Answer / raghavendran.r

CT works on subtractive polarity.It is essential for
reducing the flux build up in the CT secondary, otherwise
immense flux build up will cause insulation burn out.Also
the CT secondary should not be left open.

The other power transformers work on additive polarity
principle.Hence it is required to check the polarity.

Answer / anand

Polarity Test is needed for Ct's because if polarities are not properly matched (Subtractive generally),relays which were based on connections of ct will maloperate(E/L Stability)and hence the lines will unnecessary trip....

Answer / naresh chandra jha

to check that mmf is in additive polarity or subtractive ,
polarity polarity test is important because in case of
additive polarity (primary mmf and secondary mmf in same
direction direction ) insulation may get damage .

While performing stability test of differintial cts how to know the voltage and current on both side of the transformer?

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