Transformer

[hhsting]

Does anyone know of transformer primary is 480V three phase delta to secondary of 240/120V single phase?

 

[infinity]

Why would you need such a transformer? Wouldn't a 1Ø, 480 volt primary work?

 

[zbang]

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]

Why would you need such a transformer? Wouldn't a 1Ø, 480 volt primary work?

That would work as well. So you are saying 480V single phase to 240/120V single phase? Do you know of such transformers?

 

[zbang]

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]

Should be common as dirt in moderate sizes. How big do you need? (Google turns up a lot of hits- give that a try)

45kva

 

[hhsting]

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]

Looking at few here

https://images.tradeservice.com/9ETBOIYK8205G6UU/ATTACHMENTS/DIR100248/SCHNDRE07424_14_2_14_3_14_7.pdf

Do 480V to 240/120V transformer have delta or wye windings primary and secondary which?

 

[Russs57]

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).

 

[infinity]

Do 480V to 240/120V transformer have delta or wye windings primary and secondary which?

You have a 1Ø primary and a 1Ø secondary, there is no 3Ø wye or delta involved.

 

[hhsting]

You have a 1Ø primary and a 1Ø secondary, there is no 3Ø wye or delta involved.

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]

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

 

[infinity]

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?

Look at 250.20(B)(1).

 

[hhsting]

Look at 250.20(B)(1).

So only the 240/120V side need to be grounded Not the primary 480V?

 

[hhsting]

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

Ok but secondary terminals I see 2 phases terminal but 240/120V does not have neutral? I dont follow which terminal would have neutral?

 

[infinity]

So only the 240/120V side need to be grounded Not the primary 480V?

Secondary only. The 480 volt feeding the primary is already grounded somewhere else.

Ok but secondary conductor I see 2 phases 240/120V does not have neutral? I dont follow which terminal would have neutral?

You're creating a neutral by grounding the secondary.

 

[hhsting]

Secondary only. The 480 volt feeding the primary is already grounded somewhere else.

You're creating a neutral by grounding the secondary.

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]

I dont follow. On the wiring schematic below link which transformer terminal would be the neutral X2, X3?

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.

 

[LarryFine]

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.

 

[infinity]

Straight 240 with no neutral but you can get the idea. The neutral would connect where the SBJ is located.