What is PI test of Transformer?

Question

Accepted Answer

PI test is a type of transformer testing that measures the insulation resistance and polarization index.

PI test is performed to determine the condition of insulation in transformers.
It involves measuring the insulation resistance and polarization index of the transformer.
The insulation resistance is measured by applying a DC voltage to the transformer winding and measuring the current.
The polarization index is the ratio of the insulation resistance at 10 minutes to the insulation resistance at 1 minute.
A high PI value indicates good insulation condition, while a low value indicates poor insulation condition.
PI test is usually performed during routine maintenance of transformers.
It helps in identifying potential faults in the transformer insulation before they become major issues.

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