Why should we use the gear box?

Wind rotor rotary energy generated through the main shaft, gearbox and generator to the transmission of high-speed shaft?

Why should we use the gear box? Why can not we have a direct drive generator axis?

If we use ordinary generators, and the use of two, four or six electrodes directly connected to 50 Hz three-phase AC power line, we will have to use speed to 1000-3000 per minute to the wind turbine. The rotor diameter of 43 m wind turbine, which means the end of the rotor speed of more than twice the speed of sound is even higher. Another possibility is to build a number of electrodes with the alternator. But if you want a direct link in the electricity generator on-line, you need to use electrodes of 200 generators, to get to 30 per minute speed. Another problem is that the quality of the generator rotor and the need for proportional to the size of torque. Therefore, a direct-driven generators will be very heavy.

Lower torque and higher speed

The use of gear box, you can wind rotor on the low speed, high torque, converted to generators for the high speed, low torque. Wind turbine on the gear box, usually between the rotor and the generator with a single speed gear ratio. 600 kilowatts, or about 750 kilowatt machine, the gear ratio of about 1 to 50.