Resistance Threshold Method for Accurate and Reliable Both-Sides Grounded Timing Measurements for High-Voltage Circuit Breakers

Resistance-based timing measurement methods promise to overcome the drawbacks of voltagebased methods and allow grounding on both sides of the circuit breaker, which means that all parts exposed to the tester are grounded. In this paper, the resistance-based method of dynamic resistance measurement is used to find the limitations of this method with multiple circuit breaker configurations. This work shows how ground-loop resistance influences the accuracy and reliability of operating timing tests and provides guidance on how to use it depending on the ground connection. In case of a single interrupting chamber circuit breaker, accurate timing tests were conducted for ground resistances as low as 1.3 mΩ during trip sequences on gas insulated switchgear.