Let's look at the question of how you can start the induction motor?

There are different options associated with starting a motor and the common method is: Star-Delta starting. This method needs 3 contactors and a control part to manage the contactor sequence. Both ends of the motor windings must be accessible. Motor windings are connected in star formation upon starting. Once the motor torque matches the load torque, the winding connection is changed to delta connection.

Star/delta provides a softer start than direct-on-line but acceleration is still not controlled. Star/delta is always used for motors above 10kW to preserve and optimize the electric installation and mechanical parts. The motor is started with the Y (Star) connection and accelerated as far as possible, then switched to D(Delta)-connection. Notice how the star/delta connection causes a starting current of about one third the current associated with direct-on-line starting. This rupture in the star/delta starting current is the result of the starting current making the switch between star and delta.