| 摘要 |
PROBLEM TO BE SOLVED: To enable detecting the failures of a breaker in a power converter. SOLUTION: A fault-detecting device 22 is equipped with a current abnormality detecting circuit 50 for detecting abnormalities, when one from among summed values of current quantities of the respective two phases out of three- phase currents of a three-phase AC power source becomes lower than or equal to a reference value 150, a current value detecting circuit (current value detecting means) 51 which measures the respective mean values of three-phase currents of the AC power source and determines a current existing state, when the current quantity of any phase is larger than or equal to the reference value 150, and an AND circuit 52, a delay circuit 53 and a latching circuit 54 for detecting abnormality of fuses Fu, Fv, Fw, when the detecting circuit 50 detects abnormality and a state in which detecting means 51 determines that the current exists continues.
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