Which winding configuration is used during the starting phase in a wye delta starter?

The wye winding configuration is utilized during the starting phase in a wye-delta starter because it significantly reduces the voltage across the motor windings, which in turn limits the starting current. This is particularly advantageous for large motors where a high inrush current can cause electrical stresses and potential damage to the motor and the supply network.

In the wye configuration, each phase winding is connected in such a way that the line-to-neutral voltage is applied to the windings instead of the line-to-line voltage that occurs in the delta configuration. This effectively decreases the starting current to one-third of what it would be with delta configuration while allowing the motor to start more smoothly and overcome initial inertia without the risk of tripping circuit breakers or damaging components.

Once the motor reaches a sufficient speed, the configuration is switched to delta to allow for full operating power, providing the necessary torque and efficiency for normal operation. This sequence of operations illustrates the effectiveness of using wye winding during the initial startup phase.