The Calculation of Unbalanced Magnetic Pull in Synchronous and Induction Motors

Unbalanced magnetic pull may be defined as the net sideways force between the stator and rotor of an electric machine resulting from a difference in the air-gap flux densities on opposite sides of the machine. This difference in flux density is, in general, caused by a difference in the air gaps on the two sides. There is outlined herein a method of calculation of unbalanced pull which takes into account the combined effects of saturation, parallels, and primary reactance. The increased accuracy which this method affords should make possible more accurate predictions of mechanical deflections and critical speeds.