What is basic fundamental for choosing NGR or NGT for any
generator neutral grounding
Answer Posted / vishal i vadodaria
As we know that in Y connection there are 3 phases [R,Y&B] & a neutral.
In neutral we provide a resistance & than we used to ground it.Such system called neutral ground resistance [NGR].
Why we use NGR?
AS we know ideally the sum of current Ir+Iy+Ib is zero. So in normal condition the current which flow through neutral of Y winding is very low.
In case of occurrence of phase to phase or phase to ground fault heavy unbalance current will be generated & that will flow through neutral. To restrict this current we provide a resistance in neutral.
If we do not provide resistance in neutral & fault occurs at that time a heavy current will flow & it cause excessive heating in stator winding & it may damage the winding. to prevent this we provided a resistance in neutral.
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