Grounding of Neutral of Generator: Sizing Issues

Generator is one of the most crucial component of electrical network. This has led to the subject of its grounding receive special attention both from the point of limiting fault current and protection of generator against stator earth fault.

Resistive grounding of generator through Single Phase Transformer is very much in vogue. The type of stressing of grounding equipment, under fault, leading to its own reliability and in turn the generator to be protected needs proper balancing. It is seen that the sizing of Neutral Grounding Transformer (NGT) and associated Neutral Grounding Resistor (NGR) are over safe. This paper discusses the conceptual frame work of sizing considerations and compares it with some of the prevalent practices to drive home the rational of sizing.