PREDICTIVE CONTROL CIRCUIT AND METHOD FOR CIRCUIT INTERRUPTER

摘要

A control circuit and method are provided for a circuit interrupter that predicts the occurrence of fault-current zero crossings. This prediction is utilized to control the operation of a circuit interrupter at a desirable point in the periodic wave form of t he fault current. For example, the control circuit is useful to control a synchronous interrupter by accurately generating a trip signal to the synchronous interrupter for operation in the vicinity of the zero crossing of the current wave form. In a preferred arrangement, the control circuit utilizes the quotient of a sensed current signal and the time rate of change of the sense d current signal. In one specific arrangement for circuit environments that might include conditions that could lead to false results, the time rate of change of the quotient is utilized to provide a control signal.