National Resistors

Other Details

Neutral Grounding Resistor is used 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 Resistor should be so chosen that the fault current is limited to that necessary to operate the protection relays within the required time. For Grounding Neutral of Transformer or Generator, Resistors up to 66 KV are offered for fault of short duration like 10 sec., 30 sec., 60 sec., continuous etc. Material of resistor is normally Stainless Steel, FeCrAl, Cast Iron, Copper Nickel or Nichrome. Temperature rise is normally 375o C/760oC or as required by customer.