Patent attributes
A leakage detection circuit includes a branch having a body ground, a protective resistance, a switch element, a detection resistance, and a variable power supply that are coupled in series. A low voltage side of the variable power supply is connected to a negative electrode of a power supply device that is a subject for observation. Under control of the computer, the variable power supply outputs the voltage of 0 (zero) volt for detecting the leakage on a high voltage side and the voltage of 10-odd volts for detecting the leakage on the low voltage side. A leakage current is determined by amplifying a voltage across the detection resistance. A reference potential is not the body ground but the negative electrode of the power supply device, making it possible to configure the circuit in a relatively simply by using one detection circuit with one switch element having high voltage resistance.
