Finite element modeling of saturation and eddy current effects in commercial variable transformers

This paper presents the methodologies and some of the results of performance modeling of variable transformers. This is done by finite element (FE) modeling and computation of 3D magnetic field distribution in commercial variable transformers used as voltage stabilizers. The results are presented in terms of the effects of core saturation and eddy currents in the top plate on magnetic field distribution in and around the transformer core. It is shown that the magnitude and distribution of this field is affected by operational regimes characterized by brush and tap positions which determine the current distribution in the winding