In the 2011/12 year I made Diploma Thesis Design subject in cooperation with CG Electric Systems Hungary Zrt. (formerly Ganz Transelektro Zrt.). At the Transformer Division my tasks included the the study of the most important design literatures and a given technical specification. In addition, through a concrete example, designing an active part for the power transformer and present the short-circuit duties. My thesis also includes the voltage distribution in the transformer and field calculation for one of the critical part of the insulation system.
Power transformers are designed and constructed to withstand the thermal and dynamic effects of external short circuits without damage. During short circuit the currents through the windings attain values about one order of magnitude higher than the rated ones. The windings are submitted to extremely high electromagnetic forces and high temperatures produced by the fault currents. Calculation of electromagnetic forces and stresses is performed by finite element software, ability of the transformer to withstand the thermal effect of short circuit is checked in accordance with IEC 60076-5. My examined transformer has highly safe desing in respect the short circuit withstand ability.