Research on Oil Pressure Rise and Fluctuation Due to Arcing Faults Inside Transformers

Oil-immersed transformer internal pressure rise and subsequent rupture due to arcing faults have received considerable attention for several decades. However, because of the difficulties, explosion risks and measurement constraints of on-site fault tests, a full understanding of the associated complex phenomena remains elusive. In this study, internal arcing faults were conducted in two full-scale 315 kVA/35 kV and 40 MVA/110 kV transformers. The experimental findings confirmed that bubble growth follows a special pulsation process with increasing arc energy. The interaction between the oil pressure fluctuation and the bubble pulsation was also identified and analyzed. Furthermore, an arc-induced gas bubble dynamics model within a finite domain is proposed. Meanwhile, a bubble-fluid-solid coupling model and corresponding detailed calculation method are developed to simulate the effects of faults in transformers. With the numerical approach, simulation results for the oil pressure fluctuation and tank deformation throughout the arc duration are obtained. Direct comparisons between experiments and simulations in various cases verify the correctness of the developed method.