Calculation of Short-circuit Mechanical Strength for Powerformer

Abstract

Initial conditions and the time corresponding to most serious states of short-circuit was got based on the T-model of power transformer. Considering the conditions to be voltage at primary winding, short-circuit forces of windings and turns for transformer were calculated with FEM coupling magnetic field and circuit method under the 2D symmetrical model. As the turn corresponding to max forces along axial and radial direction is selected to researching object, static and dynamic finite element model is presented for single turn considering the characteristics of Powerformer. Selecting 4th strength theory, the stress distributions were calculated for static and dynamic states, respectively. The relationships between equivalent stress and precompression and spacer numbers are discussed; Displacements and its spectrums were analyzed, the law of equivalent stress via time was also done. And comparisons of equivalent stress at static and dynamic were done too.