Patent ID: 7919947

Claim:
Method for starting an electric machine ( 10 ) with a magnetically mounted rotor ( 20 ), in particular for rotating the spinning cup of an open-end spinning machine, comprising the steps of: (a) magnetically supporting a rotor ( 20 ) via a magnetic bearing having permanent magnets ( 31 , 32 , 33 , 34 ), (b) controlling the position of the rotor in an axial direction ( 35 , 36 ) via an actuator system, (c) limiting the axial positioning of the rotor via two axial limitation bearings ( 41 , 42 ) defining first and second axial end positions of the rotor, (d) activating the actuator system for moving the rotor from the first axial end position, (e) when moving the rotor from the first end position, comparing a system variable with an associated reference value, (f) moving the rotor ( 20 ) into the second end position, (g) activating the actuator system for moving the rotor from the second axial end position, (h) when moving the rotor from the second end position, comparing a system variable with an associated reference value, and (i) generating a fault signal in the event of a previously established deviation of a system variable from an associated reference value.