
distribution transformers to 95 kV and the liquid-immersed dry type distribution transformers
will be covered by 10 CFR Part 431 on January 1, 2010.
Transformer Tests
A number of tests are required to physically determine the electrical characteristics of power
and distribution transformers. Many of those tests are indicated below [7]:
1. Resistance
2. Ratio
3. Polarity and voltage vector relations
4. No-load loss and exciting current
5. Impedance loss and impedance voltage
6. Temperature tests (heat run)
7. Dielectric tests
Procedures for transformer testing are contained in IEEE C57.12.90, IEEE standard test code
for liquid-immersed distribution, power ...