Patent ID: 8878544

Claim:
An electric leakage sensing apparatus comprising: a coupling capacitor having one end connected to a DC power supply; a pulse generator that supplies a pulse to the other end of the coupling capacitor; a voltage detector that detects a voltage at the coupling capacitor charged by the pulse; an electric leakage determination part that compares the voltage detected by the voltage detector to a threshold value, and makes a determination of existence or non-existence of an electric leakage of the DC power supply based on a comparison result; and a booster circuit that applies a boosted pulse voltage to the coupling capacitor, wherein the pulse generator converts an output voltage of the booster circuit into the pulse voltage, the voltage detector includes an offset voltage generating circuit that generates an offset voltage, which is lower than the pulse voltage, based on the output voltage of the booster circuit and a calculation circuit that outputs a voltage in which the offset voltage is subtracted from the voltage at the coupling capacitor, and the electric leakage determination part makes the determination of the existence or non-existence of the electric leakage based on the comparison result between the output voltage of the calculation circuit and the threshold value.