GROUND FAULT TRIP MODE NETWORK FOR STATIC TRIP CIRCUIT BREAKERS

摘要

41PR-6102GROUND FAULT TRIP MODE NETWORKFOR STATIC TRIP CIRCUIT BREAKERSABSTRACT OF THE DISCLOSUREThe secondary currents of plural currenttransformers are applied to a full-wave rectifyingnetwork for developing an overcurrent signal and aground fault current signal; the flowing in a circuitpath embraced by the toroidal core of a miniaturecurrent transformer. A transformed ground faultcurrent signal appearing in the multi-turn secondarywinding thereof is applied to a ground fault trip modenetwork operating to measure the signal magnitudeagainst an adjustably established, continuous groundfault trip-time curve including a vertical pick-upcurve portion and a sloping inverse time (r2t) delayportion which terminates in a selected one of pluralhorizontal, fixed time delay portions pursuant toissuing an appropriately delayed ground fault tripsignal. Provisions for zone selective interlockingbetween upstream and downstream breakers are alsodescribed.