 589-6343 Fax: (631) 589-6670
[email protected] www.elemco.com Courtney O’Brien
103 Trace Electrical Services & Testing, LLC 293 Whitehead Rd. Hamilton, NJ 08619 (609) 588-8666 Fax: (609) 588-8667
[email protected] 104 www.tracetesting.com Joseph Vasta
High Voltage Maintenance Corp. 1250 Broadway, Suite 2300 New York, NY 10001 (718) 239-0359 www.hvmcorp.com
new hAmpshire 88
Electric Power Systems, Inc. 915 Holt Ave., Unit 9 Manchester, NH 03109 (603) 657-7371 Fax: (603) 657-7370 www.eps-international.com
new Jersey 89
90
91
92
American Electrical Testing Co., Inc. 96 50 Intervale Rd., Suite 1 Boonton, NJ 07005 (973) 316-1180 Fax: (781) 316-1181
[email protected] www.99aetco.com Jeff Somol Eastern High Voltage 11A South Gold Dr. Robbinsville, NJ 08691-1606 (609) 890-8300 Fax: (609) 588-8090
[email protected] www.easternhighvoltage.com Joseph Wilson High Energy Electrical Testing, Inc. 515 S. Ocean Ave. Seaside Park, NJ 08752 (732) 938-2275 Fax: (732) 938-2277
[email protected] www.highenergyelectric.com Charles Blanchard Longo Electrical-Mechanical, Inc. 1625 Pennsylvania Ave. Linden, NJ 07036 (908) 925-2900 Fax: (908) 925-9427
[email protected] www.elongo.com Joe Longo
100
new mexiCo 97
98
Electric Power Systems, Inc. 8515 Cella Alameda NE, Suite A Albuquerque, NM 87113 (505) 792-7761 www.eps-international.com
99
A&F Electrical Testing, Inc. 80 Lake Ave. S., Suite 10 Nesconset, NY 11767 (631) 584-5625 Fax: (631) 584-5720
[email protected] www.afelectricaltesting.com Kevin Chilton
HMT, Inc. 6268 Route 31 Cicero, NY 13039 (315) 699-5563 Fax: (315) 699-5911
[email protected] www.hmt-electric.com John Pertgen
north CArolinA 105
Electrical Reliability Services 8500 Washington Pl. NE, Suite A-6 Albuquerque, NM 87113 (505) 822-0237 Fax: (505) 822-0217 www.electricalreliability.com
new york
A&F Electrical Testing, Inc. 80 Broad St., 5th Floor New York, NY 10004 (631) 584-5625 Fax: (631) 584-5720
[email protected] www.afelectricaltesting.com Florence Chilton
106
ABM Electrical Power Solutions 3600 Woodpark Blvd., Suite G Charlotte, NC 28206 (704) 273-6257 Fax: (704) 598-9812
[email protected] www.abm.com Ernest Goins ABM Electrical Power Solutions 5805 G Departure Dr. Raleigh, NC 27616 (919) 877-1008 Fax: (919) 501-7492 www.abm.com Rob Parton
For additional information on NETA visit netaworld.org
57
107
108
109
110
111
112
113
114
115 ELECT, P.C. 7400-G Siemens Rd. PO Box 2080 Wendell, NC 27591 (919) 365-9775 Fax: (919) 365-9789
[email protected] www.elect-pc.com 116 Barry W. Tyndall
Electric Power Systems, Inc. 319 US Hwy. 70 E, Unit E Garner, NC 27529 (919) 322-2670 www.eps-international.com
117
Electrical Reliability Services 6135 Lakeview Road, Suite 500 Charlotte, NC 28269 (704) 441-1497 www.electricalreliability.com Power Products & Solutions, Inc. 12465 Grey Commercial Rd. Midland, NC 28107 (704) 573-0420 x12 Fax: (704) 573-3693
[email protected] www.powerproducts.biz Ralph Patterson
Electrical Reliability Services 610 Executive Campus Dr. Westerville, OH 43082 (877) 468-6384 Fax: (614) 410-8420
[email protected] www.electricalreliability.com High Voltage Maintenance Corp. 5100 Energy Dr. Dayton, OH 45414 (937) 278-0811 Fax: (937) 278-7791 www.hvmcorp.com High Voltage Maintenance Corp. 7200 Industrial Park Blvd. Mentor, OH 44060 (440) 951-2706 Fax: (440) 951-6798 www.hvmcorp.com
118
Power Services, LLC 998 Dimco Way, PO Box 750066 Centerville, OH 45475 (937) 439-9660 Fax: (937) 439-9611
[email protected] Mark Beucler
119
Power Solutions Group, Ltd. 670 Lakeview Plaza Blvd. Columbus, OH 43085 (614) 310-8018
[email protected] www.powersolutionsgroup.com Stuart Spohn
Power Test, Inc. 2200 Hwy. 49 Harrisburg, NC 28075 (704) 200-8311 Fax: (704) 455-7909 120 Power Solutions Group, Ltd.
[email protected] 425 W. Kerr Rd. www.powertestinc.com Tipp City, OH 45371 Richard Walker (937) 506-8444 Fax: (937) 506-8434
[email protected] ohio www.powersolutionsgroup.com Barry Willoughby CE Power Solutions, LLC 4500 W. Mitchell Ave. oklAhomA Cincinnati, OH 45232 (513) 563-6150 Fax: (513) 563-6120 121 Shermco Industries
[email protected] 1357 N. 108th E. Ave. Rhonda Harris Tulsa, OK 74116 (918) 234-2300 DYMAX Service, Inc.
[email protected] 4213 Kropf Ave. www.shermco.com Canton, OH 44706 Jim Harrison (330) 484-6801 Fax: (740) 333-1271 www.dymaxservice.com oreGon Gary Swank 122 Electrical Reliability Services Electric Power Systems, Inc. 4099 SE International Way, Suite 201 2601 Center Rd., #101 Milwaukie, OR 97222-8853 Hinckley, OH 44233 (503) 653-6781 Fax: (503) 659-9733 (330) 460-3706 Fax: (330) 460-3708 www.electricalreliability.com www.eps-international.com
123
Taurus Power & Controls, Inc. 9999 SW Avery St. Tualatin, OR 97062-9517 (503) 692-9004 Fax: (503) 692-9273
[email protected] www.tauruspower.com Rob Bulfinch
pennsylvAniA 124
ABM Electrical Power Solutions 710 Thomson Park Dr. Cranberry Township, PA 16066-6427 (724) 772-4638 Fax: (724) 772-6003
[email protected] www.abm.com William (Pete) McKenzie
125
American Electrical Testing Co., Inc. Green Hills Commerce Center 5925 Tilghman St., Suite 200 Allentown, PA 18104 (215) 219-6800
[email protected] www.99aetco.com Jonathan Munley
126
Burlington Electrical Testing Co., Inc. 300 Cedar Ave. Croydon, PA 19021-6051 (215) 826-9400 x221 Fax: (215) 826-0964
[email protected] www.betest.com Walter P. Cleary
127
Electric Power Systems, Inc. 1090 Montour West Industrial Blvd. Coraopolis, PA 15108 (412) 276-4559 www.eps-international.com
128
Electric Power Systems, Inc. 2495 Boulevard of the Generals Norristown, PA 19403 (610) 630-0286 www.eps-international.com
129
130
EnerG Test 204 Gale Lane, Bldg. 2 – 2nd Floor Kennett Square, PA 19348 (484) 731-0200 Fax: (484) 713-0209
[email protected] www.energtest.com Katie Bleiler High Voltage Maintenance Corp. 355 Vista Park Dr. Pittsburgh, PA 15205-1206 (412) 747-0550 Fax: (412) 747-0554 www.hvmcorp.com
For additional information on NETA visit netaworld.org
58
131
132
133
Longo Electrical-Mechanical, Inc. 1400 F Adams Road Bensalem, PA 19020 (215) 638-1333 Fax: (215) 638-1366
[email protected] www.elongo.com Joe Longo North Central Electric, Inc. 69 Midway Ave. Hulmeville, PA 19047-5827 (215) 945-7632 Fax: (215) 945-6362
[email protected] Robert Messina Reuter & Hanney, Inc. 149 Railroad Dr. Northampton Industrial Park Ivyland, PA 18974 (215) 364-5333 Fax: (215) 364-5365
[email protected] www.reuterhanney.com Michael Reuter
135
139
140
141
south CArolinA 134
138
Power Products & Solutions, Inc. 13 Jenkins Ct. Mauldin, SC 29662 (800) 328-7382
[email protected] www.powerproducts.biz Raymond Pesaturo
142
Power Solutions Group, Ltd. 135 Old School House Rd. 143 Piedmont, SC 29673 (864) 845-1084 Fax: (864) 845-1085
[email protected] www.powersolutionsgroup.com Frank Crawford
tennesee 136
137
144 Electric Power Systems, Inc. 146 Space Park Dr. Nashville, TN 37211 (615) 834-0999 Fax: (615) 834-0129 www.eps-international.com
Electrical & Electronic Controls 6149 Hunter Rd. Ooltewah, TN 37363 (423) 344-7666 x23 Fax: (423) 344-4494
[email protected] Michael Hughes
145
Power & Generation Testing, Inc. 146 480 Cave Rd. Nashville, TN 37210 (615) 882-9455 Fax: (615) 882-9591
[email protected] www.pgti.net Mose Ramieh
Saber Power Systems 9841 Saber Power Lane Rosharon, TX 77583 (713) 222-9102
[email protected] www.saberpower.com Ron Taylor
texAs
Shermco Industries 33002 FM 2004 Angleton, TX 77515 (979) 848-1406 Fax: (979) 848-0012
[email protected] www.shermco.com Malcom Frederick
147
Absolute Testing Services, Inc. 6829 Guhn Rd. Houston, TX 77040 (832) 467-4446 Fax: (713) 849-3885
[email protected] www.texasats.com Richard Gamble 148 Shermco Industries 1705 Hur Industrial Blvd. Electric Power Systems, Inc. Cedar Park, TX 78613 4100 Greenbriar Dr., Suite 160 (512) 267-4800 Fax: (512) 258-5571 Stafford, TX 77477
[email protected] (713) 644-5400 www.shermco.com www.eps-international.com Kevin Ewing Electrical Reliability Services 149 1057 Doniphan Park Cir., Suite A El Paso, TX 79922 (915) 587-9440 Fax: (915) 587-9010 www.electricalreliability.com Electrical Reliability Services 1426 Sens Rd., Suite 5 Houston, TX 77571 (281) 241-2800 Fax: (281) 241-2801 www.electricalreliability.com Grubb Engineering, Inc. 3128 Sidney Brooks San Antonio, TX 78235 (210) 658-7250 Fax: (210) 658-9805
[email protected] www.grubbengineering.com Robert D. Grubb Jr. National Field Services 649 Franklin St. Lewisville,TX 75057 (972) 420-0157 www.natlfield.com Eric Beckman Power Engineering Services, Inc. 9179 Shadow Creek Ln. Converse,TX 78109 (210) 590-4936 Fax: (210) 590-6214
[email protected] www.pe-svcs.com Miles R. Engelke
150
151
Shermco Industries 2425 E. Pioneer Dr. Irving, TX 75061 (972) 793-5523 Fax: (972) 793-5542
[email protected] www.shermco.com Ron Widup Shermco Industries 12000 Network Blvd., Bldg. D, Suite 410 San Antonio, TX 78249 (512) 267-4800 Fax: (512) 267-4808
[email protected] www.shermco.com Kevin Ewing Tidal Power Services, LLC 4202 Chance Ln. Rosharon, TX 77583 (281) 710-9150 Fax: (713) 583-1216
[email protected] www.tidalpowerservices.com Monty C. Janak
utAh 152
153
Electrical Reliability Services 3412 South 1400 West, Unit A West Valley City, UT 84119 (801) 975-6461 www.electricalreliability.com Western Electrical Services, Inc. 3676 W. California Ave.,#C-106 Salt Lake City, UT 84104
[email protected] www.westernelectricalservices.com Rob Coomes
For additional information on NETA visit netaworld.org
59
virGiniA
162
Taurus Power & Controls, Inc. 6617 S. 193rd Pl., Suite P104 Kent, WA 98032 (425) 656-4170 Fax: (425) 656-4172
[email protected] www.tauruspower.com Jim Lightner
163
Western Electrical Services, Inc. 14311 29th St. East Sumner, WA 98390 (253) 891-1995 Fax: (253) 891-1511
[email protected] www.westernelectricalservices.com Dan Hook
154
ABM Electrical Power Solutions 814 Greenbrier Cir., Suite E Chesapeake, VA 23320 (757) 548-5690 Fax: (757) 548-5417 www.abm.com Mark Anthony Gaughan, III
155
Electric Power Systems, Inc. 827 Union St. Salem, VA 24153 (540) 375-0084 Fax: (540) 375-0094 www.eps-international.com
156
Potomac Testing, Inc. 11179 Hopson Rd., Suite 5 164 Western Electrical Services, Inc. Ashland, VA 23005 4510 NE 68th Dr., Suite 122 (804) 798-7334 Fax: (804) 798-7456 Vancouver, WA 98661 www.potomactesting.com (888) 395-2021 Fax: (253) 891-1511
[email protected] Reuter & Hanney, Inc. www.westernelectricalservices.com 4270-I Henninger Ct. Tony Asciutto Chantilly, VA 20151 (703) 263-7163 Fax: (703) 263-1478 www.reuterhanney.com wisConsin
157
wAshinGton 158
Electrical Reliability Services 2222 West Valley Hwy. N., Suite 160 Auburn, WA 98001 (253) 736-6010 Fax: (253) 736-6015 www.electricalreliability.com
159
POWER Testing and Energization, Inc. 22035 70th Ave. South Kent, WA 98032 (253) 872-7747 www.powerte.com
160
POWER Testing and Energization, Inc. 14006 NW 3rd Ct., Suite 101 Vancouver, WA 98685 (360) 597-2800 Fax: (360) 576-7182
[email protected] www.powerte.com Chris Zavadlov
161
165
CE Power Solutions of Wisconsin, LLC 3100 East Enterprise Ave. Appleton, WI 54913 (920) 968-0281 Fax: (920) 968-0282
[email protected] Rob Fulton
166
Electrical Energy Experts, Inc. W129N10818, Washington Dr. Germantown,WI 53022 (262) 255-5222 Fax: (262) 242-2360
[email protected] www.electricalenergyexperts.com William Styer
167
Electrical Testing Solutions 2909 Green Hill Ct. Oshkosh, WI 54904 (920) 420-2986 Fax: (920) 235-7136
[email protected] www.electricaltestingsolutions.com Tito Machado
168
169
Energis High Voltage Resources, Inc. 1361 Glory Rd. Green Bay, WI 54304 (920) 632-7929 Fax: (920) 632-7928
[email protected] www.energisinc.com Mick Petzold High Voltage Maintenance Corp. 3000 S. Calhoun Rd. New Berlin, WI 53151 (262) 784-3660 Fax: (262) 784-5124 www.hvmcorp.com
Sigma Six Solutions, Inc. 2200 West Valley Hwy., Suite 100 Auburn, WA 98001 (253) 333-9730 Fax: (253) 859-5382
[email protected] www.sigmasix.com John White
For additional information on NETA visit netaworld.org
60
canada 170
178
Magna IV Engineering 200, 688 Heritage Dr. SE Calgary, AB T2H1M6 Canada (403) 723-0575 Fax: (403) 723-0580
[email protected] Virginia Balitski 179
171
172
173
174
175
176
177
Magna IV Engineering 1005 Spinney Dr. Dawson Creek, BC V1G 1K1 Canada (780) 462-3111 Fax: (780) 462-9799
[email protected] Magna IV Engineering 1103 Parsons Rd. SW Edmonton, AB T6X 0X2 Canada (780) 462-3111 Fax: (780) 450-2994
[email protected] www.magnaiv.com Virginia Balitski Magna IV Engineering 106, 4268 Lozells Ave Burnaby, BC VSA 0C6 Canada (604) 421-8020 Magna IV Engineering 8219D Fraser Ave. Fort McMurray, AB T9H 0A2 Canada (780) 791-3122 Fax: (780) 791-3159
[email protected] Virginia Balitski Magna IV Engineering 1040 Winnipeg St. Regina, SK S4R 8P8 Canada (306) 585-2100 Fax: (306) 585-2191
[email protected] Peter Frostad Magna Electric Corporation 3430 25th St. NE Calgary, AB T1Y 6C1 Canada (403) 769-9300 Fax: (403) 769-9369
[email protected] www.magnaelectric.com Cal Grant
180
Magna Electric Corporation 1033 Kearns Crescent, Box 995 Regina, SK S4P 3B2 Canada (306) 949-8131 Fax: (306) 522-9181
[email protected] www.magnaelectric.com Kerry Heid Magna Electric Corporation 851-58th St. East Saskatoon, SK S7K 6X5 Canada (306) 955-8131 x5 Fax: (306) 955-9181
[email protected] www.magnaelectric.com Luis Wilson Magna Electric Corporation 1375 Church Ave. Winnipeg, MB R2X 2T7 Canada (204) 925-4022 Fax: (204) 925-4021
[email protected] www.magnaelectric.com Curtis Brandt
BrUSSelS 184
Shermco Industries Boulevard Saint-Michel 47 1040 Brussels, Brussels, Belgium +32 (0)2 400 00 54 Fax: +32 (0)2 400 00 32
[email protected] www.shermco.com Paul Idziak
chile
185
Magna IV Engineering Avenida del Condor Sur #590 Officina 601 Huechuraba, Santiago 8580676 Chile +(56) 9-9-517-4642
[email protected] Cristian Fuentes
PUerto rico 186
181
Orbis Engineering Field Services Ltd. #300, 9404 - 41st Ave. Edmonton, AB T6E 6G8 Canada (780) 988-1455 Fax: (780) 988-0191
[email protected] www.orbisengineering.net Lorne Gara
182
Pacific Powertech Inc. #110, 2071 Kingsway Ave. Port Coquitlam, BC V3C 1T2 Canada (604) 944-6697 Fax: (604) 944-1271
[email protected] www.pacificpowertech.ca Josh Conkin
183
REV Engineering, LTD 3236 - 50 Ave. SE Calgary, AB T2B 3A3 Canada (403) 287-0156 Fax: (403) 287-0198
[email protected] www.reveng.ca Roland Nicholas Davidson, IV
Phasor Engineering Sabaneta Industrial Park #216 Mercedita, Puerto Rico 00715 (787) 844-9366 Fax: (787) 841-6385
[email protected] Rafael Castro
Magna Electric Corporation 3731-98 Street Edmonton, AB T6E 5N2 Canada (780) 436-8831 Fax: (780) 463-9646
[email protected] www.magnaelectric.com Franz Granacher
REV 01.14
For additional information on NETA visit netaworld.org
ABOUT THE INTERNATIONAL ELECTRICAL TESTING ASSOCIATION The InterNational Electrical Testing Association (NETA) is an accredited standards developer for the American National Standards Institute (ANSI) and defines the standards by which electrical equipment is deemed safe and reliable. NETA Certified Technicians conduct the tests that ensure this equipment meets the Association’s stringent specifica-tions. NETA is the leading source of specifications, procedures, testing, and requirements, not only for commissioning new equipment but for testing the reliability and performance of existing equipment.
CERTIFICATION Certification of competency is particularly important in the electrical testing industry. Inherent in the determination of the equipment’s serviceability is the prerequisite that individuals performing the tests be capable of conducting the tests in a safe manner and with complete knowledge of the hazards involved. They must also evaluate the test data and make an informed judgment on the continued serviceability, deterioration, or nonserviceability of the specific equipment. NETA, a nationally-recognized certification agency, provides recognition of four levels of competency within the electrical testing industry in accordance with ANSI/NETA ETT-2000 Standard for Certification of Electri-cal Testing Technicians.
QUALIFICATIONS OF THE TESTING ORGANIZATION An independent overview is the only method of determining the long-term usage of electrical apparatus and its suitability for the intended purpose. NETA Accredited Companies best support the interest of the owner, as the objectivity and competency of the testing firm is as important as the competency of the individual technician. NETA Accredited Companies are part of an independent, third-party electrical testing associa-tion dedicated to setting world standards in electrical maintenance and acceptance testing. Hiring a NETA Accredited Company assures the customer that: • The NETA Technician has broad-based knowledge — this person is trained to inspect, test, maintain, and calibrate all types of electrical equipment in all types of industries. • NETA Technicians meet stringent educational and experience requirements in accordance with ANSI/NETA ETT-2000 Standard for Certification of Electrical Testing Technicians. • A Registered Professional Engineer will review all engineering reports • All tests will be performed objectively, according to NETA specifications, using cali-brated instruments traceable to the National Institute of Science and Technology (NIST). • The firm is a well-established, full-service electrical testing business.
Setting the Standard
