Clearing Low-Voltage Ground Faults with Solid-State Trips

The danger of undetected ground faults on low-voltage systems is reviewed, and the destruction that arcing faults can cause is explained. The methods of clearing ground faults are discussed, and an economical method of ground-fault tripping is presented. This uses solid-state components to provide a static trip device for low-voltage power circuit breakers which initiates tripping for low magnitude ground faults as well as phase faults and overloads. Coordination curves of a typical system showing selective phase and ground-fault tripping are included.