Flux distribution in five-limb transformer cores

Abstract The flux distribution in 3 phase, 5 limb, power transformer cores has been computed using a finite element technique in two geometries with two types of material. In the one geometry the limb laminations were split as is common practice in large transformers and in the other geometry the full width limb laminations were considered. Grain-oriented and non-oriented cores were modelled. Higher flux distortion and less uniform flux distribution were found in the split cores due to the changed path reluctances, which in practice would lead to higher losses in such designs. Also higher flux distortion occured using grain-oriented steel with the split geometry than when using non-oriented steel, indicating that a poorer building factor would generally be obtained when using highly oriented steel.