Development of deterioration assessment method for oil-filled transformer sealant by impact test

Oil leakage from an oil-filled transformer is the most typical trouble mode. A rubber sealant is used in various parts of an oil-filled transformer, and deterioration of this sealant is one of the causes of oil leakage. Authors focused on the impact test in vibration. In the impact test, a hammer is used to excite the object and the vibrations caused by the excitation are measured by an accelerometer. It was found that the deterioration of sealant appears as a change in vibration damping. In this study, we explain that the natural vibration excited by the impact test and its vibration mode could be understood by the analysis of the finite element method. We investigated the relationship between the amount of attenuation and the deterioration of the sealing material of the transformer butterfly valve in service.