Wave shape standard wave shape of impulse voltage is 1. Page 3 of 9 standard work practice sp0507 ver 5 ergon energy corporation limited abn 50 087 646 062 ergon energy queensland pty ltd abn 11 121 177 802 rated knee point voltage 950 volts, maximum secondary winding resistance 3 ohms. Worst case fault conditions are imposed at the output of the transformer shortcircuit conditions and separate overload conditions. These are the most commonly used transformer types for all the applications. Testing potential transformers relay testing training for. By this way,the next impulse voltage waveform is applied. This test is conducted to determine the iron losses or core losses and parameters r0 and x0 of the transformer. Magnetization and primary injection test of current. The losses that are generated inside the transformer on load appear as heat. The tests this laboratory is able to carry out are the following. Page 2 of 14 standard work practice sp0504 ver 4 ergon energy corporation limited abn 50 087 646 062. The various types of transformer shown in the figure above are explained in detail below.
Types of transformer field tests and diagnostics bright. Pdf transformer is a static device which transforms a. Different test like thermography, insulation resistance test, transformer turns ratio test. Both paper and oil which are used for insulation in the transformer start get.
Hence every electrical power transformer must undergo through vector group test of transformer at factory site for ensuring the customer specified vector group of transformer. Oct 11, 2015 testing facilities impulse generator discharge circuit recording system voltage divider for measurement standard impulse wave impulse withstand test 15. The performance parameters of interest can be obtained by solving that circuit for any load conditions. Prior to testing, short the primary winding of the ct under test by connecting h1 and h2, then short the secondary winding of the ct under test by connecting x1 and x2x5. Power factor testing insulation power factor tests are used to measure dielectric losses, which relate the wetness, dryness or deterioration of transformer insulation. Inspect transformer and parts for shipping damage and moisture. C electrical power from one voltage to another voltage keeping the frequency same by. Current transformer testing swp check this is the latest process zone version before use. Our dtts aims at a highly automated test procedure using wellprepared sequences and minimal manual intervention to keep the test duration of a single transformer as short as possible and to avoid human errors.
Page 1 of 14 standard work practice sp0504 ver 4 ergon energy corporation limited abn 50 087 646 062 ergon energy queensland pty ltd abn 11 121 177 802 1. Transformer design to withstand switching must add strength 1. This type of transformer is categorized on the basis of a number of turns in the primary and secondary windings and the induced emf. Different types of transformers and their applications. Mainly two types of transformer testing are done at manufacturer premises type test of transformer and routine test of transformer. Some transformer tests are carried out for confirming the basic design expectation of that transformer. Transformer oil and other insulating liquids suffer from electrical and mechanical stresses while a transformer is in operation. Here we discuss different types of transformers are the step up and step down transformer, distribution transformer, potential transformer, power transformer, 1. In addition there are contaminations caused due to chemical interactions with windings and other solid insulations, catalyzed by high operating temperature. Feb 08, 2015 a routine test of transformer is mainly for confirming operational performance of individual unit in a production lot.
Transformer operates when both circuits take effect of mutual induction. The secondary voltage bears a fixed relation with the. In this article, you will learn different types of transformer testing methods, test setup, and their acceptance criteria. The insulation of the transformer is the one to get a. Transformer only stepup or stepdown the level of ac voltage or ac current. An electrical power transformer has to go through a number of transformer testing procedures for confirming its specifications and performances. Testing and commissioning instrumenttransformers free download as powerpoint presentation. The tap position of the transformer during test is determined according to test conditions. It is a good idea to remove all as a safety precaution to prevent backfeeding dangerous voltages into the system during testing. Testing power factor is a means of measuring the integrity of the insulation, since the smaller the power factor, the better the insulator. Remove the neutral ground and isolate the ct from any associated burden. To maximize the life span and effectiveness of a transformer, it is significant to carry out transformer testing to find out possible faults and rectify it in advance. Ltc because in order to change taps, the transformer has to be taken out of service or at least disconnected from the load.
Transformer testing has developed considerably over the past years. The international electrical testing association neta is an accredited standards developer for the american national standards institute ansi. Transformer cant stepup or stepdown the level of dc voltage or dc current. Impulse test concepts by philip j hopkinson, pe conclusions.
Insulation tests on current transformers rated 600v or less are usually performed at vdc. Instrument transformer theory and testing steve hudson, pe engineering manager 10737 lexington drive knoxville, tn 37932 phone. Power factor testing a twowinding transformer is conducted by energizing the winding at a known ac voltage typically 10 kv for windings rated greater than 10 kv with the common winding bushings shorted together. Testing facilities impulse generator discharge circuit recording system voltage divider for measurement standard impulse wave impulse withstand test 15. Routine tests are carried out on every unit manufactured. It evolved from the simple gonogo verdict into a sophisticated segment within transformer manufacturing. Power factor testing a twowinding transformer is conducted by. In this test, the rated voltage is applied to the primary usually lowv. The equivalent circuit parameters areavailabletothedesigner ofthetransformers.
Testing potential transformers relay testing training. A routine series of diagnostics and testing for your current transformer should include ct saturation testing to identify the knee point against ieee or iec standards, ct ratio tests to identify that the voltage ratio is within expected parameters and current transformer resistance testing for both the transformer windings and ct insulation. Type test and routine test of transformer electrical mastar. Basics, maintenance, and diagnostics xi contents continued page 9.
Potential transformer testing ptvt valence electrical. Some transformer tests are also carried out at the consumer site before commissioning and also periodically in regular and emergency basis throughout its service life. Most failures of electrical power equipment are the result of a breakdown in the insulation system. Transformer rfq form to request a specific part to meet your requirements. All transformers are subjected to the following routine tests.
Verify correct operation of transformer withdrawal mechanism and grounding operation. This is one of the best testing techniques for predictive and preventive maintenance power factor testing also makes it possible to detect equipment insulation problems without making an internal visual inspection. Potential transformer testing ptvt i cowrote an article for the neta world magazine in 20042005 that covers several different manual techniques for potential transformer testing that explains several lowtech solutions for potential transformer testing. To understand the nature of ratio testing it is important to understand the applicable definitions. Different test like thermography, insulation resistance test, transformer turns ratio test, dissolved gas analysis. There are various test required on transformer to conform performance of transformer. Instrument transformer testing instrument transformers for metering purposes must have a high degree of accuracy up to class 0. When the pt is withdrawn ensure that there is no longer any connection with the primary electrical system. The potential transformer is made with highquality core operating at low flux density so that the magnetising current is small. Instrument transformers for metering purposes must have a high degree of accuracy up to class 0. Periodically monitoring and preventive maintenance can detect the defects before major damage has been occurred. The onoff impulse voltages are applied to each high voltage terminal sequentially.
Figure 5 shows the result of the curve fitting for core 1, considering the y axis to be the current and x axis to be the. Mainly two types of transformer testing are done at manufacturer premisestype test of transformer and routine test of transformer. Routine tests and type tests of transformers electrical4u. May 10, 20 transformer manufacturers perform two main types of transformer testing type test of transformer and routine test of transformer. To prove that the transformer meets customers specifications and design expectations, the transformer has to go through different testing procedures in manufacturer premises. Neta defines the standards by which electrical equipment is deemed safe and reliable.
That means routine tests of transformer include all the type tests except temperature rise and vacuum tests. The residual flux can be as much as 50 to 90% of the maximum operating flux, depending on the type of. In addition some other tests are also carried out by the consumer at site before commissioning and also. Testing of power transformers seems like a similar experience. Scribd is the worlds largest social reading and publishing site. This heats the transformer and the temperature of the transformer increases. Figure 1 and 2 shows connections diagrams for testing threephase transformer using alternate singlephase source. Performance test of faulty distribution transformers along. Transformer abnormal testing is required on safety isolation transformers to insure that the transformer output remains below hazardous voltage levels during fault conditions in the secondary circuit. Oil pressure test on transformer to check against leakages past joints and gaskets. Modeling and testing of ethernet transformers article pdf available in ieee transactions on magnetics 4510. Potential transformer pt definition the potential transformer may be defined as an instrument transformer used for the transformation of voltage from a higher value to the lower value.
This transformer step down the voltage to a safe limit value which can be easily measured by the ordinary low voltage instrument like a voltmeter, wattmeter and watthour meters, etc. Figure 5 shows the result of the curve fitting for core 1, considering the y axis to be the current and x axis to be the voltage, the following expression give the standard. Open as well as shorted terminals of nontested windings conclusions. Know about different types of transformers and its uses transformer one of the oldest innovations in electrical engineering. Fat or acceptance test or witness test or joint inspection test is. The vector group of transformer is an essential property for successful parallel operation of transformers.
Because a test confirms what you know, if you can apply in real life what you have learned in a classroom, under strict, rigorous and controlled conditions. In this book we have laid down important aspects on transformer. Sep 26, 2017 mainly two types of transformer testing are done at manufacturer premisestype test of transformer and routine test of transformer. Hence, it is essential to inspect and calibrate those instrument transformers at regular intervals. Download fulltext pdf power factor testing of drytype transformers article pdf available in regions magazine 1114 april 2012 with 536 reads. In some cases, cts may have to be tested by connecting test leads to both ends of an installed bushing. In addition to that some transformer tests are also carried out at the consumer site before commissioning and also periodically in regular and emergency basis through out its service life. A transformer is an electrical device that can be used to transfer the power from one circuit and another circuit without physical contact and without changing its characteristics like frequency, phase. In this article, performance test of faulty distribution transformersalong the streets or roads of port harcourt shall enumerate the methodology employed to identify the status condition of a faulty. They are designed for connection linetoline or linetoneutral in the same manner as ordinary voltmeters. Understanding transformer abnormal testing certifigroup. Types of transformer different types of transformer. Chincholi, nashik abstractmany high end electronic equipments, rapidly expanding computer control systems and information networks are sensitive to. Vector group test of power transformer electrical4u.
The voltage ratio of a transformer is the ratio of the rms terminal voltage of a. Silsbee contents t page introduction 317 generalprinciples 318 nullmethod 321 deflectionmethod 325 experimentalresults. Jun 17, 2016 testing power factor is a means of measuring the integrity of the insulation. The need for a comprehensive current transformer testing regime is evident when the alternative is considered. To keep failures at a minimum, periodic maintenance testing of the insulation is recommended to indicate whether it is deteriorating, and how fast. Transformer pd and induced voltage withstand test system.
In addition to that some transformer tests are also carried out at the consumer site before commissioning. On distribution transformer this type of switch may also be used to change nameplate voltage andor configuration. The oil pressure test on transformer to check against leakages past joints and gaskets is included. Magnetization and primary injection test of current transformer for protective relaying jacob tsado 8 current transformers. Before proceding with transformer measurements the test engineer will become familiar with the safety rules of section 2. These tests are done mainly in a prototype unit not in all manufactured units. Power transformer testing swp check this is the latest process zone version before use.
A fault leading to an open secondary could cause the primary current to overwhelm the. The terminal of the transformer should be designed so that the variation of the voltage ratio with load is minimum and the phase shift between the input and output voltage is also minimum. Potential transformers used primarily in a step down environment to monitor voltage. Following is an approximate sequence for transformer testing. Mainly two types of transformer are done by manufacturer before dispatching the transformer mainly 1 type test of transformer and 2 routine test. Both factory and field testing are performed to verify the insulation integrity of substation transformers. Cts should be tested before they are mounted on the transformer. If the cts are already mounted in the transformer, large highcapacity current testing leads can be. The results of overall power factor tests on power transformers reflect the insulation condition of the.
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