Other factors contributing to the core loss performance of power and distribution transformers

This paper presents results of analytical and experimental studies that give insight into the nature and mechanism of the generation of localized losses in the core joints, losses caused by core stacking-holes, and the increase of iron loss of the core material due to slitting. These three loss components alone have been found to contribute about 3–4% to the total no-load loss of a large power transformer and as much as 10% in a small distribution transformer. The results show how the magnitude of these loss components varies with operating flux density, core material, excitation frequency, and geometrical parameters of the core.