Analysis and experimental verification of static tilting behaviour of CTC in transformer windings

Abstract

This paper presents a numerical model and experimental verification of the critical tilting force calculation for transformer winding conductors under static axial pressure. For the purposes of this investigation a structural finite element method model of a non-epoxy bonded continuously transposed conductor used for the construction of transformer windings was developed. The mechanical behaviour of two different transformer winding conductors under static axial pressure was simulated. The radial position of CTCs was varied according to manufacturer tolerances in order to closer correspond to the actual physical models. The displacements, stresses and strains obtained from the simulation are presented and analysed. This calculation is compared to existing analytical and empirical calculations in the IEC 60076-5:2006 and available literature. The results of these calculations were experimentally checked by pressing three physical winding models in a hydraulic press with the force corresponding to calculated critical tilting force and above. The resulting deformations of the winding conductors were photographed and compared to the results of the simulations.