Rotational movement control of an electric generator by means of a turning device

An electric generator for a wind turbine, the electric generator comprising:

• a stator assembly;
• a rotor assembly being rotatably supported at the stator assembly for rotating around a rotational axis;
• an annular device being fixed to the rotor assembly and comprising an engagement structure;
• and
• a first turning device being mounted to the stator assembly, the first turning device comprising an actuator and an engagement element being drivable by the actuator;
• wherein the first turning device is configured for adopting two operational states, an active operational state, and a passive operational state, wherein:
• (i) in the active operational state there is an engagement between the engagement element and the engagement structure, and
• (ii) in the passive operational state, the engagement element and the engagement structure are mechanically decoupled from each other.