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#69960 - 09/26/06 11:12 AM back up generators
jersey Offline
Member
Registered: 02/19/05
Posts: 13
Loc: Hopatcong N.J. 07843
I am installing a 35 kw generator to backup a 70 amp 3 phase sub panel. My question is if the building has a delta high leg service, will this effect the generator?
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#69961 - 09/26/06 11:34 AM Re: back up generators
LarryC Offline
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Registered: 07/05/04
Posts: 780
Loc: Winchester, NH, US
ASSume voltage is 120/240 center tapped delta.

What are the loads on the sub panel? All single phase, all 3 phase, or mixed? If mixed, can the generator supply them, or are you going to use a transformer? Remember the issues with SDS and grounding through transfer switches.
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#69962 - 09/26/06 12:27 PM Re: back up generators
jersey Offline
Member
Registered: 02/19/05
Posts: 13
Loc: Hopatcong N.J. 07843
With the 3-3 phase refridgerator units and single phase 240v water pump each leg was drawing around 31 amps apiece. Thera are other small loads.
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#69963 - 09/26/06 12:34 PM Re: back up generators
resqcapt19 Offline
Member
Registered: 11/10/00
Posts: 2148
Loc: IL
Can you get a generator that will supply 120/240 3 phase 4 wire?
Don
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#69964 - 09/29/06 07:06 AM Re: back up generators
jersey Offline
Member
Registered: 02/19/05
Posts: 13
Loc: Hopatcong N.J. 07843
the guardian type. They make 3 phase generators
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#69965 - 09/29/06 07:33 AM Re: back up generators
resqcapt19 Offline
Member
Registered: 11/10/00
Posts: 2148
Loc: IL
jersy,
Quote:
the guardian type. They make 3 phase generators

They are all 3 phase wye connected units. That is not the same as a 3 phase delta system with a high leg. I have never seen a generator that could be connected 3 phase delta with a high leg. I have only seen that configeration on transformers.
Don
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#69966 - 09/29/06 10:40 AM Re: back up generators
LarryC Offline
Member
Registered: 07/05/04
Posts: 780
Loc: Winchester, NH, US
When I repaired generators many years ago, the small gennys on reefer trucks were 3 phase 240 delta. I don't know if they where available in anything larger than 5 or 10 KW.

If the Guardian you are talking about has a 12 lead alternator, you could rewire it for 120/240 delta with a high leg. I would check with the factory about the maximum unbalanced load.

Larry
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#69967 - 09/30/06 07:11 AM Re: back up generators
resqcapt19 Offline
Member
Registered: 11/10/00
Posts: 2148
Loc: IL
Larry,
Quote:
If the Guardian you are talking about has a 12 lead alternator, you could rewire it for 120/240 delta with a high leg.

I didn't look at all of the wiring diagrams, but on the ones that I did look at, the center of the wye was an internal connection.
Don
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Don(resqcapt19)
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#69968 - 10/05/06 07:52 AM Re: back up generators
jersey Offline
Member
Registered: 02/19/05
Posts: 13
Loc: Hopatcong N.J. 07843
Just talked to guardian . There 3 phase units not compatible with a delta system. I have a meat packing plant that needs emergency back-up . Power always goes out they dont want there meat to go bad. Is ther an other way to go?
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#69969 - 10/05/06 08:04 AM Re: back up generators
jersey Offline
Member
Registered: 02/19/05
Posts: 13
Loc: Hopatcong N.J. 07843
one more question , Why would it matter if the back-up generator Was a wye ? The equipment would work 3 phase, delta or wye connected
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