Motor winding leakage monitor

摘要

A low voltage power supply powers a high impedance, high voltage dc supply. An electronic switch serves to automatically connect the high voltage output to the windings of a motor when the motor is non-operating. A lead connects from the frame of the motor to a sense resistor connected to the high voltage system ground. A plurality of variable threshold comparators is connected across the sense resistor. Leakage of the motor windings insulation results in a current flow through the sense resistor producing a voltage drop proportional to the leakage. Each comparator is adjustable to produce an indication of a value of leakage resistance at which the comparator produces an output.