Effects of grain size and frequency on eddy current loss in Si-Fe sheets

The effect of frequency on eddy current loss was studied for nonoriented Si-Fe sheets of different grain sizes. In high-frequency regions, the eddy current loss accounts for a larger proportion of the core loss than in low-frequency regions; hence, the smaller the grain size, the smaller becomes the core loss. The eddy current loss is strongly influenced by the skin effect, especially in a weak magnetic field. This skin effect can be estimated using the Bozorth formula