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ENERCON E-40 Operating Instructions
Page 11 of 96
1.5 E-40 Safety System
The safety system guarantees a safe operation of the turbine according to the requirements of international standards and of independent institutes such as Germanischer Lloyd or TÜV.
1.5.1 The Brake System
ENERCON wind energy converters feature aerodynamic brakes only. This way of braking reduces the driving forces and moments on the turbine when braking the rotor and in return "softly" reduces the speed of the turbine. Even when not in operation, the rotor is not locked. The turbine is allowed to idle, but only at a very low speed since the rotor blades are adjusted in feathered position. Rotor and drive train remain practically free of load.
A complete locking of the rotor is only actuated when using the emergency-stop switch or in case of maintenance work. Then an additional rotor brake (hydaulic disc brake) is used, which is applied only after the rotor has already been braked to some degree by the blade pitch control.
The three mutually independent blade pitch drives are used for operational braking to bring the blades into feathered position ("pitch the blades out of the wind") in only a few seconds. The aerodynamic forces at the blades are lost and the rotor speed is rapidly decreased. It is important to note that in order to reduce the rotor speed to a safe level, it would be sufficient to pitch just one of the three blades out of the wind.
In an emergency (e.g. in case of a failure of the utility grid), each rotor blade will be moved safely into feathered position by its own battery-buffered pitch drive. The availability of the batteries is ensured by regular battery checks and by automatic charging. The actuation of the blade pitch units via their emergency units occurs synchronously by electromechanic linking.
The combination of a redundant power supply for the case of emergency (grid or battery) with three totally autonomous pitch drives offers a safety concept which perfectly meets with the requirements for two completely independent ("fail-safe") braking systems.
1.5.2 Lightning Protection System
The E-40 is equipped with the ENERCON lightning protection system that deflects possible lightning strokes without causing any damage to the turbine. A lightning stroke is deflected from the rotor blade tip (or from the nacelle top, respectively) down to the earth surrounding the foundation.
The rotor blade tip is made out of aluminium. Along the leading and trailing edge of the rotor blade an aluminium profile is embedded directly under the surface.
These profiles connect the aluminium tip with an aluminium ring placed around the blade root near the blade flange. This ring has a sufficient distance to the conducting components of the root section so that hub and rotor bearings are protected against any consequential damage.
Short description of the E-40
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