Concentricity

As shown in fig. (a) below, when the center of a motor's stator, rotor, and shaft are aligned, the state is called concentric. A state where one or more is shifted is from this central position is called eccentric. In fig. (b), the centers of the stator and the rotor are offset. Fig. (c) is an eccentric state in which the center of the outer periphery of the rotor is offset from the center of the shaft. The level of concentricity is expressed in mm or microns.