| 摘要 |
PROBLEM TO BE SOLVED: To detect the initial state of ground fault in which a ground current less that a rated sensible current flows, by an operation test of an earth leakage circuit breaker. SOLUTION: This earth leakage circuit breaker for a single phase comprises an interruption part 5 connected to a main circuit 2, a zero phase-sequence current transformer 6, a leakage detection part 7, a trip coil 8 of the interruption part, and a leakage test circuit 10. Two test coils 11A, 11B parallel- connected to the main circuit via test switches 13A, 13B are provided as current exchanging means for forwardly/backwardly reversing test current flowing through the test coils. The test current is set up to fall within the range of more than one time and less than two times the rated sensible current of this earth leakage circuit breaker, testing is performed two times by alternately pressing the test switches 13A, 13B during the operation test of the earth leakage circuit breaker, and if the interruption part is opened in either of the two times of testing, it is recognized that a ground fault current less than the rated sensible current is flowing.
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