The start delta starting is a very common type of starter and extensively used, compared to the other types of the starters. This method uses reduced supply voltage in starting the connection of 3 phase induction motor with a star delta starter.
The method achieved low starting current by first connecting the stator winding in star configuration, and then after the motor reaches a certain speed, throw switch changes the winding arrangements from star to delta configuration
By connecting the stator windings, first in star and then in delta, the line current drawn by the motor at starting is reduced to one-third as compared to starting current with the windings connected in delta Since the torque developed by an induction motor is proportional to the square of the applied voltage, star-delta starting reduced the starting torque to one-third that obtainable by direct delta starting where,
K2M Main contactor
K3M Delta contactor
K1M Star contactor
