The leakage magnetic fields of both windings and leads are comprehensively analyzed in a 360MVA/500kV power transformer. According to the characteristics of the fields, finite element method and boundary element method are employed to solve the three dimensional eddy current problems. The different materials of structural parts with magnetic shunt, aluminum screen and no shield are discussed. The eddy current loss and its maximum density are 133.3kW and 6.1kW/m~2 respectively. Furthermore, it is found that eventhough the loss is mainly caused by the windings, the most serious temperature rise may be produced by the leads in large transformers.
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