A three-phase manual star delta motor starter is an electrical device used to start and control the speed of a three-phase induction motor. It is designed to reduce the starting current and torque of the motor, thereby reducing stress on the motor windings and increasing its service life.
The starter consists of two contactors, a timer, and an overload relay, all housed in a single enclosure. The contactors are used to switch the motor windings between star and delta configurations, while the timer is used to delay the switching of the contactors to prevent excessive current surges during the transition from star to delta. The overload relay is designed to protect the motor against overloads and short circuits.