supplied with this primary voltage gs the asynchronous motor m1 receives the primary voltage gs for a run up period which is pre set and monitored by the soft start control apparatus sas the duration of the run up time is derived from the electrical parameters of the motor at the end of the run up time which is recognized by the soft start control apparatus sas and is transmitted to the machine command center mz the contactor k1 is closed and the contactor k2 opened simultaneously via the machine command center mz this process may take approximately 5 seconds as a result the asynchronous motor m1 is supplied from then on directly via the network voltage ns the machine command center mz now actuates the contactor k4 and the soft start control apparatus sas and then the soft start of the asynchronous motor m2 begins the soft start control apparatus sas is sized for the highest starting current reached by one of the asynchronous motors m1 to m5 being used when the run up time for asynchronous motor m2 is ended the soft start control apparatus sas recognizes that the primary voltage gs has reached the magnitude of the network voltage.