Calculating leakage inductances of pancake windings in dry-type Traction transformers

Calculating leakage inductances between windings of multi-winding Traction transformers is one of the most important schemes in design procedure. In this paper, analytical and finite element methods (FEM) have been introduced for electromagnetic modeling of traction transformers with four pancake split windings. Using these models, the leakage inductances between the split windings are calculated and the models have been validated with the help of experimental data gathered from a typical 4000 kVA cast-resin dry-type transformer. Some reformations are employed to improve the FEM results and effects of these reformations on accuracy of the model are studied. Employing the validated models, the effects of middle yoke on the leakage inductances of split winding traction transformers are discussed in this paper.