Development of synchronous switching controller for gas circuit breakers

Synchronous switching controller (SSC) applied to gas circuit breakers (GCB) has been developed. The SSC is able to open and close the contacts of the GCB at the pre-determined point on wave for minimizing the switching surges. This paper proposes the new controlled switching algorithm to minimize the total delay time and the control error. New algorithm for detecting voltage and current zero crossing points and predicting the next operating time of the GCB is introduced. 145 kV GCB with the SSC installed the proposed algorithm has been verified by various tests. The SSC performed successful operations and the standard deviation from the target point is within 0.5 msec at ambient temperatures from -30 to 60 degrees C for different control voltages. The making tests at voltage zero also works well in a capacitive load circuit at 145 kV and 362 kV ratings.