A wind turbine has to feature at least two independent safety systems in order to shut down the wind turbine to a safe state. Therefore, each blade has its own Battery Power Supply, which ensures independent power supply even after a total grid breakdown. In case of an emergency, the blades are pitched into the vane position which is the safe position. If the servo controller is not functioning well, this is detected by one of the three independent electronic circuits that overrules the servo controller. This electronic circuit regulates it’s blade into vane position on battery power. The total wind turbine can be brought to a safe situation even with one blade alone. Therefore the AWE 900 series turbine has three independent safety systems.