The frameless alternators of the ATK family have been designed for wind energy applications in direct drive technology without gearbox in the power range of 200W up to 100kW.
Six sizes with an OD of 145 to 795mm and an ID of 56 to 630mm and up to 9 stack length in each size are available. The OD of the stators is used for the model number: 145ATK, 190ATK, 300ATK, 400ATK, 500ATK, 800ATK.
For each model there are two standard windings for different speed characteristics. The typical speed ranges from 80 to 1500rpm depending on size. The windings are designed for a phase to phase voltage of 230Vac (133Vac single phase) at nominal speed and power. For the version with the higher speed the power is higher and therefore at the same voltage the current must be higher as well.
The frameless alternators ATK have the following main characteristics:
- Compact design and high power to weight and power to size ratio allow for usage in wind turbines in direct drive mode without gearbox: up to 600W/kg and 2,500W/dm3
- Low losses and high efficiency at low nominal speed: up to 94% efficiency in some models
- Wind turbine starts already at low wind speed due to very low «magnetical friction» or cogging: special design for only about 1% of nominal torque as cogging
- Excellent energy production already at very low speed by excellent power/speed curve: up to 50% of nominal power at half speed
- Highest reliability and life time: MTBF of up to 100,000 hours and more in standard applications.