Siemens is testing a new gealess conzept for wind turbines The purpose of the installation is to evaluate if the Direct Drive technology may be competitive with geared machines for larger turbine sizes.

The main advantage is in the simple design which manages with fewer machine components. Because gearless systems have fewer rotating machine components, this technology was able to reduce maintenance expenses and increase the availability. A gear usually transforms the low speed of the wind rotor to the high speed for generating electricity.

The gearless test systems, on the other hand, have synchronous generators which are excited by so-called permanent magnets. They transform the rotor movement directly into electrical power. The generators of the gearless wind turbines are some of the biggest permanent magnet machines ever to be built. They have rotational torques on a scale of 2,500 kNm.

By comparison: a strong electric drive for a vehicle has much less than 1 kNm torque. One area of focus of the technology project will be on possible offshore applications.  Because wind farms at sea have to be robust and reliable.