Answer / db

1.Whats the use of GNAC(Generator Neutral Accessory
Compartment)
Mounting of neutral side CTs and connection to NGR/NGT
2. why generator or any other system require Neutral
Grounding and not Phase grounding
If you ground a phase, you get a soild line to ground fault
3. what happens if any one of the phase is grounded.
An earth fault
4. if 15kv is grounded directly what will happen, why it
should not be grounded like that
Fault current will flow limited only by the impedance in
the circuit
5. use of of NGTR(Neutral Grounding Transformer and
Resistor) for grounding is helpfull and how
They both limit the earth fault current

Answer / mohit kochhar

1. for connecting equipments like ct, pt's.
2. neutral grounding is for flowing of third harmonic
component present in system to ground and it is grounding
at only one side either supply side or recieving side of
one level voltage like 220kv line or 33kv.. mostly on
sending side.
3 earth fault occur.
4 short cicuit current flow. depends on the impedance of
the generator.
5 NGTR is used for lowering fault current which flows
through neutral to the safe value to dissipated to ground
safely.

Answer / jax

1. To keep Neutral side CT (Differential CT, NCT, Measuring
CT, Cross current CT, Isolator switch, etc.

2. Phase can be grounded by isolating neutral. But the main
aim of grounding can not be achived. The potential
difference between ground and other two phase (ungrounded
phase) will raise to line voltage.

3. It depends on the type of grounding. For ungrounded
system no faulr current will flow. But the potential
difference between ground and other two phase (ungrounded
phase) will raise to line voltage. For Solidly grounded
system phase to ground fault current will be high. For Low
resitance grounding, phase to ground fault current will be
quiet less. For High resistance grounding, phase to ground
fault current will be very low. (I can explain more about
this).

4. Simple. Phase to fault current will be more.

5. Using NGTR single phase to fault current can be reduced.
Because of this stress on the conductor due to fault
current can be minimized. But the stress on insulator is
increased because of rise in phase to ground potential
during fault.

For any doubt in Electrical you can contact me at
jaxp333@yahoo.co.in

Answer / shrikant

In case of any one phase failure the neural will not be
generated and hence the equipment supplying power to all
critical equipments will stop in order to avoid this the
neutral is grounded.

Answer / guest

For correct answer please type question and mail it to
raveesh.pintu@gmail.com


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