Neutral Grounding Resistor

NEUTRAL GROUNDING RESISTOR (NGR) is used for the resistance grounding of Power Systems. Earthing through Resistor is the most common, economical and effective solution for impedance earthing. It is used, when the Neutral of the supply transformer is available and its own impedance is not enough to limit the fault current.

Inserting a Resistor between the Neutral of the Generator/Transformer and Ground serves to limit the maximum Fault Current to a predetermined value. This value is low enough to prevent damaging Fault Currents to the generating, distribution and other associated equipments; yet high enough to operate fault clearing relays.