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ENERCON E-40 Operating Instructions
Page 31 of 96 yaw control more than 3 left turns of nacelle
2 - 3 left turns of nacelle low wind
(v < 3,5 m/s) deviation of nacelle position to wind direction more than 8° left (1-min average) deviation of nacelle position to wind direction more than 8° right (1-min average) yaw operation right yaw operation left
2 - 3 left turns of nacelle low wind
(v < 3,5 m/s) more than 3 left turns of nacelle cable untwist right cable untwist right
Figure 7: Schematic representation of the yaw control cable untwist left cable untwist left
3.12 Untwisting of cables
The power and control cables of the E-40 are suspended in the tower in such a way that they are relieved of strain. In concrete towers they are hanging on steel cables and in steel towers they are guided over a pulley before being fastened to the tower wall with plastic clamps. In both cases the cables have enough freedom of motion to allow the nacelle to rotate several times about its own axis. If the nacelle rotates several times in the same direction, the cables gradually become twisted. The control system of the E-40 ensures that the cables are untwisted automatically.
The cable twist sensors are installed in the cable twist switch which is mounted near the access hatch of the nacelle. The sensors for detecting the cable twisting are connected to the yaw gear rim. Additionally a left and a right limit switch are installed which shut down the turbine if the yaw control does not respond to the switches for uncoiling the cables. This prevents any further twisting of the tower cables. The turbine is stopped and cannot be restarted automatically.
If the cables have been twisted by 2 or 3 turns, the control system takes advantage of the next period of low wind to uncoil the cables. Should this not be possible because of the wind conditions and the cables become twisted by more than three turns, the turbine is stopped and the cables are uncoiled irrespective of the current wind speed. This process takes about 25 minutes. After having uncoiled the cables, the turbine automatically starts again, provided there is sufficient wind.
During the uncoiling process the display indicates main status 21 (cable twisting).
The sub-status shows in which direction the cables are twisted and whether they are uncoiled at low wind speed or not.
Main status: 21 :
22 :
Cable twisted
Yaw control fault
Operation
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