Some aspects of transformer core loss

The question of total and local measurement of loss in transformer core iron, on load and open circuit, is discussed. Local loss measurement methods are reviewed and one used to find loss levels due to flux normal to the laminations. A mechanism for the generation of such flux is hypothesised and experimental evidence of its existence is presented. Experimental results are given for a test butt-lap joint in which gap and overlap were varied. The possibility of direct measurement of core loss under loaded conditions is discussed and a test method is described.