Neutral Grounding Reactors
Neutral Grounding Reactors
(OP)
Resistance/reactance grounding of low voltage generators is new to me.
A number of 400v generators are supplying a stand-alone (island) 400v 4-wire system, a lot of which is single-phase load. Normally the neutral bus would be solidly grounded at one point, but the plant owner has asked for neutral-grounding reactors on each generator. All generators are identical, and circulating current is not a problem, neither is the ground-fault-level.
My question is, could single-phase loads be connected to the system if reactors were added, and if not why not?
A number of 400v generators are supplying a stand-alone (island) 400v 4-wire system, a lot of which is single-phase load. Normally the neutral bus would be solidly grounded at one point, but the plant owner has asked for neutral-grounding reactors on each generator. All generators are identical, and circulating current is not a problem, neither is the ground-fault-level.
My question is, could single-phase loads be connected to the system if reactors were added, and if not why not?






RE: Neutral Grounding Reactors
It is down to local codes whether an impedance-earthed LV system is acceptable - some allow it, some don't. where are you - that would assist in giving an answer.
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RE: Neutral Grounding Reactors
But if you bypass the grounding reactor then you just negated the a major purpose of it. The L-N fault current will not be limited and only true L-G faults will be limited. Probably one of the reasons, I believe single phase loads are not recommended (even prohibited, I need to check on it) to a impedance grounded system in ANSI world.
RE: Neutral Grounding Reactors
RE: Neutral Grounding Reactors
RE: Neutral Grounding Reactors
RE: Neutral Grounding Reactors
Thanks davidbeach.
RE: Neutral Grounding Reactors
250.20(B) requires a solid ground for all systems 50V-1000V that use the "neutral" as a circuit conductor. 250.20(B) would also require a solid ground for any 208V wye system regardless of whether the neutral is used or not.
Once above 1000V you can use low or high impedance grounding, but still can not serve L-N loads due to voltage stability issues on the unfaulted phases during a line to ground fault.