| 摘要 |
PROBLEM TO BE SOLVED: To provide a circuit breaker in which the operation current at breaking can be obtained from outside without requiring a separate control power source, and the cause of occurrence of breaking can be distinguished. SOLUTION: A current carrying state memorizing capacitor 170 is provided which memorizes as an electric charge an I<SP>2</SP>t value obtained by an I<SP>2</SP>t calculation means 111 achieved by a microcomputer 110; the accumulated charge in the current carrying state memorizing capacitor 170 is read when the power source of the microcomputer 110 is established; a breaking current conversion means 112 determines whether or not a momentary power stop has occurred on a main conductor coupled to a current detection means 120, based on whether the charge is 0 or not; and based on the determination result, whether an average current value in zones where the current of the main conductor detected by the current detection means 120 is not 0, or a current value right before braking is output outside as a breaking current, is decided. COPYRIGHT: (C)2009,JPO&INPIT
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