Design and Manufacture of an Arc-resistant 250 MVA, 735 kV Transformer with Reinforced Side Turrets

This paper describes the design and manufacture of a 250 MVA, 735 kV three-phase transformer equipped with reinforced side turrets capable of withstanding a 20 MJ internal arcing fault, as required by one utility’s power transformer specifications. The aim of the design is to prevent turret failures which may result in violent ejection of components, major oil leakage, nearby equipment damage, and significant personnel hazards. The use of side turrets is typically prohibited due to these risks; however, transportation constraints made 735 kV sideturrets the only feasible solution for the transformer described in this paper. Consequently, the side-turrets were structurally reinforced using an arc-resistant approach previously validated by full-scale experimentation.