Comparative study of AC and DC breakdown voltages in Jatropha methyl ester oil, mineral oil, and their mixtures

This paper is aimed at the comparison of breakdown voltage (BDV) of oil mixtures consisting of Jatropha curcas methyl ester oil (JMEO) extracted from the fruit seeds of jatropha curcas plants, and mineral oil (MO) under AC and DC voltages. Two JMEO/MO oil mixtures were considered: (50% JMEO + 50% MO) and (80% JMEO + 20% MO). The goal was to predict the insulation behavior of power transformers when re-filling with JMEO after they were emptied of mineral oil. The statistical analyses of the experimental data shows that the BDV values conform to normal law. It is shown that the (80%JMEO+20%MO) oil mixture is the most interesting whether under DC or AC as it shows the highest breakdown voltage. The U1% of JMEO under AC voltage is higher than those of the other tested oils. And the U1% of oils mixture (50%JMEO+50%MO) is the lowest one.