Page 29 - Practical Power System and Protective Relays Commissioning

Introduction to Testing and Commissioning of Power System Chapter | 3 25

3.2.2 Electrical Tests
An electrical test can include any of the following:

1. Core insulation resistance.
2. Winding insulation resistance.
3. Winding resistance at all taps.
4. Tan δ of the transformer bushing test.
5. Polarity and vector group tests.
6. Turns ratio test.
7. Tap changer local and remote operation test.
8. Fan groups 1 and fan group 2 (Each transformer has a two groups of
fans for cooling) running test for rotation and operation test.
9. Bushing current transformer tests.
10. Oil sample breakdown high voltage test.

These tests are explained in detail in the following chapters.

3.3 SURGE ARRESTOR TEST
Visual checks should include the nameplate, all connections, earthing and all
related items as per instruction manual.

3.3.1 Visual Checks
Visual checks for nameplate, connections, earthing and all related items as
per instruction manual.

3.3.2 Electrical Tests
An electrical test can include any of the following:
1. Insulation resistance test.
2. Tan δ test.
3. Leakage current measurement.

3.4 CURRENT TRANSFORMER COMMISSIONING TESTS
3.4.1 Visual Checks

Check visually for any damage or craking or oil leakage in the CT.

3.4.2 Commissioning Electrical Tests

An electrical test can include any of the following:
1. Insulation resistance test.
2. Winding resistance test.