Types of Transformer Testing

Types of Transformer Testing

Each transformer has its own specification and performance confirmed by some different tests.

Before delivering the transformers to customers, it also is tested and acceptable in the factory. Besides, there are some tests are done on the user’s site.

Types of Transformer Testing

Tests were done at the factory

  1. Routine tests
  2. Type tests
  3. Special tests

Tests were done at the site

  1. Pre-commissioning tests
  2. Periodic/condition monitoring tests
  3. Emergency tests

Routine Tests of Transformer

Routine tests of transformers are mainly carried out with the aim of confirming the operational performance of the individual unit in a production lot. Every unit is done the Routine tests.

Type Test of Transformer

To see whether the transformer meets the customer’s specifications and design expectations, some different tests have to be carried out on manufacturer premises. Some tests are mainly for confirming the basic design expectation of that transformer. These tests are carried out in a prototype unit, not in all manufactured units in a lot. The main and basic design criteria of a production lot are confirmed by the Type test of the transformer.

Special Tests of Transformer

Special tests of the transformer are carried out under customer requirements to get useful information to the customer during commissioning or maintenance of the transformer.

Pre-Commissioning Test of Transformer

Before actual commissioning of the transformer at the site, The transformer has to go through some other tests, performed on it. These tests are called the pre-commissioning tests of the transformer. They are carried out to assess the condition of the transformer after installation and compare the test results of all the low voltage tests with the factory test reports.

Type tests of transformer include:

  1. Transformer ratio test
  2. Winding resistance test of transformer
  3. Transformer vector group test
  4. Measurement of impedance voltage/short circuit impedance (principal tap) and load loss (Short circuit test)
  5. Measurement of no-load loss and current (Open circuit test)
  6. Dielectric tests of transformer
  7. Measurement of insulation resistance
  8. Temperature rise test of transformer
  9. Vacuum tests on tank and radiators
  10.  Tests on on-load tap-changer

Routine tests of transformer include

  1. Transformer ratio test
  2. Winding resistance test of transformer
  3. Transformer vector group test
  4. Measurement of impedance voltage/short circuit impedance (principal tap) and load loss (Short circuit test)
  5. Measurement of insulation resistance
  6. Measurement of no-load loss and current (Open circuit test)
  7. Tests on on-load tap-changer.
  8. Dielectric tests of the transformer.
  9. Oil pressure test on the transformer to check against leakages past joints and gaskets

Routine tests and type tests have similar test items except for temperature rise and vacuum tests. The oil pressure test on the transformer to check against leakages past joints and gaskets are included.

Special Tests of transformer include

  1. Short-circuit test
  2. Dielectric tests.
  3. Measurement of the zero-sequence impedance of three-phase transformers
  4. Measurement of the harmonics of the no-load current.
  5. Measurement of acoustic noise level
  6. Measurement of the power taken by the fans and oil pumps.
  7. Tests on bought-out components/accessories such as Buchholz relay, temperature indicators, pressure relief devices, oil preservation system, etc.

 

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