Guidelines to power transformer type, routine and special tests

Introduction to methods

The methods used during tests and measurements of the Power Transformers, test and measurement circuits, calculations and evaluation criterias are included in this manual. At the end of this manual, BEST Balıkesir Transformer Factory laboratory hardware and measurement and test equipment are listed.

For insulation levels of transformers, electrical characteristics and evaluation, please refer to national and international standards and customer specifications.

Tests and evaluation definitons are listed below:

Routine Tests:

Routine tests are performed during manufacturing on all transformers after the active part assembly completed and according to TS 267, IEC 76 etc.

1. Measurement of winding resistance
2. Measurement of voltage ratio and check of phase displacement
3. Measurement of short-circuit impedance and load loss
4. Measurement of no-load loss and current
5. Dielectric tests
6. Separate source AC withstand voltage test
7. Induced AC voltage test
8. Partial-discharge measurement
9. Tests on on-load tap-changers

Type Tests:

Type tests are performed upon customer request.

1. Temperature-rise test
2. Lightning-Impulse tests

Special Tests:

Special tests are performed upon customer request.

1. Switching impulse voltage test
2. Measurement of dissipation factor (tanδ) and capacitance
3. Measurement of zero sequence impedance(s)
4. Determination of sound level
5. Measurement of harmonics of the no-load current
6. Measurement of insulation resistance

Tests performed on power transformers can be generally classified as follows: Tests during manufacturing, routine tests, type tests, special tests, acceptance tests, site tests, defect analysis / identification and tests before maintenance.