A statistical study on the AC breakdown voltage of corn oil and mineral oil for liquid insulation

In recent years, insulation designers have been emphasized many researches on natural ester oils to replace mineral oil because of its high biodegradability, better dielectric characteristics, more resource of availability and etc. This work aims to investigate the corn oil (CO) as alternate liquid insulation to mineral oil (MO). In order to ensure the ability of natural ester as potential replacement for liquid insulation, statistical analysis of AC breakdown strength is conducted apart from measuring the other oil properties such as density, viscosity, flash point, fire point, color, moisture content and acidity. Statistical analysis of breakdown voltage on corn oil is carried out with two parametric distributions (Normal and Weibull distribution). The probability of failure with respect to the breakdown voltage on corn oil and at risk levels of 1%, 5%, 10%, 25% and 50% probability are estimated to ensure the withstand capacity of corn oil under various stress conditions. For reference purpose, mineral oil is also investigated in this work. From the statistical investigation result, it is found that the corn oil has the suitable and better breakdown characteristics than the mineral oil. Hence the corn oil has the potential to replace traditional mineral oil in high voltage transformer.