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back up generators #69960
09/26/06 02:12 PM
09/26/06 02:12 PM
J
jersey  Offline OP
Member
Joined: Feb 2005
Posts: 13
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?

Work Gear for Electricians and the Trades
Re: back up generators #69961
09/26/06 02:34 PM
09/26/06 02:34 PM
L
LarryC  Offline
Member
Joined: Jul 2004
Posts: 783
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.

Re: back up generators #69962
09/26/06 03:27 PM
09/26/06 03:27 PM
J
jersey  Offline OP
Member
Joined: Feb 2005
Posts: 13
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.

Re: back up generators #69963
09/26/06 03:34 PM
09/26/06 03:34 PM
R
resqcapt19  Offline
Member
Joined: Nov 2000
Posts: 2,148
IL
Can you get a generator that will supply 120/240 3 phase 4 wire?
Don


Don(resqcapt19)
Re: back up generators #69964
09/29/06 10:06 AM
09/29/06 10:06 AM
J
jersey  Offline OP
Member
Joined: Feb 2005
Posts: 13
Hopatcong N.J. 07843
the guardian type. They make 3 phase generators

Re: back up generators #69965
09/29/06 10:33 AM
09/29/06 10:33 AM
R
resqcapt19  Offline
Member
Joined: Nov 2000
Posts: 2,148
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


Don(resqcapt19)
Re: back up generators #69966
09/29/06 01:40 PM
09/29/06 01:40 PM
L
LarryC  Offline
Member
Joined: Jul 2004
Posts: 783
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

Re: back up generators #69967
09/30/06 10:11 AM
09/30/06 10:11 AM
R
resqcapt19  Offline
Member
Joined: Nov 2000
Posts: 2,148
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


Don(resqcapt19)
Re: back up generators #69968
10/05/06 10:52 AM
10/05/06 10:52 AM
J
jersey  Offline OP
Member
Joined: Feb 2005
Posts: 13
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?

Re: back up generators #69969
10/05/06 11:04 AM
10/05/06 11:04 AM
J
jersey  Offline OP
Member
Joined: Feb 2005
Posts: 13
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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