Patent ID: 8300369
Filing Date: 2012-10-30
Classification: H02H

Abstract:
1. A ground-fault circuit-interrupter (GFCI) system for a polyphase power supply and a main bus circuit coupled thereto, the main bus circuit having a plurality of individual feeder circuits, the GFCI system comprising: a voltage unbalance detection device coupled to all phase lines of the power supply for detecting at least one symmetrical component related to the phase lines, the symmetrical component being indicative of a voltage unbalance of the power supply; a plurality of GFCI units respectively associated with the main bus and each one of the feeder circuits, each of the GFCI units being operative to generate a fault signal corresponding to a fault condition through an associated main bus or feeder circuit; and a processor in communication with the voltage unbalance detection device and each of the GFCI units for monitoring the voltage unbalance and fault signals, and the processor being capable of generating one or more trip signals corresponding to an actual fault based at least in part on certain predetermined relationships between the voltage unbalance and the fault signals.