Tooth frequency losses in rotating machines

Data are presented showing the hysteresis and eddy current losses due to minor displaced hysteresis loops superimposed on major loops of various amplitudes. In all cases the amplitude of the minor loops is made proportional to the displacement which approximates the conditions which occur in machines. These data are applied to the case of the induction motor having a sine wave field distribution and a sample case worked out showing that the hysteresis losses in the teeth due to the tooth pulsations may be of the same order of magnitude as the losses due to the fundamental frequency. The eddy current losses in thin sheets due to the high-frequency pulsations are in general negligible but may be quite appreciable in the pole faces where the sheets are thicker. There are of course other losses due to tooth pulsations such as eddy current and circulating losses in the copper, etc., but these are beyond the scope of the present investigation.