Sensor checks
Proper functioning of all sensors is either regularly checked by the WEC control system itself dur‐
ing normal WEC operation or, where this is not possible, in the course of WEC maintenance work.
Speed monitoring
The control system of the ENERCON wind energy converter regulates the rotor speed by adjusting
the blade angle in such a way that the speed does not significantly exceed rated speed even dur‐
ing very high winds. However, this pitch control system may not be able to react quickly enough to
sudden events such as strong gusts of wind or a sudden drop of the generator load. If rated speed
is exceeded by more than 15 %, the control system stops the rotor. After three minutes, the wind
energy converter automatically attempts to restart. If this fault occurs more than five times within 24
hours, the control system assumes a defect and does not attempt any further restarts.
In addition to the electronic monitoring system, each of the three pitch control boxes is fitted with
an electromechanical overspeed switch. Each of these switches can stop the wind energy convert‐
er via emergency pitching. The switches respond if the rotor speed exceeds the rated speed by
more than 25 %. To enable the wind energy converter to restart, the overspeed switches must be
reset manually after the cause of the overspeed has been identified and eliminated.
Vibration monitoring
The vibration sensor serves to detect excessive vibrations and shocks such as might be caused by
a malfunction in the rectifier. It is mounted on the bottom of the main carrier of the wind energy
converter and consists of a limit switch with a spring rod that has a ball attached to one end by a
chain. The ball sits on top of a short vertical pipe. In the event of strong vibrations, the ball falls
from its seat on the pipe, activates the switch by pulling the chain and thereby initiates emergency
pitching of the rotor blades that stops the rotor.
Air gap monitoring
Microswitches distributed along the rotor circumference monitor the width of the air gap between
the rotor and the stator of the annular generator. If any of the switches is triggered because the
distance has dropped below the minimum distance, the wind energy converter stops and restarts
automatically after a brief delay.
If the fault recurs within 24 hours, the wind energy converter remains stopped until the cause has
been eliminated.
Safety system
D0376616-2 / DA 10 of 21
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