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30 Degree Phase Shift on Transformers


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#1 robertplant22

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Posted 19 February 2012 - 02:54 AM

Hello,

Can someone verify the statement below for me:

Any step-up or step-down transformer with delta-to-wye or wye-to-delta trasformer will introduce a 30 degree phase shift for positive sequence voltages and currents SUCH THAT THE HIGHER VOLTAGE SIDE LEAD THE CORRESPONDING VALUES ON THE LOWER SIDE.

In most of the information I found on the web; people in forums or documents I found, addressed only step down transformers.

Thanks in advance for your input

#2 mudpuppy

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Posted 19 February 2012 - 02:41 PM

The statement, "SUCH THAT THE HIGHER VOLTAGE SIDE LEAD THE CORRESPONDING VALUES ON THE LOWER SIDE." is not always true. There is a standard that recommends that transformers be connected this way (I don't have access to the IEEE standards from home or I would look for it), but in practice they are not always hooked up that way.

Delta-wye transformers always produce a phase shift, and can be connected for varying phase shifts in increments of 30 degrees, however they are typically connect for either +30 or -30 degrees.

#3 robertplant22

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Posted 19 February 2012 - 10:08 PM

So based on your answer, you will not really know unless the problem indicates what that pahse shift is?

I've run into a couple of these problems; however none of them indicate what the phase shift is. The solutions do seem to be consistent with the statement I posted.

#4 Peele1

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Posted 19 February 2012 - 11:52 PM

Delta Y transformers create a 30 degree phase shift. Camera's EERM and PRM show it fairly well and whether it is positive or negative. One of the many reference books referenced in other subjects has a really good explanation... I don't remember which...




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