| 摘要 |
An insulation resistance drop detector includes a pulse generator that applies a pulse signal to a series circuit in which a detecting resistor, a coupling capacitor, and an insulating resistance are serially connected. In a state where the pulse signal is applied to the series circuit, control circuit detects a pulse-like divided voltage occurring at a node by a voltage detecting circuit via a bandpass filter, to thereby sense a drop of an insulation resistance. Further, the control circuit senses a failure of the insulation resistance drop detector itself when the voltage detected by the voltage detecting circuit is maintained at least at a prescribed voltage exceeding a plurality of cycles of the pulse signal. Thus, the insulation resistance drop detector having a failure self-diagnosis function is realized by a simple configuration.
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