High-Resistance Grounded power system equivalent circuit damage at the line-ground fault location (Part 2)

This paper provides electrical equivalent circuits of High-Resistance Grounded (HRG) power systems other than a delta-wye connected utility power supply transformer included in Part 1 of this paper. This paper provides HRG grounding of a medium voltage (MV) generator for connection to an industrial power system and to a utility power system, and discusses line-ground fault with fault resistance. Three-line diagrams of ungrounded power systems to illustrate the HRG grounding application and its effect on ground fault current during line-ground fault are also included. The damage at the fault location is based upon the assumption that the fault remains a line-ground fault until it is cleared by appropriate ground fault protection relays. Fault resistance and fault current that has an effect on damage at the fault location is included. This paper provides guidance to update the current edition of IEEE STD. 142 with respect to HRG systems.