Slip resistors are continuously switched in the rotor circuit of an asynchronous motor and result in an increased influence of load variation on the motor speed as well as in a limitation of the power surge under rising loads. A motor with an additional slip resistor of 4% will only reach 0.96 times its nominal speed at nominal load. The motor thus becomes “softer” and load reactions affecting the feed grid are attenuated. Slip resistors continuously cause additional losses in the rotor circuit of the drive.