GROUND FAULT LOCATION SYSTEM AND GROUND FAULT DETECTOR THEREFOR

摘要

A ground fault location system (10) is used in a multi-phase ungrounded or high-impedance grounded power network (11). A signal generator (14) is coupled to the network (11) at a first location and generates for each network phase an individual non-DC voltage signal between such phase and ground. A ground fault detector (16) is coupled to the network (11) at a second location and has a summing device (24) and an annunciator (28). The summing device (24) is coupled to all of the phases of the network (11) at such second location, sums any current passing therethrough, and produces a sum signal. The annunciator (28) receives the sum signal and provides an indication when such signal is non-zero. Each phase of the network (11) at the second location has a distribution current passing therethrough, the sum thereof normally being substantially zero and resulting in a substantially zero sum signal and the lack of an indication from the annunciator (28) based on such distribution currents. When the second location is on a path between the first location and a ground fault, the individual voltage signal on at least one of the phases generates a fault current thereon through such path and results in a non-zero sum signal and an indication from the annunciator (28). When the second location is not on such path, none of the individual voltage signals generates a fault current on any phase through such path, resulting in a substantially zero sum signal and the lack of an indication from the annunciator (28).