| 摘要 |
The circuit breaker comprises an A/D converter (16) converting analog voltage signals originating from a current detector into corresponding digital voltage signals then sending them to a microcomputer. The latter selects the minimum digital voltage signal from among the said digital signals generated by the converter during a predetermined period. The microcomputer squares the difference values between the values of the digital signals and the specific value selected and accumulates the squared values obtained. The microcomputer counts the number of accumulation operations then divides the accumulated value by the counted value. The microcomputer generates circuit-opening signals after a predetermined time-limiting operation when the RMS value of the operating load current, indicated by the value of the square root, exceeds a predetermined value, these signals opening the main contacts. <IMAGE>
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