Factors affecting the eddy-current loss in steel clamping bolts

A solution is presented for the eddy-current loss occurring in a solid steel cylinder surrounded by an air gap, owing to the application of a uniform pulsating m.m.f. This approximates to the practical condition of a steel clamping bolt inserted in a laminated machine core. It is shown that the demagnetising effect of the eddy currents is important within the region of practical interest. Curves are drawn which illustrate the relative importance of the various parameters in determining the loss. The presence of even a small gap is a dominating influence.