Transformer testing type tests and routine tests of. This test also performed as a routine test of transformer. Different test like thermography, insulation resistance test, transformer turns ratio test, dissolved gas analysis. To understand the basic working principle of a transformer. Sumpners test give more accurate results of regulation. If the two transformers are connected in parallel, then the polarity should be known for the proper connection of the transformer. This test is performed by applying rated voltage to the low voltage side and leaving the high voltage side open. You have to finish following quiz, to start this quiz. In this paper, various intelligence techniques are used to test transformer. Turnsratio test results should not deviate more than onehalf percent from either the adjacent coils or the calculated ratio. The methods used during tests and measurements of the power transformers, test and measurement circuits, calculations and evaluation criterias are included in this manual. Unless appropriate allowances are made, dependent on transformer designs and manufacturers, there is a risk that there will be false positives in the analysis. In an ideal insulator, as the insulating material which acts as dielectric too, is 100 % pure, the electric current passing through the insulator, only have capac. It has been developed with the assistance of bureau of reclamation engineers.
There are various test required on transformer to conform performance of transformer. This is sometimes listed on the transformers enclosure. If the transformer is new, the resistance test also serves as a verification of the manufacturers work. All transformers are subjected to the following routine tests. This is sometimes listed on the transformer s enclosure. Transformer nameplate ratio, tnr ratio between the specific labelled linetoline voltage of a higher voltage winding to a.
The type and routine test are very important for transformer. There are two types of polarity one is additive, and another is subtractive. Standard for acceptance testing specifications for electrical. We are pleased to submit the insulating fluid report and test sheets for the three 3 transformers and one 1 ocb located at the north vancouver facility. Many transformer faults or problems will cause a change in the dc resistance measured from the bushings shorted turns, open turns, poor joints or contacts. Insulation resistance test of transformer is one of the most important transformer tests we can perform this test at factory or site this test can be classified under type test, routine test, precommissioning and commissioning tests, periodic maintenance transformer tests you can know more about transformer testing and its. Power transformer testing power transformer factory test using ieee standards waldemar ziomek cg power systems canada ieee training, houston, texas, oct. First of all the current generated during the differential stability test is calculated using the % z voltage and source to feed the current will have to be chosen. 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. Mainly two types of transformer testing are done at manufacturer premises type. Feb 08, 2015 a routine test of transformer is mainly for confirming operational performance of individual unit in a production lot. Namely, if testing is based on injecting only one sequence current component at the time on both ct inputs of the. Field testing of a power transformer before putting into service 50mva.
Hence, the information derived from the resistance test is very useful in analyzing faults. Hipot test is typically used for acceptance testing or after transformer repair testing. Polarity test of transformer polarity means the direction of the induced voltages in the primary and the secondary winding of the transformer. Transformer testing type test and routine test of transformer electrical4u. The location of the station and the position of the equipment within the station. This test can be repeated during the service life of the transformer and verified against the result obtained during manufacturing, as a check to determine if the insulation is malfunctioning or decaying.
Before conducting a transformer winding resistance test, it is important to observe all safety warnings and take proper precautions. The equivalent model of a real transformer is as follows. Mainly two types of transformer testing are done at manufacturer premises type test of transformer and routine test of transformer. The following sections of the ansineta standard for acceptance testing specifications for. Transformers have been used at powerplants since the inception of. Basics, maintenance, and diagnostics vii contents continued page 4. Factory tests not achieving as much winding stress as field conditions 2.
You can test one with a multimeter using either the voltage testing function or the resistance testing function. Aug 05, 2016 video lecture on open circuit test and short circuit test on transformer of chapter single phase transformer of subject basic electrical engineering for firstyear engineering students. The preference is that all large power transformers 1 mva be tested with ttr test set. Electrical transformer quiz questions electrician exams. When ac hipot tests are used for routine maintenance, the power transformer can be examined at.
To test your transformer, simply touch the red and black pins of your ohmmeter to the opposite ends of the transformers wiring. As it checks the quality of material used and the procedure of transformer manufacturing hence provide us details of life of transformer, the transformer behaviour on different faults. Transformers regulate the voltage in circuits, but in some cases these can go bad and cause a circuit to not. Various influences can impact the expected lifetime throughout a transformers lifecycle. Testing of three phase power transformer ijireeice. It evolved from the simple gonogo verdict into a sophisticated segment within transformer manufacturing. The most common cause of transformer overheating and burnout is the result of misuse, connecting the charger to a battery system of lower voltage than specified for the charger. The procedure of the transformer ratio test is simple. The test is performed with a power factor test kit, and the connections are the same as for the megger test the insulation resistance test. The transformer sampling was performed by james powell on june 7, 2016 in accordance with astm d923 and d36 standards. Transformer testing has developed considerably over the past years. Cts should be tested before they are mounted on the transformer. Turnsratio test results should not deviate more than. Open circuit test and short circuit test on transformer.
Series resonances are occurring between leakage reactance of transformer and capacitance to ground. Condition of the test transformer regarding its temperature, oil level, tap position and mechanical appearance. A low voltage of around 510% is applied to that hv side with the help of a variac i. Factory tests are on transformer without load and without cables 3. As power transformer is highly expensive as well as important part of distribution system. The typical excitation current test data pattern for a threelegged core transformer is two similar current readings and one lower current reading. Open circuit voltage, transformer test procedure transformer failure can be the result of natural aging, premature shorting of adjacent coil wires, or overheating damage. To test your transformer, simply touch the red and black pins of your ohmmeter to the opposite ends of the transformer s wiring. When ac hipot tests are used for routine maintenance, the power transformer can be examined at rated voltage for 3 min instead of testing at 65% of factory test.
May 10, 20 so transformer ratio test is an essential type test of transformer. Insulation resistance tests megger test are carried out on all windings, core and core clamping bolts. The transformer sampling was performed by james powell on june 7, 2016 in accordance with. Read the display and compare the resistance on your ohmmeter to the resistance stated on the transformer s data sheet. The following definitions are used in megger ttr test instruments. So for ensuring proper performance of electrical power transformer, voltage and turn ratio test of transformer one of the important tests. Open and short circuit test of transformer electrical4u. If you suspect a bad transformer in a piece of equipment, you can perform a simple test with an oscillator that checks the transformers basic functions. Section 7 of the ansineta standard for acceptance testing specifications for electrical power equipment and systems may be reproduced and used on a cut and paste basis for the particular type of equipment to be tested. C electrical power from one voltage to another voltage keeping the frequency same by.
Complete tests 1 and 2 for each winding of a threephase transformer individually with the remaining windings kept open. Transformer tests eep electrical engineering portal. The first type of test is called output transformer testing, and the second type is called a transformer continuity test. Transformer bushing cts should be tested using the current ratio test method before the transformer has been completely assembled. Power transformer testing testing of power transformers 2. Read the display and compare the resistance on your ohmmeter to the resistance stated on the transformers data sheet. These properties can be used to test the numerical differential protection of any manufacturer as described further in this document. The transformer was immediately taken offline and internally inspected to identify any problems. The purpose of this article is to help a test set operator understand the tests they perform, and hopefully add or re. The ac hv test value should not surpass 75% of the factory test value. In addition to that some transformer tests are also carried out at the consumer site before commissioning. Transformers, dry type, aircooled, lowvoltage, large. The test connection arrangement is shown in figure 2 c. Transformer stability test procedure a media to get.
The standard megger testing equipment is used, the line terminal of which is connected to the winding or core bolt under test. Mainly two types of transformer are done by manufacturer before dispatching the transformer mainly 1 type test of transformer and 2 routine test. Aug 20, 20 build your own current limiter for protection when repairing and testing electronic equipment duration. 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. Pdf transformer testing type test and routine test of.
The open circuit test of the transformer is one of the type test of transformer by which core losses of the transformer are determined. A test set operator connects the leads, pushes the buttons, and records the results. There are several tests that can be done on the transformer. Testing and diagnostics of power transformers brochure 4. The connection diagram for the short circuit test on the transformer is shown in the figure below. Short circuit and open circuit tests on transformer can give us parameters of equivalent circuit of transformer, but they can not help us in finding the heating information. Pdf transformer is a static device which transforms a. Video lecture on open circuit test and short circuit test on transformer of chapter single phase transformer of subject basic electrical engineering for firstyear engineering students. Ensure that all equipment to be tested is properly grounded and treat all highvoltage power equipment as energized until proven otherwise by using the proper lockouttagout procedures. Testing power transformers highvoltage transformers are some of the most important and expensive pieces of. Mlgw began to test each of its transformers for furans in 2009.
Polarity test of transformer its circuit diagram circuit. Testing of power transformers seems like a similar experience. The fact that some differences between responses are inevitable and must be allowed e. What is the megger test procedure for transformers. In this book we have laid down important aspects on transformer. Apply the 440 vac supply from hv side of the transformer in such way that primary cts are included in the circuit. Routine tests and type tests of transformers electrical4u.
The article is organized as per the neta standards for easy reference. Short circuit and open circuit test in single phase transformer. The transformer testing performed before commissioning the transformer at the site is called the precommissioning test of transformer. Build your own current limiter for protection when repairing and testing electronic equipment duration. This test is similar to tests 1 and 2, but as applied to a three phase transformer for phase identification and phase continuity check. So transformer ratio test is an essential type test of transformer. If you suspect a bad transformer in a piece of equipment, you can perform a simple test with an oscillator that checks the transformer s basic functions. Some tests are done at manufacturer premises before delivering the transformer. A stepdown transformer is one that reduces the input voltage. Installation measurements should be filed for future reference 2. In addition some other tests are also carried out by the consumer at site before commissioning and also.
The oscillators ac signal tests the integrity of the primary and secondary windings. Transformer nameplate voltage, tnv labelled linetoline voltage for a winding defined on transformer template. Periodically monitoring and preventive maintenance can detect the defects before major damage has been occurred. Sumpners test or back to back test on transformer is another method for determining transformer efficiency, voltage regulation and heating under loaded conditions. Ms excel spreadsheet electrical engineering portal. Transformer ct testing as test equipment becomes more sophisticated with better features and accuracy, we risk turning our field personnel into test set operators instead of skilled field service technicians. Before proceding with transformer measurements the test engineer will become familiar with the safety rules of section 2. A 40yearold transformer showed a degree of polymerization of 260 in early 2010 during testing, with estimated remaining life at 19 percent.
1674 537 1190 91 886 633 1650 1018 291 465 1576 970 649 1047 151 1035 438 190 177 121 601 107 123 1594 1102 1185 1094 1589 1590 1036 1437 1062 1013 841 1442 1050 956 1483