Alternating and rotational power loss at 50 c/s in 3% silicon-iron sheets

Alternating and rotational power losses at 50c/s have been measured at various flux densities for hot-rolled and cold-rolled 3% silicon iron in 0.013 in laminations, using an improved thermocouple method. The aim of the work was twofold: (a) to provide design data for the engineer on the magnitude of the power loss in various forms of 3% silicon iron under various flux conditions, ranging from a pure alternating flux to a pure rotating flux (b) to see how far the experimental results could be interpreted in terms of domain concepts. It has been found that, although the alternating losses along the rolling direction for the `four-square¿ and `Goss¿ oriented materials are about equal in magnitude, the rotational loss in four-square material is much lower, which is advantageous in some engineering applications. The ratio of rotational loss to alternating loss at 50 c/s in four-square silicon iron is about 2:1 over a wide range of flux densities, and is about the same as found in previous work on single crystals of silicon iron measured under slowly changing (static) flux conditions. Although the alternating power loss of hot-rolled silicon iron is larger than that of both four-square and Goss-oriented material, the ratio of rotational power loss to alternating power loss is again about 2:1. As is discussed, on modern domain theory such a result should be obtained whenever a material has equal properties in two directions at right angles in the surface of the sheet.