Placement of vents to reduce shaft flux in two pole induction motors with a comment on heating effects

The authors consider the problem of magnetic flux variation in the rotors of vent-cooled, two-pole induction machines. The solution to this problem is important not only to reduce stray losses in such machines but also to identify the location of hot spots to estimate their effects on the design. A second objective behind the research was to reduce the magnitudes and, as a result, the variations in shaft magnetic fluxes. Reducing shaft fluxes will result in reduced shaft failures due to fatigue that is exacerbated by repeated heating and cooling. A procedure is suggested for examining the effects of the placement of the vent holes on flux variations, especially in the shaft. Once the effects of flux variations are known, the heating effect can be deduced.>