Application of active magnetic bearings for identification of the force generated in the labirynth seal

A magnetic bearing system of a rotating shaft is characterized by a unique feature that consists in the possibility of monitoring static and dynamic loads (reactions) of each bearing under normal operation of the machine. In the paper, an identification procedure of bearing response forces, which allows for simultaneous measurement of the journal position with respect to the bush and the control currents that flow in magnetic bearing bush windings, is presented. The proposed procedure ensures effective protection of the rotating shaft supported in active magnetic bearings against too high loads and displacements that can occur in the rotating system. Experimental investigations were carried out on test rigs with the shaft supported in active magnetic bearings.