Neutral Grounding Contactor in Diesel Generator

there wont be any current flow in neutral if DG is loaded equally in 3 phases , if there any fault(earth fault or over load) in any one of the phase ,then there will be un balanced load in DG . at that time heavy current flow through the neutral ,it is sensed by CT and trips the DG. so neutral in grounded to give low resistance path to fault current

but why a special neutral grounding contactor is used in diesel generator?

your system is >600V and few genset is syn in the sysem?

I dont think any special contactor is needed. the contactor is just control only 1 point of grounding only.

hi friends

there is use of neutral earthing resistor system used in different DG at synchronize if there is three generator set are synchronize and load shared then how much NGR system panels required.

Regards.

sajid

You need a neutral to make any incidental electrical instrumentation work, panel lights for example

Depending the connection of the windings in the generator and the load. Always in 3 phases star system you will need a neutral center point to absorb the differences on the load of each phase, moreover depending what configuration 3 phases or 1 phase for instance you will need a ground connection. Again and equal to a doctor answer, I need to see the generator to be more specific.

Neutral grounding contactor required only when you are useing more than one

generator to run parrall opration .

For exmple you have two generator A and B,

when you stating A generator first,you have to close the neutral contector of

the A generator only ,then you have to syncronice the B generator .

1) I think this posting is about Neutral contactor.

This is only use in MV or HT, LV dont need.

2) About Neutral grounding Resistor is diff.

this is to control the earth fault current. R = V(1 phace) / I

An electrical system consisting of more than two low voltage Diesel Generator sets intended for parallel operation shall meet the following conditions:

(i) neutral of only one generator needs to be earthed to avoid the flow of zero sequence current.

(ii) during independent operation, neutrals of both generators are required in low voltage switchboard to obtain three phase, 4 wire system including phase to neutral voltage.

(iii) required to achieve restricted earth fault protection (REF) for both the generators whilst in operation.

Solution:

Considering the requirement of earthing neutral of only one generator, a contactor of suitable rating shall be provided in neutral to earth circuit of each generator. This contactor can be termed as "neutral contactor".

Neutral contactors shall be interlocked in such a way that only one contactor shall remain closed during parallel operation of generators. During independent operation of any generator its neutral contactor shall be closed.

Operation of neutral contactors shall be preferably made automatic using breaker auxiliary contacts.

You can find your answer about diesel generators at GoPower.com. They should have an answer for you Seaboy.