Delta-Wye Transformer is a three phase transformer that its primary windings is connected in delta and its secondary windings in star conection.
That conection create a phase shift between primary and secondary voltages of 30° 150° 270° and 330° depending on the conection of delta and star windings.
Also for the case that we have the same number of turns is primary and secondary windings that conection creates a voltage boost in secondary voltage by a factor of √3.
One advantage of that topology is that we are provided with a neutral point in the secondary and thus we can supply single phase loads.
Another advantage is that the delta winding allows third-harmonic currents to circulate within the transformer, and prevents third-harmonic currents from flowing in the supply line.
