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

how many joint can done in HT line and what is life of the joint

1749


Thermal withstand capability under full short circuit conditions, in terms of number of times of occurrence of short circuit and corresponding anticipated percentage reduction in transformer life.

1968


What is the use of mc( moving coil) in dc voltmeter and dc ammter and what is the use of ( moving iron)in ac voltmeter nd ac ammeter

2361


Why are the cores of large transformers built up of circular transactions ?

1558


Proviiding the Dedicated N earth and individual Body Earths ,Finally these all looped /Now my Question :- will it not harm in case of Transformer Fault current flows in Dediacted N Earthing to Looped Body Earthing.

1743






How many devices can be connected in one zone of FACP

1793


how we sesign the transformer give some specifion regarding design of transformers

1469


draw singleline diagram of star to delta and dol starters

1789


Is there any guideline say about display of earthing value near to earth pit

705


Give some differences between open loop and closed loop?

633


Electronic circuit

606


What are the section criteria for cables. Now everywhere XLPE power cable is used or PVC is also used?.

1232


What Is Sampling?

780


which fault is severe and why?between lll fault and lllg fault which fault is severe and y?

1998


We have a couple of oil tanks at our plant. One of them does not have a lightning arrester installed. My question is it necessary to install an arrestor on every tank or will this particular one be covered by the arrestor installed on the ajdacent tank, Since all the tanks are close to each other. Basically, I want to know that if these arrestors or protection works in a parituclar area of effect or influence. Thanks

1555