A cooling fan includes: a fan housing; a rotation shaft rotatably supported in the fan housing; a stator fixed to the fan housing; a rotor, which is provided with a magnet that is disposed with a predetermined gap away from the outer circumferential surface of the stator, and which has an impeller connected thereto; and a printed circuit board (PCB) which is installed on a lower side of the stator, and is equipped with a circuit component for controlling the cooling fan and a Hall sensor for sensing the revolutions of the rotor. In order to increase the sensing power of the Hall sensor, the magnet is formed such that the length or the width of the magnet at the lower part thereof that is adjacent to the Hall sensor is larger than that of the other parts of the magnet.

A yaw sensor for a wind turbine is described. The yaw sensor comprises a rotary switch, configured to be coupled to a yaw drive gearbox of a wind turbine nacelle, the rotary switch being operable to activate and deactivate an electrical contact in dependence on an amount of yaw rotation of the nacelle relative to a start position. The electrical contact is active at a plurality of first yaw rotation ranges with respect to the start position, and inactive at a plurality of second yaw rotation ranges with respect to the start position, the first and second yaw rotation ranges being interleaved, at least some of the first yaw rotation ranges having different lengths from each other and/or at least some of the second yaw rotation ranges having different lengths from each other. The electrical contact generates an electrical signal when active.

A system for monitoring the axial position of a rotating shaft includes a phonic wheel mounted coaxially to the shaft for rotation with a circumferential row of teeth. The system includes a sensor configured to detect the passage of the teeth by generating an alternating measurement signal. First and second portions of the teeth alternate around the row and contribute respective first and second components to the alternating measurement signal. The first portion of teeth vary in height in an axial direction of the wheel such that the relative height of the first and second portions varies with axial distance across the phonic wheel, and the sensor is positioned relative to the phonic wheel such that axial displacement of the shaft causes the signal to vary the first component's amplitude relative to the second component's amplitude due to the height variation, to monitor the axial position of the shaft.

A monitoring system for monitoring the axial position of a rotating shaft includes a phonic wheel which is mounted coaxially to the shaft for rotation therewith. The phonic wheel includes a circumferential row of teeth. The system further includes a sensor configured to detect the passage of the row of teeth by generating an alternating measurement signal. The teeth are configured around the row such that the teeth contribute a component to the alternating measurement signal. The teeth are tapered in an axial direction of the wheel and the sensor is positioned relative to the phonic wheel such that, in use, axial displacement of the shaft causes the signal generated by the sensor to vary either or both of the amplitude and the pulse width of the component, whereby the axial position of the shaft can be monitored.

The invention concerns a method of operating a wind power installation in which the rotor is brought to a halt and fixed, comprising the steps: braking the rotor, positioning the rotor at a stopped position, and fixing the rotor in the stopped position. According to the invention it is provided that an end position is predetermined, the rotor is braked in regulated fashion to a stopped position associated with the end position, and for positioning for the predetermined end position the rotor is braked in an automated procedure until stopped at the stopped position, and for fixing in the stopped position a mechanical fixing device is applied, in particular automatically.

A measuring system for determining a torsion of a rotor blade, comprising a reference shaft to be arranged in the rotor blade in the longitudinal direction of the blade, at least one support for the reference shaft, for freely bearing the reference shaft in the rotor blade, so that the rotor blade can twist freely about the reference shaft, so that the reference shaft does not twist when there is twisting of the rotor blade, at least one rotary sensor, arranged on the reference shaft, for detecting a twisting of the rotor blade about the reference shaft in the region of the rotary sensor, the rotary sensor outputting a rotational angle describing the twisting of the rotor blade in relation to the reference shaft, or some other corresponding variable. A method for determining a torsion of a rotor blade, a corresponding rotor blade, a method for arranging a measuring system in a rotor blade and a corresponding wind power installation with a rotor blade and also or alternatively a measuring system.

A yaw sensor for a wind turbine comprises a plurality of rotary switches, each configured to be coupled to a yaw drive gearbox of a wind turbine nacelle, the rotary switches each being operable to activate and deactivate respective associated electrical contacts in dependence on an amount of yaw rotation of the nacelle relative to a start position.

Each electrical contact is active at a plurality of first yaw rotation ranges with respect to the start position, and inactive at a plurality of second yaw rotation ranges with respect to the start position, the first and second yaw rotation ranges being interleaved.

A wind turbine, a method and a control system for aligning a nacelle of a wind turbine with a target yaw angle is provided, wherein the control system includes a detection device configured for detecting at least one parameter indicative of wind forces acting on at least one component of the wind turbine for determining a current yaw angle of the nacelle, and an actuation device configured for manipulating a position of the nacelle until the current yaw angle is aligned with the target yaw angle, wherein the detection device includes at least one first bending moment sensor on a first component, wherein the detection device is configured for determining a bending moment of the first component based on data received from the first bending moment sensor as the at least one parameter indicative of wind forces acting on the at least one component of the wind turbine.

Provided is a method of estimation of rotor operational characteristics, in particular rotor speed, rotor azimuth and rotation direction, of a rotating rotor of a wind turbine, the method including: measuring pulse rising edge time and pulse falling edge time of pulses generated by each of multiple proximity sensors originating from multiple detection targets arranged on the rotor; estimating values of parameters associated with the sensors and/or targets, in particular parameters associated with the positioning and/or detection range of at least one sensor and/or the parameters associated with the positioning and/or size of at least one target, based on the measured pulse rising edge times and pulse falling edge times; estimating rotor operational characteristics, in particular a rotor speed and/or a rotor azimuth and/or a rotation direction, based on the measured pulse rising and/or falling edge times and/or the estimated values of parameters associated with the sensors and/or targets.

A method of determining at least one of a rotational angle position and a rotational speed of a rotating element of a drive train includes arranging at least two sensors in an offset manner in a circumferential direction of the rotating element, recording a measured value indicative of a characteristic of a rotation of the rotating element with each sensor, and determining at least one of a rotational angle position and a rotational speed with reference to the measured values and a distance between the at least two sensors in the circumferential direction.