Short-circuit withstand capability of power transformers - Part I

This article discusses verification of the ability of a transformer to survive short circuit. Fault current leads to large axial and radial forces on windings, which have to be managed by proper structural design. Test experience, showing a failure rate of 20-25 % of well-prepared transformers, suggests that the highest degree of reliability with respect to short-circuit withstand verification is ensured through full-scale testing in accordance with the international standards. The prime failure mode is winding deformation, but many other deficiencies, which would not be discovered in a design review, have also been observed. Since 2016, KEMA Laboratories is equipped to short-circuit test transformers up to the 800 kV class