Numerical calculation of short circuit electromagnetic forces on the transformer winding

Based on expressions for transient three-phase short-circuit current, the formulas for radial and axial electromagnetic forces acting on transformer windings are derived. The short-circuit forces, include three components: DC component, fundamental-frequency component, and double-frequency component. Using a 17000-kVA transformer as a model, the 2-D leakage magnetic fields and forces with various phase angles are calculated by the finite-element method. The results are compared with design formulas. Numerical calculations show that the conventional design formulas used to calculate radial force can meet engineering needs