Single or multi-step resistors are connected upstream of the three-phase squirrel-cage motors to reduce the starting current and torque.

With single-step starters, the starting current is approximately three times the motor full-load current. With multi-step starters, the resistors can be so designed that the starting current is only 1.5 to 2 times the motor full-load current, with a very low level of starting torque.

This type of starting is preferable where the same starting torque is to be obtained as with the primary resistance starters but the starting current taken from the mains is to be further reduced. A reduced voltage U_a (approximately 70 % of the rated operational voltage) is supplied to the motor when starting via the starting transformer. Thus, the current taken from the mains is reduced to approximately half the direct starting current.

Resistors are connected in the rotor circuit of the motor to reduce the starting current of motors with slip-ring rotors. The current taken from the mains is thus reduced. In contrast to stator resistance starters, the torque of the motor is practically proportional to the current taken from the mains. The number of steps of the automatic starter is determined by the maximum permissible starting current and by the type of the motor.