Delta system
- Thread starter pgordon
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mayanees
Senior Member
- Location
- Westminster, MD
- Occupation
- Electrical Engineer and Master Electrician
I ran into a problem with this type of system because the UL listed ATS could only sense phase voltages and Onan would not modify the switch for line-to-line voltage sensing because it would compromise the UL listing.
So what seems like a straightforward application where you just use the line voltages from the Y system to power the delta loads, becomes a problem when going through an ATS.
John M
So what seems like a straightforward application where you just use the line voltages from the Y system to power the delta loads, becomes a problem when going through an ATS.
John M
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buddhakii
Senior Member
- Location
- Littleton, CO
Make sure you get an ATS with a switched neutral so you have a SDS. I am working on a project that has a delta service and wye gen. Installing the ATS next month. Hope everything works properly.
kwired
Electron manager
- Location
- NE Nebraska
Is the Delta grounded, or ungrounded? If grounded is it corner grounded or mid point of a phase?
The answers to these questions can change what you may or may not be able to do.
Remember solidly grounded wye needs ground fault protection where the delta would not.
The answers to these questions can change what you may or may not be able to do.
Remember solidly grounded wye needs ground fault protection where the delta would not.
Can you elaborate on your statement? My brain is currently drawing a blank on the concept of NO ground fault protection being permitted.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
I believe that he's thinking of 250.95 but that would only apply when the amperage reached 1000 amps or more.
Hmmm... I can't locate a 250.95 in either 2008 or 2011 NEC. Even if it were there, that is the Part on Bonding???
Perhaps you are thinking of 250.21(B), which requires ground fault detectors on [permitted-to-be] ungrounded systems of greater than 120 volts but not exceeding 1000 volts...
kwired
Electron manager
- Location
- NE Nebraska
It is 230.95. Maybe you just had a typo infinity?
OP has 1200 amp delta. 230.95 requires GF protection @1000+ but only says solidly grounded wye systems.
215.10 also requires same thing for feeders.
But this is not to say there is no ground fault protection [or detection] for delta systems. It simply addresses the fact that on solidly grounded wye systems that gf current on [unprotected] grounded conductor can exceed that of any one ungrounded conductor.
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kwired
Electron manager
- Location
- NE Nebraska
All I was getting at was the fact that he has a delta service that would not require GF protection system, and he is thinking about using a wye generator as a standby. The wye system will require GF protection if solidly grounded neutral. He did not say if the service is ungrounded, corner grounded, or if it has mid point of one phase grounded. We may also need to know what options the generator may have before we know what he can do with it. If the service is corner grounded or ungrounded and the generator is capable of selecting which conductor is grounded it may be relatively simple to match the service with the generator.
I was just giving the OP some food for thought, since we don't know enough about the installation yet to know what he can or can't do.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Yes it was a typo, should have 230.95.
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