Patent ID: 8600570

Claim:
A system for triggering an emergency system of a wind turbine, the emergency system stops the wind turbine when triggered, the system comprising a sensor for sensing an acceleration value of a portion of the rotor of the wind turbine, the sensor is an accelerometer; an estimation unit coupled to the sensor, the estimation unit is adapted for receiving the acceleration value from the sensor and for estimating a rotor rotational speed value of the rotor of the wind turbine based on the acceleration value; a triggering unit coupled to the estimation unit, the triggering unit is adapted for receiving the estimated rotor rotational speed value, for determining the estimated rotor rotational speed value exceeds a predefined limit value and for triggering the emergency system, which comprises plurality of hydraulic valves, by activating a safety switch as a result of the determining; a first rotational speed sensor for sensing a first rotational speed value of the rotor, a comparator unit adapted for receiving the first rotational speed value from the first rotational speed sensor and for receiving the estimated rotor rotational speed value, wherein the comparator unit is further adapted for obtaining a comparison value based on a comparison of the first rotational speed value and the estimated rotor rotational speed value, and a detection unit adapted for determining the comparison value exceeds a speed sensor error.