Nuisance ground fault.
Nuisance ground fault.
(OP)
Dear All,
I have a design paralleling 6 gensets (2180 kW) of 400 V through6 GSU of 3.75 MVA (there will be breakers before the GSU), 0.4/20kV Delta Wye connections.
The Gensets are in wyes and solidly grounded in each gensets (the neutrals will be bonded here). The transformers will solidly grounded too in each of them (the neutrals will be bonded here). They will be feeding 24 kV switchgear and will be supplying load of MCCs in various location. There will be 4 feeders on the switchgear.
Will there be any nuisance tripping on ground fault with this configuration since the shync will on the HV side and the faults will be going back to its source (Transformers)and they all adjacent to each other in the transformer yard.
The question is really if this design is workable(Single line is attached).
Thanks for any feedback.
I have a design paralleling 6 gensets (2180 kW) of 400 V through6 GSU of 3.75 MVA (there will be breakers before the GSU), 0.4/20kV Delta Wye connections.
The Gensets are in wyes and solidly grounded in each gensets (the neutrals will be bonded here). The transformers will solidly grounded too in each of them (the neutrals will be bonded here). They will be feeding 24 kV switchgear and will be supplying load of MCCs in various location. There will be 4 feeders on the switchgear.
Will there be any nuisance tripping on ground fault with this configuration since the shync will on the HV side and the faults will be going back to its source (Transformers)and they all adjacent to each other in the transformer yard.
The question is really if this design is workable(Single line is attached).
Thanks for any feedback.






RE: Nuisance ground fault.
Drawing has switch symbol in breaker location.
Cheers
RE: Nuisance ground fault.
RE: Nuisance ground fault.
All the berakers of 24 kV will be equipped with ground fault protection, any suggestion on the type? since we haven't decide yet.
Thanks.
RE: Nuisance ground fault.
With the currrnt configuration bus differential can also be incorporated using SEL-87E.
Just my own view.
Cheers
RE: Nuisance ground fault.
I would prefer few generators on the common 400kV bus with connection to one or two GSU with bus-tie on the 24kV side.
Synchronization on the 400V breakers.
RE: Nuisance ground fault.
RE: Nuisance ground fault.
You can ask why not 6.6kV or 3.3kV , or 4.4kV
6300A of 400V is very big GCB and lot of copper bars
RE: Nuisance ground fault.
So I'd be using the 24 kV and saving on transformers.
RE: Nuisance ground fault.
sibeen,
You do not want a 20kV generator. Air-cooled machines almost all have PD problems, and I doubt you want the complication of a hydrogen machine.
Run the generators at 3.3kV / 6.6kV and you won't see many problems. PD starts appearing above about 10kV.
RE: Nuisance ground fault.
RE: Nuisance ground fault.
The first intention of using small generators is to have an ease to take each generator from the system once in a time while the need of overhaul is came. Shync all in the 400 V side is resulting in high kA rating, In this design I was wondering weather the grounding system applied could really visibly worked, since I slodly ground all the transformers neutral seperately in each transformer, so i don't have one common bonding of neutral and ground (the same things applied for generators).
any comments?
I make one option for 6.6 kV and get rid the transformers, looks good so far.
Thanks