Electric high-speed drives with magnetic bearings offer significant technical and economic advantages for gas compression and pipeline operation. Compressors with magnetic bearings and dry gas seals have been successfully used for more than a decade. These installations have demonstrated that the elimination of the compressor lube oil system results in increased availability and is economically viable. Nevertheless, as long as a lube oil system is still necessary for the drive or for a gearbox the benefits of oil-free operation such as increased safety and increased availability cannot be fully exploited. Electric high-speed drives do not require a gearbox. In combination with the use of magnetic bearings such drives allow the elimination of the entire lube oil system resulting in a dry rotor string. This results in increased efficiency and increased availability, and leads to reduced operation and maintenance cost. Furthermore, such electric high-speed drives can easily be adjusted to specific requirements, allow a wide operating range and thus the pipeline operation can be optimized. High efficiency, oil-free operation and no emissions make electric high-speed drives the most environmental friendly compressor drive.
The main disadvantage so far has been that electric high-speed drives and especially magnetic bearings needed high engineering effort resulting in high cost. The concept developed by ABB overcomes these problems with a modular approach for the motor and the power converter as well as for the magnetic bearings. Thus, electric high-speed drives have become a cost competitive, attractive solution for gas industry.