Star Delta feeder Control Wiring ||practical using on Delay Timer 

Star delta starters are another device that may be used to reduce current demand during motor startup. It is often used for starting three-phase induction motors, but can only be used when starting the motor without load and when the required starting current is relatively low
The speeds of Star connected motors are slower as they receive 1/√3 voltage. The speeds of Delta connected motors are high because each phase gets the total of line voltage