I have an Acme industrial control transformer that I need help wiring. On the top part of the transformer there a 4 terminals. From left to right they are:

H1 - X - H3 - X

And on the bottom, they are:

X3 - F - X - X1

It is 277v in and 120v out.

What is the proper way to wire this? Where do I get my neutral and ground? I would appreciate any help. Thanks.

 

Welcome to the forums!

It should be 277 to H1 and H3, 120 to X3 and X1, and neutral from X. Ground is fed through and bonded to the case; it is nod derived from the xfmr.

 

Thank you and I have three more questions, to get 277 to both H1 & H3 can I bring one leg to the transformer and jumper it over or does it have to be two individual feeds? I have 3 phase in the panel so it is not a problem to have 2 feeds. Also, do I pull the nuetral for the 120v circuit from the X on the bottom of the transformer? Last, do I feed a neutral one of the X's on the top of the transformer from my 480 panel that I am feeding the 277v leads from? Thanks again.

 

277 is like a higher voltage version of 120v.... meaning you get 277v from neutral to hot leg. Between 277v legs is 480v. A little confusing. So if you brought over two hot legs you would be connecting 480v to the transformer


So therefore in your case you will have a neutral and a hot leg connected to the H terminals. I don't like telling people how to wire a transformer without being there. Can you get a part number for this Acme transformer. There may also be a jumper issue. I'm looking at the Acme wiring diagrams and the terminal letters you posted don't match the ones in their diagrams. Closest diagram is 7.

http://www.acmepowerdist.com/pdf/Page_147-156.pdf

 

Here is a picture of the transformer. It is an Acme like I mentioned but I cannot find this particular model number on there website, that is why I came here. Thanks again.

 

Yes, exactly.

No, two hot legs.

That makes two of us. This one does seem pretty straightforward, though.

 

Two individual 277V feeds.

Probably, but the surest way is to test for 120V from X1 and X3 to the various Xs after you power up.

IDK. Can't remember feeding neutral on the primary side to any xfmer.

 

Be careful on this one. How can you bring over two individual 277v feeds ? You get a 277v circuit from hot to neutral. If you did bring over 2 feeds they would have to be on the same phase and that would yield nothing. If they were on different phases it would be 480v.


Let me check on this transformer. If you don't get a response be sure to bump it up on Sunday.

Is it possible to get just a picture of the label ? Thanks.

 

Right. And if they're not on different phases you won't get 240/120 out.

But if what you're saying is that it's tricky to get 240/120 out of 480Y/277, you're right. It's damn near impossible. Much easier to get 208Y/120. That may what comes out. I'd feel more confident if the pictures showed open windings with multiple taps. Or, better yet, movable taps.

The good news is that most devices that "require" 240V really require 220V, so that both 240 and 208 are within their tolerance.

We'll see. The OP already owns this xfmer. Worst case, he'll have to replace it.