hhsting
Senior Member
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- Glen bunie, md, us
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- Junior plan reviewer
Does anyone know of transformer primary is 480V three phase delta to secondary of 240/120V single phase?
Transformer
- Thread starter hhsting
- Start date
- Status
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Why would you need such a transformer? Wouldn't a 1Ø, 480 volt primary work?
zbang
Senior Member
- Location
- Roughly 5346 miles from Earls Court
That's a contradiction, well, I suppose some company might make a transformer with three coils in the primary and a single center-tapped coil for the sec. but that really seems ridiculous. If you want single-phase out, use single-phase in
hhsting
Senior Member
- Location
- Glen bunie, md, us
- Occupation
- Junior plan reviewer
That would work as well. So you are saying 480V single phase to 240/120V single phase? Do you know of such transformers?
zbang
Senior Member
- Location
- Roughly 5346 miles from Earls Court
Should be common as dirt in moderate sizes. How big do you need? (Google turns up a lot of hits- give that a try)
hhsting
Senior Member
- Location
- Glen bunie, md, us
- Occupation
- Junior plan reviewer
45kva
hhsting
Senior Member
- Location
- Glen bunie, md, us
- Occupation
- Junior plan reviewer
With 480V to 240/120V single phase transformer, primary you bring 2 phase and one EGC and secondary you get 2 phase and neutral with EGC out? How does that work typically?
hhsting
Senior Member
- Location
- Glen bunie, md, us
- Occupation
- Junior plan reviewer
Looking at few here
Do 480V to 240/120V transformer have delta or wye windings primary and secondary which?
Do 480V to 240/120V transformer have delta or wye windings primary and secondary which?
Russs57
Senior Member
- Location
- Miami, Florida, USA
- Occupation
- Maintenance Engineer
Can you make do with 208/120V? If so I'd think you are better off going that route with a 3 phase transformer.
Otherwise yes, you can go with 1 phase 480 to 240/120 secondary (Sola ES5H50Sfor example).
Otherwise yes, you can go with 1 phase 480 to 240/120 secondary (Sola ES5H50Sfor example).
- Location
- New Jersey
- Occupation
- Journeyman Electrician
You have a 1Ø primary and a 1Ø secondary, there is no 3Ø wye or delta involved.
hhsting
Senior Member
- Location
- Glen bunie, md, us
- Occupation
- Junior plan reviewer
I am just thinking about grounding such transformer. If one does not know the winding then how does one ground or not NEC 2014 Section 250.30?
zbang
Senior Member
- Location
- Roughly 5346 miles from Earls Court
Delta and wye don't apply to single-phase transformers- see the diagram at https://www.se.com/us/en/product/EE50S3H/xfmr-dry-1ph-50kva-240x480v-120-240v/#mounting-1
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Look at 250.20(B)(1).
hhsting
Senior Member
- Location
- Glen bunie, md, us
- Occupation
- Junior plan reviewer
So only the 240/120V side need to be grounded Not the primary 480V?
hhsting
Senior Member
- Location
- Glen bunie, md, us
- Occupation
- Junior plan reviewer
Ok but secondary terminals I see 2 phases terminal but 240/120V does not have neutral? I dont follow which terminal would have neutral?
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Secondary only. The 480 volt feeding the primary is already grounded somewhere else.
You're creating a neutral by grounding the secondary.
hhsting
Senior Member
- Location
- Glen bunie, md, us
- Occupation
- Junior plan reviewer
I dont follow. On the wiring schematic below link which transformer terminal would be the neutral X2, X3?
EE50S3H - Transformer, dry type, DOE 2016, 50kVA, 1 phase, 240x480V primary, 120/240V secondary, 18H, 150C rise | Schneider Electric USA
Schneider Electric USA. EE50S3H - Transformer, dry type, DOE 2016, 50kVA, 1 phase, 240x480V primary, 120/240V secondary, 18H, 150C rise.
www.se.com
MD Automation
Senior Member
- Location
- Maryland
- Occupation
- Engineer
Yes. Connect X2 and X3, bond it, and that's your neutral. You can see the ground symbol in the chart below on the next to last line.
This puts both secondary windings in series with the X2-X3 connection used as a center tapped neutral. Which gives you...
X1 to X4 = 240V (voltage across both secondary windings)
X1 to neutral = 120V (voltage across one secondary winding)
X4 to neutral = 120V (voltage across the other secondary winding)
The secondary is pretty much just like any normal single phase POCO transformer feeding a residential house.
Last edited:
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
The primary is supplied exactly like any other 2-wire, L-L load: two hots and an EGC, just like you said.
The secondary is exactly like a utility supply: bond the neutral to GEC system, begin EGC system there.
Bond either in the transformer, and wire panel like a sub-panel, or bond in the panel, wire like a service.
The secondary is exactly like a utility supply: bond the neutral to GEC system, begin EGC system there.
Bond either in the transformer, and wire panel like a sub-panel, or bond in the panel, wire like a service.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Straight 240 with no neutral but you can get the idea. The neutral would connect where the SBJ is located.
- Status