Design and Testing of an Arc Resistant Power Transformer Tank

This paper presents the design and testing of a full-scale 330-kV, 210-MVA transformer tank designed to withstand the pressure effects of a 20 MJ, three-cycle low-impedance fault in oil, and fail at its cover in a safe and controlled manner above that amount of energy. The transformer tank, equipped with a mockup active part, was designed for arc resistance using nonlinear static finite-element analysis and a specific rupture criterion. It was then tested using an experimental methodology based on injecting pressurized air into the water-filled tank. To adequately reproduce the effects of an arc in oil, the test parameters were determined using explicit dynamic simulations. The transformer tank performed as predicted by the finite-element and explicit dynamic simulations. The energy levels used in the tests here are, to our knowledge, the largest ever reported. This study demonstrates that it is feasible to design a power transformer to safely withstand high-energy low-impedance faults of short duration.