Fact Sheet - Wind Turbines by JoeyVagana


									Fact Sheet - Wind Turbines.
 How wind turbines work
 The majority of      wind turbines producing electricity consist of     rotor
 blades   which    rotate around    a  horizontal hub,   although,   several
 companies have developed or in the process of developing “helix” style
 designs that rotate vertically around a central hub. The hub is
 connected to a generator with a direct drive, which are located       inside
 the nacelle. The nacelle houses the electrical components and is
 mounted at the top of the tower. This type of turbine is referre d to as a
 'horizontal axis' machine.
 Rotor diameters range up from a couple of meters on Small Scale Micro
 Generation Projects up to 80 metres on the wind farmers we see j otted
 around the countryside. Most wind turbines have three rotor blad es,
 although,    depending    on   the   manufacturer   and    their  technical
 specifications various options are available to the consumer in the
 marketplace. Most designs have three blades and are made of
 fibreglass -reinforced polyester or wood    -epoxy.
 The speed at which they rotate generally depends on the size of the
 generator and can range between 400 to 150 revolutions per minut e at
 constant speed, Power is controlled automatically as wind speed       varies
 and machines will be     be automatically stopped at very high wind speeds
 to protect them from damage.
 A yaw mechanism is used to turn the turbine face into the wind,       while,
 on some models sensors are used to monitor wind direction and the
 tower head is turned to line up with the wind.
 One of the crucial parameters concerning your choice of turbine        is the
 diameter of the rotor blades - the longer the blades, the larger the area
 'swept' by the rotor and the greater the energy output.
 There are many different turbine designs, with plenty of scope f or
 innovation and technological development. Our partners we believe
 offer advanced and robust design at a highly competitive price.
 Stall and pitch control.
 There are two main methods of controlling the power output from the rotor
 blades. The angle of the rotor blades can be actively adjusted b y the machine
 control system. This is known as pitch control. This system has built-in
 braking, as the blades become stationary when they are fully 'fe athered'.
 The other method is known as stall control. This is sometimes kn own as
 passive control, since it is the inherent aerodynamic properties of the blade
 which determine power output; there are no moving parts to adjus t. The twist
 and thickness of the rotor blade vary along its length in such a way that
 turbulence occurs behind the blade whenever the wind speed becom es too
 high. This turbulence means that less of the energy in the air i s transferred,
 minimising power output at higher speeds. Stall control machines also have
 brakes on the blade tips to bring the rotor to a standstill, if the turbine needs to
 be stopped for any reason.
 Most wind turbines start operating at a speed of 3 -4 metres per second and
 reach maximum power at about 12.15 m/s
 Important Factors to consider that will affect the performance
 of your Wind turbine.
 1.   Most important is the wind speed at the site. The power availabl e from the
      wind is a function of the cube of the wind speed. Therefore a doubling of the
      wind speed gives eight times the power output from the turbine. All other
      things being equal, a turbine at a site with an average wind speed of 5 meters
      per second ( m/s ) will produce nearly twice as much power as a turbine at a
      location where the wind averages 4m/s
 2.   The availability of the equipment. This is the capability to operate when the
      wind is available an indication of the turbine's reliability. This is typically over 98%
      for modern machines.
      Last is turbine arrangement. Turbines must be carefully positioned away from
      obstructions and potential windbreaks to gain the maximum energy from the wind.


  ext and figures based on a fact sheet produced by the European Wind Energy Association

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