Rise-of-temperature method for building factor distribution in 1-phase model transformer core interior considering high DC bias

Abstract

Loss distributions of transformer cores are affected by z-flux effects if considered for the core surface. Here we propose the application of a thermal sensor which is inserted to the core interior through one of 16 channels of 2 mm width. Measurements were made on a 1-phase core assembled from laser-scribed SiFe. Throughout the core, the local building factor BF proved to increase towards the periphery which can be interpreted by interactions of highest anisotropy and non-linearity. Additional DC superposition yields non-uniform increases of BF at different core positions. Local losses tend to become more balanced – measurement locations with a priori high BF experience lower percentage increases, being more robust with respect to DC components.