In 400KV Switchyard, we have used Circuit Breaker With PIR,
what is the significance of PIR & why they'r used?

Answer Posted / 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.

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