| 摘要 |
PROBLEM TO BE SOLVED: To overcome the problem, wherein it takes a long time to confirm a voltage rise and diagnose a failure in a relay, since the voltage on the load circuit side is detected by a voltage sensor, in the conventional apparatuses, when the relay is turned on/off. SOLUTION: A first voltage is measured at a measurement point A, when one end of a coupling capacitor Ca is connected to a positive terminal of a DC power supply 2; a rectangular pulsed signal is applied to the measurement point A as the other end of the coupling capacitor Ca; the rectangular pulse signal becomes a first phase, and a second voltage is measured at the measurement point A, when the rectangular pulsed signal has a second phase that is different from the first phase; and the difference between the first and second voltage is obtained. Based on the voltage difference, ground fault detecting system 1 is provided so as to detect ground faults in the DC power supply 2, and failures in the relays 5, 6, 7 are detected, based on a change in the voltage difference when the relays 5, 6, 7 are controlled when they are turned on/off. COPYRIGHT: (C)2008,JPO&INPIT
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