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Rotor - Bearings and Components

The rotor system converts the wind’s kinetic energy into a rotation, and so should be seen as the engine that finally drives the whole turbine. It is also the part of the turbine that is most exposed to all harsh weather conditions (rain, hail, lightning, hurricanes & typhoons), with extremely tight safety requirements.

The weight of the rotor assembly is critical, for several reasons.

Inertia: A high weight would be more difficult to bring into rotation by wind force.
Mechanical loads: A high weight would impose high loads on the yaw system, as rotor hangs at the upwind side, outside of the nacelle, and wants to ‘lean forward’.

Sub-systems within the Rotor

Rotor Hub
This is a large metal casting, which connects the 3 blades to the central shaft.
Blade Pitch Systems
These are the systems that allow the blades to be pitched (twisting of full blade over their length axis). Traditionally pitching was only performed at change of wind speeds, and all 3 blades pitched together. New systems however allow Individual Pitch Control (IPC) where blades can be pitched individually, and dynamic.

- Blade pitch bearings: Pitch bearing dimensions are similar as Yaw bearing dimensions, and so are loads.
- Blade pitch actuators can be either hydraulic or electrical.

Rotor Blades
Rotor blades can be seen as the sails that capture the wind, and are mostly made from glass-fiber reinforced thermosets.
Rotor blades must be very stiff, to prevent them from hitting the tower during a sudden wind gust. This extra stiffness is created by integrating “Spar Caps” inside the blade.
Lightning Protection System
Wind turbines are prone to being hit by lightning, due to their location and height. Lightning Protection Systems allow for controlled protection and can avoid damage to the blades.

Wind Turbine Section	Application Examples
Blade Pitching	Pitch Slide Bearings
	Pitch Roller Bearings
Blade Components	Blade Add-ons
	Blade Protection (erosion, lightning)
	Blade Spar Caps