3
Wye-Delta Starting
The circuit for wye-delta starting, also called star-delta starting , is shown in Figure 5-27. The three phases of the stator are connected in wye during state-up, and then reconnected in delta when the starting current is sufficiently decreased. All motors connected for wye-delta starting are actually delta-connected machines that are only wye connected for starting purposes. The S contacts provide the wye connection, and the R contacts provide the delta connection. When connected in wye, the voltage across each phase of the stator winding is Vline/ 3.