Previous articles (March 3, April 7, and June 2, 2003) covered both the Delta and Wye service transformer’s secondary windings and secondary winding voltages. This article will include primary winding voltages along with the secondary winding voltages. A mathematical formula called the “turns ratio” will also be covered, as well as a mixture of Delta and Wye configurations.
Power is supplied through three-phase circuits containing transformers in which the primary and secondary windings are connected in different Wye and Delta configurations. The four possible configurations are: