The measurement and indexing of unbalanced magnetic pull in electrical machines

Unbalanced magnetic pull in cylindrical electrical machines has been studied by several authors but it can be hard to quantify and measure. This paper reviews some of the work related to UMP calculation and measurement and develops the concept of a UMP index in order to allow comparative studies. This is because the UMP can vary greatly in terms of magnitude depending on the type and topology of the machine and also the loading. Methods for measurement of UMP are also discussed and results put forward from a UMP measurement rig.