A magnetic bearing is a bearing which supports a load using magnetic levitation. Magnetic bearings support moving machinery without physical contact.They can levitate a rotating shaft and permit relative motion with very low friction And no mechanical wear. They are in service in such industrial application as electric power generation, petroleum refining, machine tool operation and natural gas pipelines. 

A bearing is a machine element, which supports another movingmachine element. It permits relative motion between the contact surfaces of themembers, while carrying load.

Due to relative motion,friction occurs and rubbing surface wears rapidly. To prevent this a lubricant may be used. A question comes in mind whether it is possible to support ajournal without any physical contact so that there is no wear. Is there a force, whichcan exerted even if there is no contact between two-surfaces. Magnetic force allows suchproperty and thus the idea of magnetic bearingwas visualized. 

Already in 1842 Earnshaw had demonstrated that passive (permanent)could made but it cannot stable in all spatial direction. For successfuloperation the unstable direction have to be electrically served. Hence the name ACTIVE MAGNETICBEARING.