Patent ID: 7075311
Filing Date: 2006-07-11
Classification: G01R

Abstract:
1. An insulation detecting device for a non-grounded power source, comprising: a capacitor; a DC power source, insulated from a ground potential part; a voltage detecting unit, detecting a voltage across the capacitor; a first switching unit, connecting the capacitor to the DC power source in series for a first preset time shorter than a time taken for completely charging the capacitor; a second switching unit, connecting the capacitor between a positive terminal of the DC power source and the ground potential part in series for a second preset time; a third switching unit, connecting the capacitor between a negative terminal of the DC power source and the ground potential part in series for the second preset time; a fourth switching unit, connecting the voltage detecting unit to the capacitor after the first to third switching units are turned off; and a computing unit, estimating a voltage across the power source based on a detection voltage that is detected by the voltage detecting unit after the first switching unit is turned off, and computing insulation resistances of the power source to the ground potential part based on the estimated voltage and each detection voltage that is detected by the voltage detecting unit after either of the second and third switching unit is turned off.