Abstract :
The paper deals with the variation of permeability and losses in ferromagnetic laminae over a frequency range from 0 to 3 × 106 cycles. After a brief description of test methods, results are given for four materials. The eddy loss observed at low frequency is shown to differ from the calculated loss, and an explanation of the effect is given. Medium-frequency performance is discussed briefly, and finally it is shown that at high frequency, permeability is influenced mainly by the depth of flux penetration in relation to the size of the selfsaturated magnetic regions. Evidence is offered tending to show that hysteresis loss is absent at high frequency, but that an increased eddy loss occurs at high frequencies from causes similar in origin to the increased loss at low frequencies.
