Preliminary study of bubble formation in vegetable oil filled power transformer

This paper presents the work performed to date on investigating water bubble formation in transformer oil and cellulose insulation systems, and any impact that using a vegetable oil dielectric will have in contrast to standard mineral oil. It is important to understand this phenomenon because it can lead to the failure of a transformer on overload, when water suddenly migrates from the cellulose into the oil. The system used to investigate bubbling is presented in this paper along with a discussion on how bubbling occurs. The next step will be to re-perform this investigation using vegetable oil under a variety of different conditions.