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Joined: Jul 2004
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That could just be open delta wired wye primary. Actually pretty normal here using 2 transformers. One of the transformers is center tapped on the secondary and off you go. I can get a picture of that at the "shop and rob" at the end of my street.
Greg Fretwell
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That could just be open delta wired wye primary. Actually pretty normal here using 2 transformers. One of the transformers is center tapped on the secondary and off you go.
Yah, I've seen that 2 transformer connection very often. But those transformers are usually connected to a 4 wire wye system with a grounded neutral. I found a picture of a transformer like I was asking about: http://www.electricalphotos.com/showphoto.php/photo/425/ppuser/28This picture is very similar to the one I seen in that other book. Could it be a three phase unit or not?
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Joined: Apr 2004
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I don't think I've ever seen a US pole mounted three phase transformer before in real life. (Post those pics guys ) Okay, I happened to catch one in the background of a pic I took today (yes of traffic lights). Closeup of single transformer: Ian A.
Is there anyone on board who knows how to fly a plane?
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Re: 3 phase rectangular pole mounted transformers.. Ya usually the PoCo will use 3 separate cans for a 3 phase service drop to a large building but it is NOT uncommon to see a single 3phase transformer of 150 KVA or less on a pole. Usually I have seen them where a building is an older one and had a separate 3 phase service strictly for an elevator or other motor driven equipment.
Don't worry fellas, I am working on those pix still. I know where there is a nice brand-new installation of one of these transformers, right outside my friends 7'th floor balcony.. I will have them in the next few days!
A.D
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I have never seen 2 transformers wired wye secondary. It is usually red leg delta around here.
Greg Fretwell
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Yah, I've seen that 2 transformer connection very often. But those transformers are usually connected to a 4 wire wye system with a grounded neutral. I have never seen 2 transformers wired wye secondary. It is usually red leg delta around here. Sorry I should have been more clear. I meant to say the Primary is wye connected.(each transformer is connected phase to neutral). Yes the secondary is open delta with a high leg.
Last edited by junkcollector; 04/16/08 07:12 PM.
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10-4 That sounds regular here. I will try to remember my camera tomorrow.
Greg Fretwell
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This is the label on a 50KVA like the one at the top of this thread.
Greg Fretwell
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The 50 KVA up close
Greg Fretwell
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Here is an American open delta setup with a 3-wire (no MGN) primary. Grounding is done by local rod at the pole. This particular setup is in the high desert area in Sothern California Edison territory where I noticed that most, if not all of the local distribution, was done with no MGN and the transformers connected L-L. This would be considered unusual by US standards which is mostly MGN distribution.
Peter
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