Patent ID: 7292042

Claim:
A ground fault detector for determining a ground fault in a circuit connected to a power source, the ground fault detector comprising: a capacitor, one side of which is connected to an output of the power source; a pulse generator that applies a pulse signal to a measurement point on an opposite side of the capacitor, the pulse signal generated at a oscillation frequency; a voltage detecting part that detects the voltage amplitude generated at the measurement point when the pulse signal is applied to the measurement point; and a controller operable to detect an occurrence of a ground fault in the circuit based on a change in the voltage amplitude as compared to an original voltage amplitude of the pulse signal, to change the oscillation frequency of the pulse signal, and to determine a cause of the occurrence of the ground fault by comparing the voltage amplitude detected when the pulse signal is generated at the oscillation frequency to a voltage amplitude resulting from generation of the pulse signal at a changed oscillation frequency.