# Transformer Install...



## BBQ (Nov 16, 2010)

I know if you reverse feed a delta - wye that you do not land anything on XO, I don't know if that is the same for a delta delta.


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## oldschoolvdub (Jun 10, 2007)

I have hooked up a few transformers in the past but never used it to step up. In my head I see it as not needing it because it's not like it is using it or needs it for a reference.


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## kevmanTA (Jul 20, 2010)

In the last month, I've seen 1 600-240 hooked up backwards, and 1 240-380V hooked up backwards, Neither had neutrals. 
I also noticed, and correct me if this is way off in left field, the low voltage was on the H lugs of the transformer., it gave us the correct 380V from 240.. I believe it was a Wye.


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## erics37 (May 7, 2009)

I don't see why you would need to land a neutral on it. The neutral point would just float but if you're not utilizing it then it wouldn't matter.


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## oldschoolvdub (Jun 10, 2007)

Now I am getting some kinda weird voltages... High side I'm getting 
A-B= 485
B-C= 486
A-C= 485

Normal right? Well when I turn a 240v 2pole welder on across the shop, i get a small amount of voltage increase on the A-C measurement. It's like 493. Then at one point I measured it and it was almost 500. It seems to be just on the C leg, but I'm not sure if that is ok. I can't really do anything about it if the power in the building is so unbalanced.


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## micromind (Aug 11, 2007)

Don't hook anything to the neutral on the 240 side. Make sure it isn't grounded. 

3 phases in, 3 phases out. 

You'll need to ground the B phase of the 480 side though.

If the neutral one the 240 side is grounded, it'll cause undesirable things to happen. If the 240 building system is not balanced exactly, the grounded neutral on the 240 side of the transformer will carry current. This will cause a slight phase angle shift in whatever winding it's associated with. This will cause a similar phase angle shift on the 480 side, resulting in unbalanced voltage.

From you post, I'd bet the neutral is grounded and I'd also bet it's on the A-C winding. 

Rob.


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