| 摘要 |
PROBLEM TO BE SOLVED: To provide an insulation resistance lowering detecting apparatus capable of accurately detecting insulation resistance deterioration at high speed taking it into account the influence of stray capacitance. SOLUTION: Since the resistance value of an insulation resistance 12 is considered to be very large at the beginning of disposition, the stray capacitance 13 can be calculated according to the measured values of the input side voltage Vin and the output side voltage Vout. The output side voltage Vout corresponding to the calculated value of the stray capacitance 13 is calculated from the calculated value of the stray capacitance 13, the input side voltage Vin and the detected resistance value of the insulation resistance 12 (e.g. resistance value a little larger than the resistance value when the insulation resistance is deteriorated), and the calculation result is taken as reference data. After that, during the operation of the insulation resistance, the output side voltage Vout is measured, and the voltage data and the reference data are compared. Since the stray capacitance 13 is considered to make no change after disposition, when the large and small relationship between the voltage data and the reference data is reversed, the actual resistance value of the insulation resistance 12 is regarded to be lowered than the detected resistance value.
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