A wind turbine is a mechanical device that converts the energy of the wind into electricity. Wind turbines designed to convert the energy of the movement of the wind (kinetic energy) into mechanical energy, movement of an axis. Then in the turbine generators, this mechanical energy is converted into electricity. The electricity generated can be stored in batteries, or use directly. There are three basic physical laws that govern the amount of usable energy from the wind. The first law States that energy generated by the turbine is proportional to the speed of the wind to the square. The second law indicates that the power available is directly proportional to the swept area of pallets. The energy is proportional to the square of the length of the vanes. The third law indicates that there is a maximum of wind generators from 59% theoretical efficiency. In practice, the majority of wind turbines are much less efficient than this, and are designed various types to obtain the maximum possible efficiency at different wind speeds. Best wind generators have efficiencies of 35% to 40%.
In practice the wind turbines are designed to work within certain wind speeds. The lowest speed, called cutting speed lower which is usually 4 to 5 m/s, because below this speed there is not enough energy to overcome the loss of the system. The higher cutting speed is determined by the capacity of a machine in particular withstand strong winds. The rated speed is the speed of the wind to which a particular machine reaches its maximum rated power. Above this speed, you can count on mechanisms to maintain the power output at a constant value with the increase in the speed of the wind.