Why is 690 volts used as a wind generator?

Answer 1

400 volts 3 phase is the standard voltage in Europe, and wind generators originated in Europe. 3 phase induction motors are readily available and become induction generators when driven faster than there syncronous speed mechanicaly by an external force, like the wind in the case of wind generators. Motors are typically delta connected and have 400 volt windings. In the case of generators there is an efficiency gain by configuring the 400 volt windings in a star configuration because the higher voltage will yield a lower current allowing a smaller diameter conductor. Square root of three times 400 volts equals 690 volts. Viola!

Answer 2

690 volts is a common voltage level used in wind generators because it strikes a balance between power transmission efficiency and equipment costs. It allows for efficient long-distance power transmission with lower losses compared to lower voltage systems, while also being compatible with standard electrical equipment. Additionally, 690 volts is a safe operating voltage that meets industry standards for wind turbine systems.