TRANSFORMER PHASE ANGLE DISPLACEMENT

[duki]

What causes the phase shift in a delta-wye transformer, is it the way the transformer is connected or the way the transformer is built? Will varing the voltages in each of the windings give a different phase shift? What would a manufacturer have to do to build a transformer with a special phase shift? Thanks in advance.

 

[davidbeach]

There have been many discussions related to this topic in this forum. See also faq238-1287.

 

[waross]

There is no phase shift in the individual windings. It is the way that the windings are connected that causes the 30 degree phase shift.
If you look at the vector sketch for a wye/delta or delta/wye transformer you will see that there is no phase shift between the individual primary and secondary windings.
However, the delta line voltage is the same phase angle as the winding while the wye line voltage is the vector sum of two windings with a 120 degree phase displacement.
The effect of voltage shift in the wye primary of a wye/delta transformer depends on the neutral connection and on the type of core. With a connected neutral, unbalanced primary voltages cause heavy circulating currents.
With a floating primary neutral, unequal primary voltages will cause phase shifts.
A three legged core will act as if it has a phantom delta winding.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[bacon4life]

As Waross indicated, normal transformers are multiples of 30 degrees. For applications such as controlling power flow in a regional grid, more complex transformers can be made such as

http://en.wikipedia.org/wiki/Phase-shifting_transformer.