Determining Specific Power Loss in Joint Area of Laminated Magnetic Core

This paper discusses the method of analysis of specific power loss in the joint area of steel laminated core. The method is based on comparison of power loss data obtained from the tests of a circular shape magnetic core. Initially, the core build using uncut (solid) lamination sheets was tested to obtain the loss reference values. Then the laminations were cut onto four sections, and the core was tested again to obtain the loss increase associated with the implemented joint area. The test readings were processed to separate losses due to tangential and normal fluxes in the laminates. The processed data represented as relative p.u. values of increase in specific power loss have been extended to conduct an analysis of a rectangular magnetic core made using anisotropic, grain-oriented silicon electrical steel. The results demonstrated that the power loss produced by the normal magnetic flux dominates in the structure of total power loss in the rectangular core (approx. 85%). The proposed approach utilises the septation of losses produced by tangential and normal fluxes; it can be applied for the analysis of loss in the joint areas of magnetic cores of various power transformers.