go to the Air-insulated switchgear product page Aditya asked on May 29th, 2015 in Air-insulated switchgear

How will we confirm that Pre-insertion resistor (PIR) of 420 kV Circuit breaker opened after closure of main contacts?

Christian Cingolani, Global Product Marketing Manager LTB

ABB's answer

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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1 Comment

  • Niclas Wetterstrand commented on Oct 1st, 2015

    Pre-insertion resistor timing is measured with timing channels compatible with the higher resistance.
    Dynamic Resistance Measurment (DRM) is used to dertermine the length of the arcing contact.
    The challenge to measure timing of a contact in a circuit with sometimes in the kohm range is that with interference in substations which will affect the results.

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  • Helene Hedlund

    Helene Hedlund

    Global Product Manager LTB

    High Voltage Products

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