What is a Star-Delta Starter and How Does It Work?

What is a Star-Delta Starter and How Does It Work?

The star-delta starter is one of the most commonly used starters for three-phase induction motors. It is popular because it is an efficient and relatively simple method for reducing the starting current of a motor, thus protecting electrical systems from sudden surges during motor startup. The star-delta starter is specifically designed for squirrel-cage induction motors, which are typically designed to run with a delta-connected stator winding under normal operation. Basic Working Principle The star-delta starter initially connects the stator windings of the motor in a star (wye) configuration during startup. Once the motor reaches around 80% of its rated speed, the connection switches to a delta configuration. This reduces the inrush current and starting torque during the startup phase. The inrush current is a significant concern, especially for large motors, as it can be 5-7 times the full load current. By using a star-delta starter, this current can be reduced to appro…