IEEE Draft Guide for the Application of Neutral Grounding in Electrical Utility Systems, Part IV - Distribution

The neutral grounding of single- a 1 nd three-phase ac electric utility primary distribution systems with nominal voltages in the range of 2.4 kV34.5 kV is addressed. Classes of distribution systems grounding are defined. Basic considerations in distribution system groundingconcerning economics, control of temporary over-voltages, control of ground-fault currents, and ground relayingare addressed. Also considered is the use of grounding transformers, grounding of high-voltage neutral of wye-delta distribution transformers, and interconnection of primary and secondary neutrals of distribution transformers.