Can a wye generator run a delta system?
- Thread starter roberius
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- Lockport, IL
- Occupation
- Retired Electrical Engineer
I see no reason why it could not. You just don't run or connect a neutral wire. All the load sees is a set of three wires being brought to it. The load cannot discern how those wires are connected to each other at the generation end.
mbrooke
Batteries Included
- Location
- United States
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- Technician
It wont matter.
- Location
- Placerville, CA, USA
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- Retired PV System Designer
What he said. A 480Y/277 will be 480V line to line. A 480 Delta will also be 480 line to line.
Now if your delta distribution system is corner grounded or ungrounded with an unrepaired ground fault you will have serious problems.
Now if your delta distribution system is corner grounded or ungrounded with an unrepaired ground fault you will have serious problems.
That would have been helpful information at the outset.
- Occupation
- Licensed Electrician
It still shouldn't matter unless somebody tried to connect the neutral from the generator to the delta system.
They connected the neutral from the generator to ground.
zbang
Senior Member
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- Roughly 5346 miles from Earls Court
That would do it (and short the generator's B phase).
Basically, somebody really messed up the generator connections, but that could happen with any grounded source connecting to a differently grounded system (problem wasn't the generator, it was the person connecting it).
- Location
- Placerville, CA, USA
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- Retired PV System Designer
Or the generator wiring included SPDs to ground from the line terminals.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
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- Electrical Contractor
Definitely the problem. The generator output (in its entirety) should be grounded at only one point, as with any supply, and in this case, determined by the grounded phase.
You grounded one point (the neutral) from the generator and a different point (B phase) at the load, which created a direct B-to-N short and is why you overloaded the CTs.
ggunn
PE (Electrical), NABCEP certified
- Location
- Austin, TX, USA
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- Consulting Electrical Engineer - Photovoltaic Systems
Oops.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
And if done properly should only be bonded at the service disconnecting means, amd run separate EGC's beyond that. This is exactly what you would do with wye supply anyway.
If you have three pole breakers (switching grounded conductor on each circuit simultaneously with ungrounded conductors) you can do the wye thing fairly easily as long as there are no B to ground bonds and you have separate grounding bus at the main gear. If you have two pole breakers or fuses connecting the wye generator gets more involved
oldsparky52
Senior Member
- Location
- Wilmington, NC USA
Are you allowed to let the neutral float in the generator? If so, wouldn't this work just fine?
I guess you would have to have a ground detector of some sort?
I guess you would have to have a ground detector of some sort?
kwired
Electron manager
- Location
- NE Nebraska
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- EC
to a certain extent I don't see why one couldn't leave it float and ground a phase. If you bring the neutral out in any way then it must be the grounded conductor.
When it comes to NEC requiring the neutral to be the grounded conductor - it applies when you actually have a neutral to ground. Simple 120/240 single phase secondary configured to be used for 240 only (maybe to supply European equipment?)- ground one end and do not use the center tap for anything - really not any different.
oldsparky52
Senior Member
- Location
- Wilmington, NC USA
.
Since the service the generator is feeding has a grounded "B" phase, would you need to ground a phase at the transformer?
If you did, it would have to be "B" phase of course.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Where you ground depends if your transfer arrangement is set up as separately derived system or not. For non separately derived, you already have bonding at the service equipment, your "grounded conductor" should not have any fuses in it and should not have any switches or circuit breakers unless they also simultaneously open all conductors of the circuit - and you should have a separate EGC run from transfer equipment to generator frame, but no bonding to the "B" phase, that would introduce parallel paths for the grounded circuit conductor.
Last edited:
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
190611-0751 EDT
Whether something is a wye or delta has to do with wiring or configuration of the device.
Wye or delta alone says nothing about grounding. If you want to define how it is grounded, then you must add some qualifier to indicate means of grounding, if there is any grounding.
In many large industrial plants floating deltas are used. Where the lines (wiring) float relative to ground (earth) is determined by distributed capacitance and leakage of the distribution wiring and loads.
The words alone of wye or delta do not require or imply any grounding. Many, possibly most, electricians make some assumption of a particular way of grounding for a wye or delta. This can be a major mistake as indicated by this thread.
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Whether something is a wye or delta has to do with wiring or configuration of the device.
Wye or delta alone says nothing about grounding. If you want to define how it is grounded, then you must add some qualifier to indicate means of grounding, if there is any grounding.
In many large industrial plants floating deltas are used. Where the lines (wiring) float relative to ground (earth) is determined by distributed capacitance and leakage of the distribution wiring and loads.
The words alone of wye or delta do not require or imply any grounding. Many, possibly most, electricians make some assumption of a particular way of grounding for a wye or delta. This can be a major mistake as indicated by this thread.
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kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Correct. Where some get confused is NEC requires the neutral to be the point that is grounded. If you are not utilizing the neutral for any loads you don't necessarily have a neutral and can leave it as an internal point in the source and only bring out the three other leads for utilization, in that case to have a grounded system you must ground one of those three leads.
We do this all the time with delta systems made up of a bank of single phase transformers. Each one has a mid point, but we build a corner ground system by not tying into any of those mid point taps. Tie into one of them with a conductor for utilization purposes and it must become the grounded conductor per NEC and you end up with a high leg system.
Can a Three-phase 480VAC generator be connected as a wye source to a delta-connected load?
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