Ground fault protection for electric utility generating station 480-volt auxiliary power systems

Many generating station 480-volt auxiliary power systems employ a WYE distribution system with the source neutral solidly grounded. Because of the arcing nature of some ground faults, the ground fault currents developed on these systems are often too low to operate phase overcurrent protective devices. As WYE systems became more popular, a more sophisticated approach to protection was needed, resulting in the development of many new protective devices for ground fault protection. This paper reviews the application of such ground fault protective devices for use in 480-volt auxiliary power systems of generating stations. In addition, some modifications to existing products are suggested.