208/120 VAC vs. 120/208 VAC

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jim dungar

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GoldDigger

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It is single phase, there is only one L-L voltage, therefore it is 120/208 or 277/480.

Here is one utility that agrees with me.
WPS service manual
http://www.wisconsinpublicservice.com/business/manual/1_4.pdf
OK. There is only one line-to-line voltage, but it is not in phase with the line to neutral voltage. That is what I have problems with.
It is either one third of a delta, which is one phase, or it is two thirds of a wye, with two phasors.
 

GoldDigger

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Here is one utility that agrees with me.
WPS service manual
http://www.wisconsinpublicservice.com/business/manual/1_4.pdf

I like to think it is because there is only one L-L voltage.

The only problem I have with that as a reference is that WPSC lists all of the options as 120/240 single phase, 120/208 single phase, and 120/208 three phase.
Result is like the two old ladies on the plane to Hawaii who wanted to know how to pronounce the name of the island.
 

templdl

Senior Member
Location
Wisconsin
OK. There is only one line-to-line voltage, but it is not in phase with the line to neutral voltage. That is what I have problems with.
It is either one third of a delta, which is one phase, or it is two thirds of a wye, with two phasors.

It may play with your mind a bit but it is still single phase. When ever you take power from X1 and X2, or X2 and X3, or X3 toX1 there are all phase to phase single phase voltages. The voltage is derived from a single winding of a wye connected transformer, A-B, B-C, and C-A.
 

GoldDigger

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It may play with your mind a bit but it is still single phase. When ever you take power from X1 and X2, or X2 and X3, or X3 toX1 there are all phase to phase single phase voltages. The voltage is derived from a single winding of a wye connected transformer, A-B, B-C, and C-A.

Yes, but you have two different single phases! I know that it is not two phase, that would be 90 degree quadrature.
 

GoldDigger

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It may play with your mind a bit but it is still single phase. When ever you take power from X1 and X2, or X2 and X3, or X3 toX1 there are all phase to phase single phase voltages. The voltage is derived from a single winding of a wye connected transformer, A-B, B-C, and C-A.

Oh, and a line to line load on a wye connected transformer is in fact coming from two windings, not just one!!!!

It would be one winding if we were looking at a delta.
 

jim dungar

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Location
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Retired Electrical Engineer - Power Systems
Oh, and a line to line load on a wye connected transformer is in fact coming from two windings, not just one!!!!

It would be one winding if we were looking at a delta.

You will notice that the word "phase" is one of the most ambiguous words we use in our industry.


Stop considering the neutral at all.
Now what is the difference between the L-L voltages of a single winding, two windings in series or two windings 120? apart?
 

Smart $

Esteemed Member
Location
Ohio
Yes, but you have two different single phases! I know that it is not two phase, that would be 90 degree quadrature.
Think of it this way... it is single phase because the only typical loads you can connect to it are single phase. You can't connect a typical (balanced) 3? load to it without setting up a transformer to derive the third phase.
 
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