A simple evaluation method of the thermal interruption limit of power circuit breakers

In this paper, a simplified test method has been proposed and implemented for evaluating the thermal interruption capability of the power circuit breakers. In this method, the influences of the arc voltage of the auxiliary breaker on the evaluation of the thermal interruption limit of the circuit breaker can be eliminated. To validate the proposed test circuit, a series of experiments have been carried out on a 24-kV SF6 gas circuit breaker with rated short circuit of 25 kA and the successful interruption zone in terms of the time derivative of the current before current zero (di/dt) and rate of increase in recovery voltage (dv/dt) has been determined.