In power transformers with split type two secondary windings, nonsymmetrical configurations are possible. The design of these transformers considers two low voltage windings mounted one on top of the other and the regulating and high voltage windings divided in two parallels. Due to the specific design of these transformers, circulating currents can exist in parallels of the high voltage and regulating windings. These currents can affect the load losses inside the transformer as more parts of the winding are energized than in the symmetrical configuration. Moreover, they may affect the design of the winding itself since the amplitudes of these circulating currents can be significant and therefore have to be taken into account during the design phase. It is possible to calculate these currents using the finite element method (FEM) software in order to check if their values exceed the design values and to more accurately calculate the load losses of the transformers. In this paper, the results of the 3D FEM calculation of such power transformers are shown and compared with the measurement results in terms of circulating currents amplitudes in high voltage and regulation windings parallel parts. Additionally, a comparison between calculated and measured load losses is given.
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