METHOD FOR REDUCING A MAGNETIC STRAY VECTOR FIELD OF A ROTARY UNIT WITH A MAGNETIC BEARING COMPRISING PERMANENT MAGNETS BY PROVIDING A COMPENSATING MAGNET, ROTARY UNIT AND VACUUM PUMP

PROBLEM TO BE SOLVED: To provide an improved method for reducing a stray vector magnetic field of a vacuum pump or a rotary unit for the vacuum pump so as to perform an important reduction of at least one component in the stray vector magnetic field or sometimes its compensation when the quality of magnetic characteristics of a plurality of permanent magnets forming a permanent magnet supporting part is remarkably changed.SOLUTION: A stray vector magnetic field is generated at least partially by at least one permanent magnet supporting part [90]. This permanent magnet supporting part is formed for rotatable supporting in opposite directions of a vacuum pump or a rotor (16) of a rotating unit and a stator, and at least one element (Kr) in the stray vector magnetic field is determined at a reference point (P) and a magnetic field (M) of a balance magnet is selected to reduce the element in the stray vector magnetic field in at least the reference point or preferably compensate it or change it in a long period of time.SELECTED DRAWING: Figure 1