Answer / k.prakashchandra

PIR -preinsertion resistor.It is connected in parallel to
the main interrupter which in series connects the PIR at the
time of beginning of opening of contacts to limit the
current to be interrupted.The PIR is in parallel with
contacts when the breaker is closed,in series at start of
opening and completely disconnected after opening.

Answer / t r sastry

PIR - Pre-insertion resistor

PIR is used for safe handling of the transients in EHV
switching operations. PIR will be active only for few milli
seconds during switching after which it will be out of
circuit

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