The study of eddy current losses in coaxially insulated windings of power transformer

On the condition of neglecting demagnetization of eddy current, eddy current losses inside transformer windings consisting of round stranded conductors were studied with the leakage magnetic field method. In order to obtain higher precision, the formulae of calculating eddy current losses about transformer windings were modified with the A-Φ-A method while considering the demagnetization. Comparing the eddy current losses of calculating values with measurement data on a model coil, the validity of the calculating method of eddy current losses were verified while the strands are not insulated mutually. Finally, eddy current losses inside windings of a tri-phase transformer were simulated and calculated, whose windings consisted of stranded conductors. As a result, it is illustrated that insulating the conductors of transformer windings is very important, otherwise the eddy current losses of a large power transformer are so huge that applying this type of transformer is difficult.