Description:
A star-delta starter (often written as star-delta starter) is an electrical device used to start three-phase induction motors while reducing the starting current. It is commonly used in industrial applications where large motors are involved. The starter consists of three contactors (main, star, and delta), a timer, and an overload relay, all working together to control how the motor is connected to the power supply during startup.

Operation:
The star-delta starter begins by connecting the motor windings in a star (Y) configuration when the start button is pressed. This reduces the voltage applied to each winding, which lowers the starting current and torque. After a short time delay set by the timer, the starter automatically switches the connection from star to delta (Δ) configuration. In the delta mode, the motor receives full supply voltage and operates at its normal speed and power. The overload relay continuously monitors the current and will disconnect the motor if an overload or fault occurs, protecting the motor from damage.