Statistical evaluation of the AC breakdown voltages of vegetable oil exposed to direct sunlight

This paper presents the results of the AC breakdown voltage test for the two types of vegetable oil – coconut and soybean oil, stored under dark conditions and direct sunlight for 6 months. Statistical techniques - Normal and Weibull distribution, were used to determine the AC breakdown voltage at 1, 10, and 50% failure probabilities from at least 60 breakdown measurements. It is shown that not only the average AC breakdown voltage in RBD coconut oil was, about 11% (or 15%), greater than the soybean oil (or virgin coconut oil) but its lowest AC breakdown voltage was considerably (or slightly) better than the virgin coconut oil (or soybean oil). Further, the oil storage for 6 months in dark at ambient conditions marginally influences their AC withstand voltages while the sunlight exposure considerably decreases the withstand voltage of only soybean oil with almost no change in AC withstand voltage of coconut oil. [Display omitted] •Effect of direct sunlight on the AC breakdown strength of vegetable oils are studied.•AC breakdown voltages are statistically analyzed using Normal and Weibull distributions.•Under fresh conditions, AC withstand voltages of RBD coconut oil ≅ soybean oil ≫ virgin coconut oil.•While dark storage has small influence, sunlight reduces the AC withstand voltage of only soybean oil.