The pre-insertion resistors (PIR) of a 420 kV live-tank circuit breaker is closed as long as the breaker is closed. The current flow is through the main contacts as the resistance in this circuit is about 10 000 times lower.
The pre-insertion resistors are opening before the main contacts during opening and closing before the main contacts during closing.
If you would like to measure the pre-insertion resistor timings you need to have dynamic resistance measurement or isolate the pre-insertion resistor from the main circuit.
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