4-wire ats on 3-wire system

[RUWired]

Can a 4-wire A.T.S. with a solid neutral,be used on a 3-wire system with out any metering currents showing up on the ground wire?

The neutral from the utility is bonded in the main ocpd and goes no further. The neutral is bonded in the gen set ocpd's ( 2 ea.) and goes no further.Ground wires interconnect every thing all the way into the building.

Might also ask, does the ground fault protection in the main gear work off the current on the ground wire or the difference between the the current on the neutral and the ground wire?

 

[iwire]

Can a 4-wire A.T.S. with a solid neutral,be used on a 3-wire system with out any metering currents showing up on the ground wire?

The lack of current on that solid pole will not be an issue.

The lack of potential between the other poles to the unused pole may be an issue. The ATS may see that as a power failure and try to transfer.

This problem may be solved by re-programing the switch, changing some settings or just bringing the neutrals from the utility and generator to the switch but no further.

Might also ask, does the ground fault protection in the main gear work off the current on the ground wire or the difference between the the current on the neutral and the ground wire?

The service GFP works on the current imbalance on all the circuit conductors.

 

[bbaumer]

What would the intended application be for a 4 pole transfer switch with solid neutral, i.e. a 5 wire system. That would be a strange bird I would think. Maybe not though, just never run into one of those. Never seen a 5 wire generator either.

The ground fault sensor on main gear typically amounts to a large CT around all the phases and the neutral. The thinking is here all currents cancel each other out. If they do not that means the earth is a path for unbalanced current back to the transformer. GFI on switchgear is not the same as on a branch breaker or GFCI receptacle. The trip threshold is usually in the hundreds of amps not milliamps. The function is to protect the gear, not people.

 

[iwire]

What would the intended application be for a 4 pole transfer switch with solid neutral,

The solid neutral is a pole.

So you have A, B, C, N.

 

[bbaumer]

The solid neutral is a pole.

So you have A, B, C, N.

Duh. I was misreading his post thinking there were 4 switched poles PLUS a solid neutral.

I've always heard that referred to as a 3 pole transfer switch with solid neutral. The OP did say 4 wire, not 4 pole, hence my mistake.

 

[mdshunk]

What's the brand and model of the ATS? There is at least one I know of that can be configured to ignore a dead leg. Having power missing on one fo the legs will make most ATS's transfer, and that wouldn't exactly work out for you.

I guess this is something your tore out someplace and want to use at home?

 

[RUWired]

What's the brand and model of the ATS?

This is an ASCO 3200 amp closed transistion with bypass 480/277 volt.It has the 7000 series brain.I'll check with the start up tech before hand and see if it's going to be an issue.
Rick

 

[mdshunk]

This is an ASCO 3200 amp closed transistion with bypass 480/277 volt.It has the 7000 series brain.I'll check with the start up tech before hand and see if it's going to be an issue.
Rick

ooooooooooh. I've put that model in before, but don't know much about it. I'm more familiar with the 300. They certainly make it in single phase, if you want it that way. I feel I can say with certainty that it will transfer if you have an empty lug on the normal side for one of the legs. There might be a way around it with the programming. Yikes. Best of luck with that one.

 

[iwire]

I bet that can be programed to ignore the neutral.

 

[mdshunk]

I bet that can be programed to ignore the neutral.

:smile: It just now dawned on me that he's talking about 3-wire, as in delta. I was reading 3-wire, and thinking single phase (2 legs and a neutral). Disregard everything I said.

 

[chris kennedy]

I bet that can be programed to ignore the neutral.

I don't know about Ricks model but I have installed 4 pole wye ATS's that ignore the grounded conductor. If you lose the POCO neutral the ATS will sense wacky voltages on the ungrounded conductors and transfer.

 

[RUWired]

I actually have a 480/277 "Y" set up with the utility and the gen set.All the loads are motor control centers off the ats.The main from the utility has the ground fault protection in it.Engineer did'nt call for any neutrals.