INVESTIGATION OF SURFACE SCRATCHED SILICON STEELS IN 3-PHASE STACKED MODEL TRANSFORMER CORES

Commercial domain refinement of high permeability grain oriented 3% silicon iron reduces the losses when the material is magnetised along its rolling direction but it can be harmful in some regions of transformer joints. A model 3-phase transformer core was assembled from a set of laminations firstly non-scribed, then partially scribed and finally in a fully scribed condition. Mechanical scribing reduced losses in the partially treated and fully treated cores by 7.6 and 5.6% on average over the range from 1.5 to 1.8 T. The improvements are due to reduced comer losses and improved flux uniformity in the core.