Axial Channel Effect on Leakage Reactance in Split-Winding Transformer.

Transformer short-circuit impedance is one of the most important output parameters in the design process. Its value depends mainly on leakage inductance, which is different for one or both shorted output windings during short-circuit test of split-winding transformer with input windings working in parallel. In this paper, an analysis of split-winding transformer with changing axial channel between winding pairs and its effect on leakage reactance has been performed for both shorted outputs. The effect is evaluated with analytical calculations, 3D and 2D finite element method simulations on a typical 5300 kVA three-phase oil transformer. The results show that the channel can’t be neglected in short-circuit calculation and the geometry of the transformer can be simplified to 2D with minimal influence on results.