Breakdown voltage characteristic of biodegradable oil under various gap of quasi-uniform electrode configuration

Petroleum-based mineral oil has been used as insulator in high voltage transformer for more than a century. However, due to the environmental issue and since the petroleum-based mineral oil is going to run out, many researchers nowadays have done a research to replace the mineral oil with vegetables oil. RBDPO (Refined, Bleached and Deodorized Palm Oil), Soybean Oil, FR3 and RBDP Olein are examples of vegetable oils that able to replace mineral oil. Since there are no reports on the breakdown characteristic at various gaps of vegetable oils, the study on the characteristic is essential. It is important for the guideline and to gain knowledge of the electrical properties of the vegetable oils for high voltage transformer application. Thus, in this study, the breakdown voltage of mineral and vegetable oils are investigated at various gap distances. The effect of various gap lengths of electrodes to the dielectric strength in different type of vegetable oil is studied. Furthermore, the constant and the exponential factor of breakdown voltage in each type of vegetable oil are also determined. The electrode shape used in this experiment is semi spherical shape and gap distance is varied from 0.5mm to 3.5mm. The result revealed that the breakdown voltage of RBDPO is slightly lower than FR3 as the gap of the electrodes increases. The transformer oil has relatively high breakdown voltage compare with other vegetable oil.