| 摘要 |
PROBLEM TO BE SOLVED: To obtain a fault detecting device which can detect the fault of a three-phase capacitor with accuracy, even if the power supply voltage of each phase or the capacitance of the internal capacitor of the capacitor fluctuates. SOLUTION: A fault detecting device for three-phase capacitor is provided with current detecting circuits 5a, 5b, and 5c, which detect the currents inputted to each phase of a three-phase capacitor 1, a signal-processing circuit 6 which detects the fault of the capacitor 1 from the signals outputted from the circuits 5a, 5b, and 5c, and a storage circuit 7 which stores the computed results of the circuit 6. The signal-processing circuit 6 is constituted to discriminate and detect the fault of the capacitor 1 by calculating the ratio between the current values of each two phases in the three phases during the operation based on the signals outputted from the circuits 5a, 5b, and 5c, and at the same time, by comparing the data with the ratios which are acquired during the normal operation of the capacitor 1 and stored in the storage circuit 7.
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