Arc fault detector responsive to average instantaneous current and step increases in current and circuit breaker incorporating same

Abstract From the Canadian patent

An arc fault detector includes an average instantaneous current generator which averages the current over the fundamental period and produces a substantial output only where there are substantial variations in waveform between half cycles which is indicative of an arc. To discriminate over inrush currents a pulse generator generates a pulse in response to the step increase in current caused by striking of an arc. An output circuit generates an arc signal when the time attenuated accumulation of pulses occurring in half-cycles in which the average instantaneous current is above a selected threshold reaches a predetermined level. To further discriminate over dimmers during turn on of a cold …