Patent ID: 7560935

Claim:
A ground-fault resistance measurement circuit which measures a resistance between a charge section insulated from a conductive frame body of an electrical apparatus and the frame body, comprising: a capacitor which is connected between the charge section and the frame body; a first switch which opens and closes a connection path between the charge section connected to the capacitor and the capacitor; a charging power-source section which outputs a predetermined set voltage for charge; a charging unit which charges the capacitor, using the predetermined set voltage output from the charging power-source section; a voltage measurement section which measures a charging voltage of the capacitor; a discharge control section which closes the first switch after charging the capacitor by the charging unit; and a calculation section which calculates a resistance value between the charge section and the frame body, based on a change in the charging voltage measured by the voltage measurement section after closing the first switch by the discharge control section.