In the earth detector which detects the fact that ground accident occurs with the aforementioned

摘要

PROBLEM TO BE SOLVED: To detect the grounding accident on the side of high-voltage distribution cable, with the circuit on low voltage side of a transformer for power reception, by detecting the reverse-phase components of the fundamental wave of a three-phase AC current detected with a three-phase AC detector, and judging the existence of the occurrence of the grounding accident from this reverse-phase components. ;SOLUTION: When it is judged that a grounding accident has occurred in any of high-voltage distribution cables 3a-3c by grounding judgers provided at network protectors 4Ga-4Gc, breaker controller 4Ea-4Ec give breakers 4Da-4Dc breaking commands. For example, when the high-voltage distribution cable 3a is cut off the bus 1B₁ of a substation 1, the protector breaker 4Da opens to cut off the circuit on high voltage side and the circuit on low voltage side of the transformer 4Ba from each other because the grounding judger of the breaker controller 4Ea detects a grounding accident occurring in the high-voltage cable 3a. As a result, this system can prevent the tidal current of reverse power from occurring on the side of high-voltage distribution cable 3a from side of other sound distribution cables 3a and 3c.;COPYRIGHT: (C)1999,JPO