Patent ID: 8212423

Claim:
A switching controlgear of circuit breaker which causes a circuit breaker to open or to close at a desired phase of power system voltage or main circuit current, comprising: estimated circuit breaker operation time calculation means for constantly and repeatedly calculating an estimated opening operation time or estimated closing operation time of the circuit breaker according to a state of the circuit breaker; switching command signal output delay means for delaying an output timing of an opening command signal or closing command signal to the circuit breaker so as to cause the circuit breaker to open or to close at the desired phase when the opening command signal or closing command signal is detected; switching control signal output time calculation means for calculating a switching control signal output time, which is a delay time from a timing of detecting the opening command signal or closing command signal to a timing of that the switching command signal output delay means outputs the opening command signal or closing command signal to the circuit breaker; reference point detection means for periodically detecting a reference point of the power system voltage or main circuit current; synchronization delay time calculation means for calculating synchronization delay time using the reference point detected by the reference point detection means as a reference; and reference point-command signal interval time calculation means for calculating a reference point-command signal interval time which is time from the reference point to a detection timing of the opening command signal or closing command signal, wherein: the synchronization delay time calculation means calculates the synchronization delay time using the reference point as a reference so that the circuit breaker opens or closes at the desired phase after the total time of the synchronization delay time and estimated opening operation time or the estimated closing operation time of the circuit breaker calculated by the estimated circuit breaker operation time calculation means is elapsed, the switching control signal output time calculation means calculates the switching control signal output time based on the time length relationship of the reference point-command signal interval time and the synchronization delay time calculated by the synchronization delay time calculation means, and the switching command signal output delay means outputs a delay-controlled opening command signal or a delay-controlled closing command signal to the circuit breaker after the switching control signal output time, which is the latest, is elapsed when an opening command signal or closing command signal is actually detected.