legends · 4 min read ·
Turbine 7
A wind farm technician finds a hand crank bolted to a turbine that is exporting power with no wind.
**Carrow Fell Wind Farm — Maintenance Log, Turbine 7 (2.5 MW)**
**Technician:** L. Pryor · **Date:** 11 October
**09:10.** Arrived at base. Wind 9 m/s from the south-west. Rotor turning clockwise, correct direction, 14 rpm. Output 1.8 MW.
**09:40.** Climbed to nacelle. Gearbox oil clean. Yaw drive working. Blade pitch nominal.
**10:15.** Checked blade roots. Blade B shows a hairline crack at the root flange. Logged for repair. No action today.
· · ·
**SCADA alarm extract (Turbine 7, 12 October)**
- **Time · Alarm · Value**
- 02:11 · Wind direction vs. nacelle yaw error · 180°
- 02:11 · Rotor direction reversed · −9 rpm
- 02:12 · Wind speed · 0.0 m/s
- 02:12 · Power export · +14 kW
*Turbine turning backwards in dead calm, exporting power. Possible sensor fault.*
· · ·
**Maintenance log, 13 October (L. Pryor)**
Climbed to the nacelle at dawn. Anemometer, wind vane, and encoder all working. The rotor was turning slowly against the wind, three revolutions a minute, in air that was absolutely still. The other turbines on the ridge stood idle.
I put my hand on the main shaft. It was warm and turning steadily. It was not being driven by the gearbox. The brake was off and the generator was disengaged. The shaft turned of its own accord, with a faint thrum I could feel through the soles of my boots, like a pulse.
· · ·
**Maintenance log, 14 October**
Isolated Turbine 7 from the grid. Locked the rotor with the brake pin. The pin snapped.
I fitted a new pin. It snapped again, at the same place, a clean shear. I put the rotor lock on, two pins, a hydraulic hold. The rotor stopped. For the first time in three days, the nacelle was silent.
I sat on the floor of the nacelle for a minute, listening. The wind was nothing. The tower was still. Then, from inside the hub, very faint, I heard a sound I know from my grandfather's workshop. A hand turning a wheel. A slow, patient wheel, being turned by hand because the engine has failed.
· · ·
**SCADA alarm extract (Turbine 7, 15 October)**
- **Time · Alarm · Value**
- 03:30 · Rotor lock status · **RELEASED**
- 03:30 · Rotor · −11 rpm
- 03:31 · Power export · +96 kW
- 03:40 · Power export · +310 kW
- 04:15 · Power export · +880 kW
*Turbine 7 is exporting power with no wind and the grid isolator open. Export meter shows power flowing from the turbine to the grid, through an isolator that is open.*
· · ·
**Maintenance log, 16 October**
Called out with the site manager. We opened the hub cover with a hydraulic jack. The hub is a sealed steel space, 3 m across, with a ladder to the pitch bearings.
In the hub, on the bearing housing, someone has been working. There is a bench vice, bolted down with new bolts. A set of hand tools laid in a row on a cloth. A thermos. A coat folded on the cover of the slip ring. In the centre, a hand-crank, bolted to the main shaft, with a worn leather grip.
The crank handle was warm.
· · ·
**Site manager's memo (Carrow Fell, 18 October)**
Turbine 7 has been removed from service. The site has been closed to staff. We have investigated and cannot account for the hand crank, the tools, or the power it appears to have exported. The turbine has been exporting at 880 kW, steady, for three days with no wind.
The grid operator has asked whether we could keep it running. Output at this level is worth £1,100 an hour.
· · ·
**Maintenance log, 22 October (L. Pryor, final entry)**
I have refused to climb again. But I have read the logs. The power export has been steady at 880 kW for six days. It does not depend on the weather. It has not changed with the time of day.
What I cannot get out of my head is the hand on the crank. Whoever turns it is doing the work of a 2.5-megawatt turbine, by hand, from inside a sealed steel hub, in the dark. To do that for six days a person would need to be doing something that no body could do.
I have written to the manager. I have said that it is not the turbine that is exporting. It is the person, and the grid has been asked to take what they give. I have said that someone should go up and relieve them.
The manager has replied. He says that the export has stopped. At 05:40 this morning, the power fell to zero. The turbine is silent. The crank has been left in the hub, still warm, and beside it a note on a clean white card, in pencil.
*Thank you for the shift. Please send the next one.*