Calculation of short circuit current of three phase transformer using equivalent circuit scheme

U ovome završnome radu je matematički obrađena prijelazna pojava prilikom nastanka kratkog spoja i izveden izraz za struju kratkog spoja prema potpunoj jednofaznoj nadomjesnoj shemi transformatora. Vrijednosti tih struja su nam vrlo bitne u elektroenergetskom sustavu zbog toga što prema njima dimenzioniramo ostale uređaje u elektroenergetskom sustavu. U ovome radu su napravljeni proračuni struja kratkog spoja za transformator nazivne snage 250 kVA, i to za različite trenutke nastanka kratkog spoja u odnosu na početak sinusoide napona. Dobiveni rezultati su analizirani i prikazani u pripadajućim tablicama i grafovima, te uspoređeni s vrijednostima struja koje se dobiju prema pojednostavljenoj nadomjesnoj shemi.This final thesis analyzes the transient phenomena which occurs during a short-circuit and the derived expression for short-circuit electric current according to the complete one-phase equivalent transformer scheme. The values of these electric currents are very significant in the electromagnetic system because other devices in the electroenergetic system are dimensioned according to them. This thesis shows calculations of short-circuit electric currents for a transformer with a rated output of 250 kVA, for various short-circuit occurrences in relation to the beginning of the voltage sinusoid. The achieved results are analyzed and displayed in their related tables and graphs, and they are compared to electric current values which are attained according to the simplified equivalent scheme