only some transformers and some generator requires NGR why?

Answer Posted / pavan

NGR - Neutral Grounding Resistor is used to limit the fault
current of a sytem.

So generally a system with high line voltage of 3.3KV and
above normally comprises of high load equipment which
results in very high fault currents due to a Short-circuit
fault. Normally during a Earth fault the fault current
flowing through the earthed phase is to be carried by the
remaining phases which may be very much more than the
rating of the conductors. So we follow the Neutral
Grounding practice so that the fault current is carried by
the nuetral.

Now this current carried by the nuetral is to be limited
such that this high fault current does not damage the
grounded equipment so in the neutral we insert a resistance
which is the NGR.

So for any high voltage system to limit the fault current
NGRs are used. for the equipment working at lesser voltage
normally can withstand the short circuit currents for short
time.

Is This Answer Correct ?    10 Yes 0 No



Post New Answer       View All Answers


Please Help Members By Posting Answers For Below Questions

we have 3 single phase transformers. how will we generate 6 supply from 3 phase supply input

1660


how to control the speed to switched reluctance motor

1497


i have attended the interview on 4th June,08 at Kolkata in IOCL, can anybody tell me what is its result

1553


when will be the iocl interview results ifaced the interview on september 8 th

1639


what is difference between earthingpits,earthing grid & earthing mess?

2062






What should be the amps for a MV fuses for transformer 630kVA 20(10)/0.4 kV

1602


can we use CBCT in neutral of solidly grounded transformer? in place of three phases we can pass only one phase which decreases the size of CBCT?

1777


Is it required to lay GI wires along with GI/MS conduits from one point to another point though separate earthing cable is conncted from DB to Socket?

1539


what is the difference between unarmoured & Flexible cable? How to identified?

5441


How I can Compare 120v/60Hz versus 220v/50Hz ? Please tell me both advantage and disadvantage ......

1565


What is the difference between isolators and electrical circuit breakers?

631


What will happend if given Vfd out put to step up transformer

1249


Greeting to all members, How to calculate spill current when we have different ratio CT and Class for REF(Low Imp) I have 500/1A 5P20 @line side n 400/1A CL.X @ Neutral.

2548


300m long and 30kw inductive loade 3phase supply how many size cable required

1002


why 1.7Uo for HV cable Hi pot test?IE standard why?

1878