Answer / mashani

when you see transformer(Medium Viltage Transformer) which
conneted as Y(star) the netral is connected on something
like box....actually its not a box...inside the box is some
inductance which have a value of OHM(it's called NGR"Netral
Grounded Resistance).....
this NGR is used to limited current which will arrived on
netral line.....
it means...when there is fault from phase to ground the
current will be back to the transformer by the netral line
so this NGR is needed installed before this current arrived
to the transformer becoz this fault current is so big and
can destroy the transformer thats why we need NGR

Answer / navin

NGR = NEUTRAL GROUND RESISTANCE

Answer / venkatesh a

NGR- Neutral ground resistor.

Used to limit the ground fault current.
If the Line voltage getting leakage or shorted with ground
then fault curretn will flow.
If it is High voltage system this fault current will be
very high (KAmps). So this much high value fault current
will demage the fault current sensing devices (relays).
This fault current will reach the transformer Neutral
through the Neutral earth pits.
By adding the NGR in between the Transformer neutral and
Neutral earth pit, resistance of the fault current path
getting increase.
we Know that, resistance is more then the (fault) current
flow will be less.
Then easy to sence. Normally resistance will be 12 to 15
ohms depends upon the setting made at relays.

Answer / venkatesh a

For the low voltage systems NGR is not required. If it
necessary then We should consider the relay/Numerical relay
time of fault current allowable, sensing capacity.

In some industries, where the critical areas even though
fault happens they didn't allowing to trip the circuit by
relays.

They maintaining the supply as it is till the next
shutdown.

These resistance are calculated depends upon the fault
current, time delay of fault current, Relay settings.

In my site, we are using the 12.7Ohms NGR for 33/6.6Kv
6.3Mva transformer.

Answer / venkatesh kulkarni

Used to limit the ground fault current.
If the Line voltage getting leakage or shorted with ground
then fault curretn will flow.
If it is High voltage system this fault current will be
very high (KAmps). So this much high value fault current
will demage the fault current sensing devices (relays).
This fault current will reach the transformer Neutral
through the Neutral earth pits.
By adding the NGR in between the Transformer neutral and
Neutral earth pit, resistance of the fault current path
getting increase.
we Know that, If resistance is more then the (fault) current
flow will be less.Then easy to sence. Normally resistance
will be 12 to 15 ohms depends upon the setting made at
relays.

Answer / vishal essar

th e NGR is Neutral gorunding resistor connected to the
Neutral of the star side of the transformer. It si so
connected to limit the fault current getting reflected beoz
of Phase to gnd fault on the Delta side of the Transformer
and also Gnd fault on the same side of the transformer.
Such transformers are for specific loads
like...Motors...specially higher rating motors. The mototr
staring current is very high and a fault at this point can
definnitely destroy the trafo. Hence a NGR is rpovided to
limit the fault current. NGR is a Box having resistor and
Inductors in series parallel connection.

Answer / dhannnuu

NGR 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.

Answer / farhad

A suitably rated power resistor that is connected
between the neutral of a transformer (or generator) and
the system ground. It serves to limit fault currents and
prevent damage to the equipment

Answer / dipak

NGR:- Neutral grounding resister
In high voltage or extra high voltage line NGR is used.
Mainly this NGR are used for to decrease leakege current.
So that current cant able to come to Neutral of the trafo.
so we can save our trafo.
If any big earth fault occur in system that more amount of
current will flow in neatral (Ia+Ib+Ic) so that comes to
Neutaral of the trafo so if we put some resistance than it
disappiate this cuurent in heat purpose not able this
current to trafo.
so that's why NGR rating also have temprature stability and
withstand time.

Answer / md79

Mr. Venkatesh A

Thank you.

What happen if a 18 watt fluorescent tube is used on 36watt choke,which one damaged or not damaged, if damaged why that damaged?

2 Answers   Bharat ITI,

What are the main advantages of generalized error co-efficients?

0 Answers  

what is the reason for balance of voltage in magnetic balance test?

2 Answers   Reliance,

why do harmonics generata?

1 Answers  

if we install two earth pits with a clear space of 5m without any interconnection,by checking the digital multimeter will it show continuity between earth pits? If so what would be the approx. value

0 Answers  

which is the slowest motor? and wt is speed ?

1 Answers  

WE are using a 63A MCCB(SIEMENS MAKE) for one of the feeder in LV substation panel.It is supplying to a lighting & power socket DB.Settings in the MCCB is Ir = 63 * 1 , Isd = 8 times of Ir , tsd = 0.5 sec( I2 t off). Sometimes this MCCB is tripping .But no trip in DB MCB. Can anybody tell me reason ? From where i can know about the MCCB settings?

5 Answers  

what is the basic principle of the alternator ????

2 Answers  

what is the reason for harmonics introduced in the line

2 Answers  

What are the advantages and disadvantages of negative feed back?

0 Answers  

Safety of dry type transformer

0 Answers   Icon,

for high freq ac,why we first convert AC to DC and then DC to high freq.AC

0 Answers