Investigation of the role of void sizes for failure of high voltage bushing

This paper presents the investigation of the root causes of the high voltage bushing failure in a Power Station which occurred on July 12, 2015 in Brunei Darussalam. Upon physically examining the burning parts of the bushing, a computer simulation was carried out to analyze the contribution of void sizes towards the failure of bushing. COMSOL Multiphysics software was used for the analysis. For simulation, an actual diagram of the high voltage bushing was drawn using the Autodesk Inventor. Different scenarios with the presence of 1 mm and 1.5 mm diameter void sizes were considered in the XLPE insulation part of the high voltage bushing. Considering different depths of 1 mm, 5 mm and 11 mm, respectively, simulation results were obtained for void sizes with full, 50% less and without oil insulations. The simulation results showed that the bushing failure occurred due to oil leakage and different sizes of voids. It was also summarized that the physical inspection could help in predicting and preventing high voltage bushing failure in the future.