| 摘要 |
PURPOSE: To provide a ground accident relay and a ground accident relay device which can break only an accident phase, judging the direction of an accident correctly at a high-resistance grounding accident. CONSTITUTION: The ground direction relay, which is constituted to derive the relay output, judging the direction of an accident, using a plurality of electrical quantities concerned with the voltage and currents taken in from a power system to be protected, comprises a first means which gets a zero-phase current from the current taken in from the power system to be protected, and a second means which compares the phase of the zero-phase current obtained from the first means with the phase of phase voltage or voltage equivalent to it and judges whether it is within a predetermined reference value or not and outputs an applicable voltage phase as an accident phase, judging that a forward ground accident is occurring in case that it is within the reference value.
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