The ALSPA CDM8000 type frequency converter with rated power up to 13.5MVA and higher serves for continuous speed adjustment of single medium voltage asynchronous motors. This drive system is designed for high-speed motors up to 15000 rpm and higher and for motor voltages up to 10kV, such as for gearless compressors but also for pumps, fans and so on. Already existing medium voltage motors can be extended to adjustable drive systems without derating, because the motor current is nearly sinusoidal. The simple functioning principle of the ALSPA CDM8000 makes it possible without additional technical measures to brake the drive electrically, regenerate its energy and change its rotating direction (4-quadrant operation). ALSPA VDM6000 and ALSPA VDM7000 frequency converters are also avalaible for medium voltage motors and ALSPA MV1000, ALSPA MD2000 and ALSPA CDL8000 for low voltage motors.