Rotational power losses in 3% SiFe as a function of frequency

Rotational power losses per cycle Pr/f have been measured as a function of rotational frequency f, between about 0 and 25 Hz, on grain oriented and isotro pic 3% SiFe, under different magnetization conditions, up to almost complete saturation. Loss measurements were performed from the rate of change of the angular velocity of a top, spinning freely in a uniform magnetic field, on which disk samples (diameter 19 mm, thickness 0.33 ram) were mounted. Maximum losses are found to occur for a relative magnetization M/Ms, which is of the order of 0.8 for all rotational frequencies. The results show that the behavior of Pr/f vs. f is characterized by large excess anomalies with respect to classical losses, except for M/Msclose to 1.0. On the other hand, the nonlinearity anomaly, typical of alternating loss curves, is absent since the rotational losses per cycle are found to increase linearly with f for all M/Msvalues.