MOTOR STARTER TRANSFORMER

In order to limit the applied voltage to the motor a motor starter transformer with the voltage tapping of 50%,60% and 80% of nominal voltage is connected to the motor

With the auto transformer starting ,the line current is always less than the motor starting current since the motor is connected on the secondary side of the transformer

If the motor is connected to 50% tapping of the transformer the motor current will be reduced to 50% of nominal current value

Most of the motors are connected with 65% of line voltage. If the torque of the motor is not sufficient a high torque can be achieved with 80% tapping of the transformer.

Similarly if more torque is applied to the load with 65% tapping the torque can be reduced to 50%.