Temperature dependence of loss separation measurements for oriented silicon steels

Loss separation measurements were made over the temperature range of 20 to 200°C for 0.22-mm and 0.29-mm thick regular grain oriented (RGO) and 0.31-mm thick high permeability oriented (HGO) Epstein samples. The 0.22-mm thick RGO sample had only a forsterite coating, while the thicker samples had secondary high stress coatings. Over the temperature range of 20 to 100°C the change in hysteresis loss P
h
with temperature was negligible for all samples. Since the total core loss P
T
decreased with increasing temperature over this range, almost all the loss reduction was due to a reduction in the eddy current loss component P
e
which was inversely proportional to the resistivity. The eddy current loss anomaly factors η exhibited little variability with increasing temperature, indicating that domain wall spacings did not change with increasing temperature.