High-speed motors with magnetic bearings could rival gas turbines

ABB has developed a range of high-speed, high-power motors designed to challenge gas turbine drives in applications such as compressors, pumps, and blowers. The motors, which use active magnetic bearings, are said to be more efficient, quieter, cleaner, smaller, safer, more reliable, and cheaper to run than turbines.

The motors, rated from 2-15MW, are designed to be used with ABB`s recently introduced ACS 6000 family of medium voltage drives. They will operate with a claimed efficiency of 96.5% over a speed range of 3,800-15,000 rpm.

Dr Brabara Frei, ABB`s project manager for the high-speed machines, claims that they are the first standard range to use active magnetic bearings. She says that because these bearings exhibit negligible friction, their losses will be around one fifth of those for conventional mechanical types.

The oil-free bearings do away with the need for lubricant pumps and piping, reduce the risk of fire, are more reliable, and cost less to maintain than mechanical bearings. They are also easier to control and monitor, Frei adds.

The annual cost of maintaining a gas turbine can be up to $54/kW. Frei estimates that the electrical alternative will cost just $13.4/kW to maintain, as well as reducing noise levels by 30dBA.

ABB has worked with the turbocompressor specialist Sulzer Turbo in developing the high-speed drives. Sulzer`s Andrew Marriott says that electrical drives "will bring competition to a previously monopolistic market".