Phasor and directions of a bolted single-phase-ground fault current in a high-resistance grounded (HRG) power system

This paper reviews the phasor and directions of a single-phase-ground fault current (s) in a high-resistance grounded (HRG) power system. A brief review of the published literature, which is inconsistent, has caused confusion on what should be the correct phasor and fault current directions to be used in dot standard P3003.1. An application concept that during single-phase-ground fault condition, “distributed capacitive current direction reverses in the two un-faulted phases” compared to the direction under normal system operation. This concept has been applied before [2] [6]; however, some application engineers raised the question on this concept. The concept is currently used in the modern ground fault protection relays used for HRG and ungrounded power systems. It has no impact on the operation of the power system during the phase-ground fault condition, but it helps in providing ground-fault current flow from faulted location to ground, a normal industry convention. The paper will provide guidance on how to update the contents of the HRG system contained in the current edition of IEEE STD. 142 to be used for Dot Standard P3003.1 [23].