Answer Posted / soumen
NGR (Neutral Grounding Resistors )is employed in AC
distribution networks to limit the fault current which
would flow from the transformer or generator neutral star
point in the event of an earth fault in the systems. It is
used when the neutral of supply transformer is accessible
and its own impedance is not enough to limit fault current.
The rating of the protection relays within the required
time.
For Grounding Neutral of Transformer or Generator,
Resistors upto 33 KV are offered for fault of short
duration like 10 sec., 30 sec., 60 sec., continuous etc.
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