Wind Turbine Yaw Sensor Operation
Let’s take closer look at a typical sensor for a large wind turbine. The sensor mounts to the main frame; its gear is driven by the yaw ring.
![](https://i0.wp.com/windmillstech.com/wp-content/uploads/2022/11/encoder-disk-1.webp?resize=471%2C273&ssl=1)
This sensor employs an incremental encoder that tracks nacelle position, along with a group of limit switches dedicated to cable twist control
![](https://i0.wp.com/windmillstech.com/wp-content/uploads/2022/11/limit-switches-1.webp?resize=474%2C270&ssl=1)
Here we can see the terminal connections for Channel A and Channel B of the encoder. The outputs of the four limit switches are labeled Cam 1, 2, 3, and 4.
![](https://i0.wp.com/windmillstech.com/wp-content/uploads/2022/11/terminal-connections.webp?resize=466%2C266&ssl=1)
The cams are shown here. The drive gear rotates the cams, which activate switches that send signals to the controller.
As the drive gear turns, the cams work the switch-es. For this demonstration the gear is turning much faster than normal.
![](https://i0.wp.com/windmillstech.com/wp-content/uploads/2022/11/cams.webp?resize=472%2C267&ssl=1)
Here we can see the switches that are activated or deactivated
![](https://i0.wp.com/windmillstech.com/wp-content/uploads/2022/11/switches.webp?resize=479%2C265&ssl=1)
![](https://i0.wp.com/windmillstech.com/wp-content/uploads/2022/11/cam-positions.webp?resize=790%2C439&ssl=1)
Each cam serves a different purpose.
- Cam 4 presses on its switch when the nacelle has rotated between 2.3 and 5.1 turns counter-clockwise.
- Cam 3 indicates clockwise rotation of 2.3 to 5.1 turns.
- Cam 2 counts each revolution.
- The switch for Cam 1 is activated at all times until the nacelle has rotated 4.7 turns in either di-rection.
![](https://i0.wp.com/windmillstech.com/wp-content/uploads/2022/11/switch-output.webp?resize=697%2C352&ssl=1)
The output of the four switches is combined and sent to the controller. The table shows the switch-es that are assigned to each bit, the standard values and their meanings. Notice that the output from Switch 105 may be either a zero or a one in any of the described states. Values that are not listed on the table will trigger a yaw sensor error alarm
![](https://i0.wp.com/windmillstech.com/wp-content/uploads/2022/11/cams-timing.webp?resize=455%2C254&ssl=1)
The cam timing can be adjusted by loosening the release screw and rotating the cams
![](https://i0.wp.com/windmillstech.com/wp-content/uploads/2022/11/callibration-diagram.webp?resize=918%2C311&ssl=1)
Proper adjustment is shown on a calibration diagram. Cams must be calibrated during commission-ing, but may also need to be adjusted if an error alarm occurs
Nacelle’s position is also tracked by an incremental encoder. This encoder generates two thousand seventy-four pulses for each revolution of the nacelle. Clockwise rotation from the initial position of zero adds to the position signal, counter clock-wise rotation subtracts from it
![](https://i0.wp.com/windmillstech.com/wp-content/uploads/2022/11/Nacelle-position.webp?resize=444%2C258&ssl=1)
The controller calculates position in degrees based on this information. A proximity switch is used to reset the degree position to zero each turn. The target for this switch is installed with the nacelle facing North, allowing the PLC to calcu-late azimuth from true North on each revolution.
![](https://i0.wp.com/windmillstech.com/wp-content/uploads/2022/11/target-proximity-switch.webp?resize=436%2C194&ssl=1)
![](https://i0.wp.com/windmillstech.com/wp-content/uploads/2023/02/High-land-Community-College.webp?resize=200%2C200&ssl=1)
Highland Community College as part of WindTechTV.org