Blades

• The blades are arguably the most important part of the turbine and are the parts which form the propeller. These catch the wind causing the rotor to rotate. Modern turbine blades are made out of aluminium and composite materials; previously they were made of steel which was too heavy to be efficient. The size and material makeup varies depending on the climate where the turbines will be. The size of the blades varies depending on the strength of the wind. If the winds in a certain location are consistently strong, then smaller blades are required. The largest currently in use are around 50 meters long.
  
  

Rotor

• The rotor is the central part of the propeller and is fixed via a freely rotating axle to the generator, which produces electricity. The size of the rotor depends entirely on the length and weight of the blades it has to support. It has a built-in optimum rotation speed that is specified depending on average wind speed to ensure the blades do not spin too slowly or too quickly.
  
  

Yaw Motor

• As the wind does not consistently come from the same direction it is important for the turbine to be able to move to face the wind. The yaw motor is located just below the horizontal part of the turbine at the top and is used to rotate the propeller toward the wind. The location and design of the motor varies between the turbine manufacturers. Some turbines also have a pitch control that alters the vertical position of the blades. This is most commonly found on turbines where the wind speed varies widely so the blades can be positioned so they are almost horizontal to the ground. This is a protection system to stop the blades turning too fast.
  
  

Low-Speed Shaft and Gear Box

• The low-speed shaft and gear box are located behind the blades and rotor and regulate, to a certain extent, how fast the turbine actually turns. If the blades rotate too fast, they are not efficient at producing power, so the low-speed shaft is designed to only do a certain number of rotations a minute depending on the gear box setting. For example, if the wind is low, the gear box will be in a low gear allowing the blades to rotate freely. In very windy weather, the gear box is in a high gear so the blades do not turn too quickly. The low-speed shaft is made from high quality steel and the gear box from a variety of metals and composites.
  
  

High-Speed Shaft and Generator

• The gear box is connected to the high-speed shaft via a cog. This in turn is connected to the generator, which turns the rotation of the blades caused by the wind into electricity. The high-speed shaft is made out of high-quality steel and the generator from a range of metals and composites.