The generator stator ground fault dilemma in paper mill systems

The industry has become aware of the problem of severe generator damage due to stator ground faults. Two factors have been identified as contributors to this growing problem-the high magnitude of available ground fault current in complex systems with multiple ground sources, and the persistence of fault current through the faulted-generator neutral after its terminal circuit breaker opens. It has been suggested that to prevent this damage, bus-connected industrial generators should be high-resistance grounded and the number of ground sources on the system should be severely limited. This paper provides a brief review of the problem and examines the implementation of the proposed solutions in typical paper mill applications.