# Transformer hookup and voltage drop?



## Darkjim (Aug 7, 2009)

I suggest that you contact Siemens to find out if that Xfmr can be used in reverse applications. Alot of smaller xfmrs are wound with secondary windings inside of the primary windings. When you use them in reverse of what they are intended, they have induction issues. Assuming that you are using a DMM to measure voltage, you are probably picking up ghost voltages at the transformer(because of induction issues)that you do not get further away.

Jim


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## RePhase277 (Feb 5, 2008)

The transformer doesn't know which direction the feed is coming from. I think our problem is that you are trying to get a voltage reading from an ungrounded secondary to ground. In other words, 120 V is being stepped up to 480, but the 480 side has no electrical connection to ground, therefore any reading you take between it and ground is a phantom, because there is no real reference. 

On the supply end, the center tap, H2-H3, of the 480 should be tied to the 120 V circuit ground. You should probably put some fuses in the 480 lines and fuse the 120 V secondary as well. On the receiving end, one leg of the 120 V secondary should tied to ground. Like this:


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## Richard Rowe (May 25, 2009)

Don't mean to be smart about this but did it ever work? I know you said someone else put it in and now your working on it. When you test it at the Boost trans have you put some type load on it or maybe a wiggy to see if the power reading is really there? If you switched the wires and only had a drop on the same wire..... shovel time!


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## Richard Rowe (May 25, 2009)

However don't go a diggin just cause I said so. :laughing:


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## RePhase277 (Feb 5, 2008)

Richard Rowe said:


> Don't mean to be smart about this but did it ever work? I know you said someone else put it in and now your working on it. When you test it at the Boost trans have you put some type load on it or maybe a wiggy to see if the power reading is really there? If you switched the wires and only had a drop on the same wire..... shovel time!


I'm willing to bet he put a digital meter between an ungrounded secondary and ground, and got his strange reading. The conductors between the transformers probably had no connection anywhere to ground, and therefore were "floating", with no real ground reference. The voltages you will read in that case are purely fictional, generated by the capacitance between the wires and whatever you are measuring against.


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## myles (Aug 13, 2009)

InPhase277 said:


> I'm willing to bet he put a digital meter between an ungrounded secondary and ground, and got his strange reading. The conductors between the transformers probably had no connection anywhere to ground, and therefore were "floating", with no real ground reference. The voltages you will read in that case are purely fictional, generated by the capacitance between the wires and whatever you are measuring against.



You would be correct. I wasn't the one who actually did all the testing i had a technician go out there and obviously he knows nothing about electrical. After talking with Siemens today and going out there myself i found out the "actual" problem.


Turns out the transformers were perfectly fine. When i measured the reading between the two hots i had a perfect 480 all the way to the second pull box. After that pull box i was losing about 100 volts on the line. 

The technician was testing it line by line which since he is only used to residential i wont hold too much against him. 

Anyways, turns out the real problem...somehow inside the conduit in the very middle one of the wires split (how...i have NO idea, it looks like maybe there was a nick in the wire and eventually it corroded away the copper?) The entire conduit is full of water and going to be so much fun on Monday morning.


Anyways, i appreciate all the input guys, i just wanted to make sure the transformer was hooked up correctly before we tried doing anymore troubleshooting. Especially since when i was an electrician i was told to NEVER reverse wire a transformer...


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## micromind (Aug 11, 2007)

Deleted, OP found problem.

Rob


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## Richard Rowe (May 25, 2009)

InPhase277 good call you were right on top of that one. I have noticed you are pretty good on trouble shooting posts. I have a habit of overlooking the basic and trying to find complex things that don't exist. Good job.


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## RePhase277 (Feb 5, 2008)

Richard Rowe said:


> InPhase277 good call you were right on top of that one. I have noticed you are pretty good on trouble shooting posts. I have a habit of overlooking the basic and trying to find complex things that don't exist. Good job.


Thanks. I have had my days where I search high and low to figure out why a light doesn't work, and it turns out it was the bulb:laughing: A couple of those and you start looking at the basics first.


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