Mineral Mix and Soybean Oil Methyl Ester as an Alternative to the Transformer Insulating Oil

Liquid insulation are many used in high voltage equipment, for example in power transformers. In general, the liquid insulation used in power transformers is petroleum mineral oil. The continuous use of petroleum causes problems, they are going run out in the future because non-renewable of petroleum. Another alternative is needed for insulating oil in transformers. This study aims to determine the best composition of five variations of soybean methyl ester oil mixture with mineral oil as an alternative material for transformer insulation. The measured parameters were breakdown voltage and dielectric strength at various temperatures, viscosity, flash point, and acidity. The results showed that sample B met the standard with a dielectric strength of 134.24 kV/cm, a viscosity of 9.95 cSt, a flash point of 148 °C, and an acidity of 0.03 mg KOH/g.