PROJECT TITLE :

Grounding of Primary System for LV Networks

ABSTRACT:

Secondary or low-voltage (LV) networks are applied in many massive cities throughout the U.S., and in some other countries. Numerous grounding schemes have been employed for the primary systems supplying these secondary networks. In this paper, characteristics of the different grounding schemes for the substation and primary feeders that offer the LV networks are reviewed. The impacts of primary system grounding on the ground fault currents, the unfaulted line-to-ground voltages, further because the voltage sags in the LV network are considered for the one line-to-ground fault on the primary. The variations between systems with network transformers having the delta- or grounded-wye-connected primary windings are discussed. The relationships between grounding characteristics and protection settings, as well as actual examples, have been documented.