A wind turbine converts the energy in the wind into electrical power. The turbine consists of three main elements:
The tower is made of steel and is set in a concrete foundation block below ground level.
The numbers of rotor blades can vary but there are usually 3 rotor blades per turbine, which are made of glass fibre-reinforced plastic (GRP) and are connected to a hub on the nacelle. The nacelle is the large box shaped enclosure located on top of the tower.
The hub (which the blades are attached to) is in turn connected to a gearbox and generator, both located inside the nacelle.
The wind direction and wind speed are constantly monitored by a sensor positioned above the nacelle. When the wind direction alters, the nacelle is rotated by hydraulic motors so that the rotor blades face into the wind to maximise the energy captured. There are two braking systems on the turbine, one on the blade tips themselves and the other is a disc brake connected to the high-speed shaft within the nacelle. The turbines have a remote control and communication system, which allows monitoring, data collection and a start/stop facility all by remote control.
The turbines usually start to operate when the wind is blowing at around 3.5m/s and shut down if the wind reaches speeds above 25m/s. As the wind speed reaches the start limit, the blades rotate and spin the drive shaft. The generator is connected to the drive shaft and converts the mechanical energy captured from the wind into electrical energy. The generator produces power at 690v, which is transformed to a higher voltage usually 20kV or above. The electricity then flows into the local electrical grid.