Why is it that polarization index type test is required for MV and HV motors a

Why is it that polarization index type test is required for
MV and HV motors and not for LV motors?

Question Posted / bumbolbee

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Why is it that polarization index type test is required for MV and HV motors and not for LV motors..

The polarisation index is used to check the insulation of
MV and HV motors because it is more accurate. Also it
allows a lower voltage than the working voltage of the
motor to be used. In LV motors the megger test is usually
twice the working voltage. If this was used on an 11kv
motor the megger would need to be 22kv.

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Why is it that polarization index type test is required for MV and HV motors and not for LV motors..

Answer / cr

As we r letting high current pass through the winding using ht megger,there by improving I.R because the heat produced and the ir ratio for 10 to 1 minute should be around 2.otherwise the insulation can be said to be contaminated with foreign meterial , this check is priority for ht motors

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Why is it that polarization index type test is required for MV and HV motors and not for LV motors..

Answer / prashant

because the moror windig is balance or not and winding of the motor is open or not

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