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Medium-sensitivity three-phase earth leakage circuit breaker and earth leakage alarm device to prevent inconvenience unnecessarily blocked by instantaneous distortion waveforms by applying a time-order comparison algorithm in the instantaneous earth leakage current
Medium-sensitivity three-phase earth leakage circuit breaker and earth leakage alarm device to prevent inconvenience unnecessarily blocked by instantaneous distortion waveforms by applying a time-order comparison algorithm in the instantaneous earth leakage current
The present invention relates to a three-phase earth leakage breaker and a leak alarm, and in particular, it does not operate for a shorter instantaneous capacitive leakage current (from 0.1 cycle to 3 cycles) within the rated interruption time (0.1 seconds or less, 6 cycles or less). For continuous leakage current longer than this, it is related to an unnecessary operation-preventing medium-sensitivity 3-phase earth leakage breaker and leakage alarm that operates normally within 0.1 seconds (within 3 cycles to 6 cycles). To this end, the present invention operates unnecessarily even in the instantaneous capacitive leakage current (within about 0.1 cycle within 3 cycles) generated by the instantaneous distortion waveform in a three-phase earth leakage breaker whose rated operation time is cut within 0.1 seconds (6 cycles). In order to prevent this from happening, the instantaneous leakage current value detected by the zero-phase current transformer is sampled at high speed several times per cycle using a microcomputer with a high-speed AD converter, and the leakage current value is read, about 50% ~ 70% of the rated leakage current cutoff value. %, and when it exceeds the set value, the values are compared sequentially for each one cycle before and after. If the values of both cycles exceed the set value, the values of both cycles are compared in time for up to 3 consecutive cycles in that state, and when the set value is exceeded, normal block perform the action
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