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Purpose -The purpose of the paper is to compare losses and temperatures in power transformer tanks for different high current lead arrangements. Design/methodology/approach -3D computational tools MagNet and ThermNet based on the finite element method are used to calculate magnetic field distribution in 3D models of power transformers. Eddy current losses in conducting metal parts are induced by the stray magnetic field of transformer windings and high current leads. From loss distribution and appropriate cooling condition temperature values are calculated. Findings -From calculation results it is possible to understand advantages and disadvantages of different lead arrangements. The analysis is finalized with a short presentation of the influence of magnetic shielding height on temperature and loss values. Originality/value -Results give transformer designer clearer understanding of precautions that should be taken for avoiding high temperatures on the tank wall of a transformer.

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Purpose -The purpose of this paper is to determine the external magnetic field density of the traction transformer for EMU and to find the model for its computation. Design/methodology/approach -The magnetic flux density in the surrounding region of the traction transformer was modeled and calculated using FEM. The transformer was modeled in a way that tank, clamps and current sources were taken into account. Most frequent operating modes for the basic 50 Hz current harmonic, and most represented higher harmonic of 1,950 Hz loading current, were analyzed. Findings -Matching calculated and measured values were obtained on the finished transformer. The developed calculation has proved to be a useful tool for the stray field calculation outside this type of transformer. Calculated values of the flux density are lower then the maximum permitted values defined by the DIN VDE 0848 standard. Originality/value -This paper presents a study of calculation compared to measurement of magnetic field density outside an oil immersed transformer.