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Leakage detection apparatus and motor car

  • US 6,919,726 B2
  • Filed: 12/02/2002
  • Issued: 07/19/2005
  • Est. Priority Date: 12/27/2001
  • Status: Expired due to Fees
First Claim
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1. A leakage detection apparatus for detecting the presence or absence of leakage between a high-voltage circuit and a low-voltage circuit, comprising:

  • a signal generator for generating a signal whose frequency is set variably;

    a resistant element for attenuating the signal from the signal generator in cooperation with an insulation resistor between the high-voltage circuit and the low-voltage circuit;

    a capacitive element for capacitance-coupling one end of the resistant element to the high-voltage circuit;

    a low-pass filter whose cut-off frequency is set variably so as to pass a signal with a frequency set in the signal generator, for attenuating a high-frequency component via the capacitive element to be superimposed on the signal via the resistant element;

    a leakage detection portion for comparing an amplitude level of a signal via the low-pass filter with a predetermined threshold value, and detecting the presence or absence of leakage between the high-voltage circuit and the low-voltage circuit; and

    a control portion for setting the signal frequency of the signal generator and the cut-off frequency of the low-pass filter after startup of the low-voltage circuit and before startup of the high-voltage circuit to be higher than those after startup of the high-voltage circuit.

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