star-delta starting is the best known system and perhaps the commonest starting system at reduced voltage; it is used to start the motor reducing the mechanical stresses and limiting the current values during starting; on the other hand, it makes available a reduced inrush torque.This system can be used for motors with terminal box with 6 terminals and double supply voltage. It is particularly suitable for no-load starting or with low and constant load torque or lightly increasing load torque, such as in the case of fans or low power centrifugal pumps.