ARC FAULT DETECTOR WITH PROTECTION AGAINST NUISANCE TRIPS AND CIRCUIT BREAKER INCORPORATING SAME

摘要

An arc fault detector of the type which generatesa trip signal when a time attenuated accumulation of pulsesproduced each time an arc is struck reaches a selectedvalue, includes a pulse conditioner which discriminatesagainst false trips induced by phenomena such as tungstenbulb burn out and turn on of a cold tungsten bulb controlledby a dimmer. The pulse conditioner includes a zener diodewhich limits the amplitude of the pulses applied to theintegrator, and stretches all of the pulses to reduce thevariation in pulse duration. The latter can be accomplishedby a peak detector which stretches pulses which reach thezener limit to a duration of at least about a half cycle.