Testing of transformer pdf

Common electrical tests on power transformers omicron. A test set operator connects the leads, pushes the buttons, and records the results. Transformers regulate the voltage in circuits, but in some cases these can go. It is a good idea to remove all as a safety precaution to prevent backfeeding dangerous voltages into the system during testing.

For details, visit our transformer application page. Page 1 of 14 standard work practice sp0504 ver 4 ergon energy corporation limited abn 50 087 646 062. Core excitation current test this test is normally performed with an insulation power factor test set. In this paper, the different types of transformer testing are mentioned. To learn more, visit our commissioning routine diagnostic tests page. Build your own current limiter for protection when repairing and testing electronic equipment duration. Transformers are an electrical component that transmit electrical energy between at least two circuits. This test ensures that the transformer will provide the proper stepup or step down in voltage. Power transformer testing swp check this is the latest process zone version before use. A guide to transformer winding resistance measurements bruce hembroff, cet, manitoba hydro matz ohlen, megger sweden peter werelius, megger sweden abstract. C electrical power from one voltage to another voltage keeping the frequency same by. Standard for acceptance testing specifications for.

Put your ohmmeter on its lowest scale and after removing the plastic sheaths from the conductors, touch its leads together to verify that it is ready for testing. The voltage ratio of a transformer is the ratio of the rms terminal voltage of a. Following is an approximate sequence for transformer testing. To test a transformer, however, you will need to disconnect it from the circuit before doing anything else. The ac hv test value should not surpass 75% of the factory test value. Drytype transformer testing introduction the primary concern with all transformers and also the key indicator of life expectancy is the condition of the insulation system. Testing recommendations vary through the life of a transformer and relate to the circumstances under which the testing is being performed. The quality of a transformer is of utmost importance for safety, industrial and financial reasons. Steel itself is a conductor, and changing lines of magnetic flux also induce a voltage and current in this conductor. Transformer book is still in demand is a tribute to the publishers and to the authors who have carried the torch to light our way for 75 years. That means routine tests of transformer include all the type tests except temperature rise and vacuum tests. Home download center electrical engineering books and technical guides power substation guides testing procedures for power transformer ms excel spreadsheet ms excel spreadsheet this ms excel spreadsheet is actually detailed instruction for each procedure necessary for. For confirming the specifications and performances of an electrical power transformer it has to go through numbers of testing procedures. There are a multitude of checks and tests performed as a transformer is being assembled at a substation.

Some of the process failures that can be detected by a productionline hipot test include, a transformer wound in such a way that creepage and clearance have been reduced. The transformer was immediately taken offline and internally inspected to identify any. Pdf transformer is a static device which transforms a. Vector group test of power transformer electrical4u. The ac hipot test is used to assess transformer windings condition.

Before conducting a transformer winding resistance test, it is important to observe all safety warnings and take proper precautions. Inspect transformer and parts for shipping damage and moisture. We also offer solutions for testing bushingtype current transformers for measurement deviations or phase faults. In this paper, various intelligence techniques are used to test transformer. Verify correct operation of transformer withdrawal mechanism and grounding operation. The book represented the collective wisdom of over 100 years of testing power transformers. Various influences can impact the expected lifetime throughout a transformers lifecycle. Understanding insulation resistance testing pdf 0712 technical assistance 800 34391. Oil pressure test on transformer to check against leakages past joints and gaskets. Testing of power transformers seems like a similar experience.

Transformer testing type tests and routine tests of. 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. Transformer oil testing is a proven loss prevention technique which should be a part of any condition based predictive maintenance program. Power transformer testing testing of power transformers 2. Transformer testing type test and routine test of transformer electrical4u. After the mess was cleared, it was determined the nameplate data was incorrect, showing the wrong polarity. Ppt transformer tests powerpoint presentation free to. Pdf transformer testing type test and routine test of. Morgan lacey in 1925, based on a series of pamphlets entitled transformer abstracts that were. Power transformers are the central hub in the field of energy distribution and transmission. The transformer turns ratio test is used to make sure that the ratio between the windings of the primary and secondary coils follow the proper specifications. Routine tests and type tests of transformers electrical4u. The priciples of routine, type and special tests are however. Some tests are done at manufacturer premises before delivering the transformer.

Mainly two types of transformer testing are done at manufacturer premises type. The oil pressure test on transformer to check against leakages past joints and gaskets is included. Ac voltage is preferable to dc voltage for transformer testing because ac voltage simulates the internal stress that the transformers face during operating conditions. The transformer testing performed before commissioning the transformer at the site is called the precommissioning test of transformer. The installation and testing of the transformer verifies its condition at the time it is ready for service as well as forming the baseline or signature tests for all future maintenance and later condition assessment or analysis. This will prevent inaccurate readings and ensure your own safety. The preference is that all large power transformers 1 mva be tested with ttr test set. Testing of transformer or insulating oil 1 transformer oil, a type of insulating and cooling oil used in transformers and other electrical equipment, needs to be tested periodically to ensure that it is still fit for purpose. Mainly two types of transformer are done by manufacturer before dispatching the transformer mainly 1 type test of transformer and 2 routine test. Transformer is one of the important equipment in power system. In 2003, abb compiled all its knowledge in a book titled testing of power transformers. In addition some other tests are also carried out by the consumer at site before commissioning and also periodically. In this book we have laid down important aspects on transformer. When the pt is withdrawn ensure that there is no longer any connection with the primary electrical system.

In this book we have laid down important aspects on transformer testing in order to enhance the understanding of the testing procedures and its outcome. Transformer testing has developed considerably over the past years. In this paper testing of distribution transformer is considered. 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. 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. Transformers, dry type, aircooled, lowvoltage, large. With our testing system, you can use a single device to determine all of these parameters in an easy way. 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. Voltage is applied to the high voltage windings, one at a time. The phase sequence or the order in which the phases reach their. 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 voltage. The different tests conducted in a distribution transformer as per the standards are discussed below. The measuring equipment differens from those explained herein.

Testing power transformers test procedures and equipment used for the testing of large power transformers at abb oy, power transformer, vaasa works are dealt with in the following sections. Testing of three phase power transformer ijireeice. The vector group of transformer is an essential property for successful parallel operation of transformers. Namely, if testing is based on injecting only one sequence current component at the time on both ct inputs of the transformer differential protection, simple testing procedures can be derived, which are more intuitive, less complex and straightforward than existing phasewise testing procedures. Scribd is the worlds largest social reading and publishing site. As such, their condition is critical for reliable, faultfree operation. The following sections of the ansineta standard for acceptance testing specifications for. It evolved from the simple gonogo verdict into a sophisticated segment within transformer manufacturing.

For dry type transformers, the insulation system consists of the cast resin winding and core insulation. 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. Mlgw began to test each of its transformers for furans in 2009. The ecodesign directive of the european union and the related regulation 5482014 for transformer losses requires manufacturers to publish on the internet information on rated power, load loss, noload loss and weight and type of the major components of typical transformers, which are.

Timeresistance testing method this method is fairly independent of temperature and often. So, testing the transformer is pretty serious issue. A 40yearold transformer showed a degree of polymerization of 260 in early 2010 during testing, with estimated remaining life at 19 percent. All of these factors affect the amount of testing necessary to certify that a transformer is ready to be energized and placed in service. Field testing of a power transformer before putting into service 50mva. The resulting overloads of grid sections can lead to farreaching supply and production failures. Such a failure could result from a new operator in the winding department the hipot test a versatile test. Once you have completed the testing, you can also demagnetize the transformer. Before proceding with transformer measurements the test engineer will become familiar with the safety rules of section 2. Testing and diagnostics of power transformers brochure. There are various test required on transformer to conform performance of transformer. To understand the nature of ratio testing it is important to understand the applicable definitions.