how to calculate the ngr capacity(nutral grounding resistor)
Answer Posted / raghavendran.r
As far I know the formula is Rngr = Vln/Ig.
where Ig is the current flowing through the Neutral Grounding resistor(let through fault current), which depends upon the type of system you haver chosen, i.e High impedance grounding or Low resistance earthing.
The let through ground fault current through the neutral is low for High resistance earthing and its High for low resistance earthing.
But the important condition is that the let through fault current should be greater than the system capacitive charging current to avoid transient over voltage.
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