Dependence of losses on flux density in grain oriented 3% silicon steel

Samples of conventional and high permeability grain oriented 3% silicon-iron were tested at flux densities of 1.0, 1.3, 1.5 and 1.7 T. The losses of selected samples were also measured at magnetizing frequencies of 30, 40 and 50 Hz in addition to 60 Hz. Results show that losses increase simply as the square of induction from 1.0 to 1.3 T regardless of sample history, degree of texture perfection, thickness, or grade. Such a dependence of losses on flux density is predicted by all domain theories of eddy current losses in these materials. However, such a simple dependence of losses on the square of flux density does not persist up to 1.7 T. Instead, losses at 1.7 T are offset from a theoretical B²dependence by a constant amount (Δ Ps) which depends only on the degree of texture perfection (i.e., μ10 or B at 800 A/m). This some what surprising result is true regardless of sample history, sheet thickness, grade, or frequency. The origin of this effect is discussed and factors affecting low induction core loss are summarized.