Transformer Testing- Type Test| Routine Test

To ensure the performance and compliance of specifications transformer should go through various testing procedures. In general, testing of power transformer can be segregate into two part as on the basis of testings at manufacturer’s factory and testings at site after the delivery of transformer. Generally manufacturer’s perform routine test and type test directly or by the third parties (like STL member testing company), and end users normally perform pre-commissioning and commissioning test. The main testings at manufacturer’s factory includes:


I. Type Test also known as Conformance Test

II. Routine Test

I. Type Test

Type test are also known as Conformance test- mainly complying its specifications. This test confirms the basic design criteria of a transformer of a production lot. Type test are performed to check whether the manufacturing transformers are as per specifications, standards, design and to meets costumer expectations. The transformer has to go through various testing procedures at manufacturing factory. These test are carried out in prototype unit of a lot.


Type tests of transformer shall include various measurements and testing, they are:

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

II. Routine Test

Routine test are carried out for confirming the operational performance of transformer in every individual units of lot. Routine tests procedures are similar to type test except temperature raise test and vacuum test.


Routine Test of transformer shall include;

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

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