Abstract: In the embodiment described in the specification, a fault tolerant motor drive circuit arrangement includes a motor having three stator windings which are electrically isolated and are supplied by separate single phase drive circuits, each having a differential current sensor detecting current in both circuit conductors and an overcurrent sensor in one circuit conductor, along with a ground connection for each circuit having a ground conductor with an overcurrent sensor and a high resistance with a voltage sensor across the high resistance. A monitoring unit receives signals from all of the differential current sensors, overcurrent sensors and voltage sensors to provide indications of the location of insulation faults or incipient faults in the windings.

Abstract: A PCM module arrangement includes a three phase circuit breaker and PCM electronics unit. Each phase of the circuit breaker has a Rogowski coil at the line side and load side contacts in a vacuum bottle and another zero sequence current sensor encloses the load side conductors of the circuit breaker to provide a zero sequence current signal. A PCM electronics unit is provided with phase current measurement signals from the Rogowski coils. The PCM electronics unit provides a direct interface for various signals including a signal from a supervisory control and data acquisition system.