30 Degree Phase Shift on Transformers

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robertplant22

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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

 
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.

 
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.

 
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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