Electromagnetic Force of Power Transformer with Different Short Circuit Current Based on FEM

Abstract

Transformer winding deformation may cause security incidents of power systems, the main reason basically derives from short-circuit impulse current and switching inrush current. In order to study the influence of different inrushing current stress on winding, the 2-D finite element method (FEM) is adopted to research the stress of high and low voltage winding in a 2 kVA transformer. It reveals that, as to the axial force, the compression force occurs in both the high and the low voltage windings with the increasing of short circuit current. However, as to the radial force, the contraction force mainly exists in the low voltage winding and the expansion force mainly exists in high voltage winding, respectively. Meanwhile, the quadratic relationship between force and current is also obtained by FE analysis. Finally, the short-circuit test of an isolated transformer in the laboratory verifies that the reactance has changed obviously after the transformer winding has been deformed by axial and radial forces.