Assessment of Tensile Strength of Natural Ester Oil with Comparison of Oven-Dried Bottle Method and Aging Test Chamber

This study investigates the aging characteristics of natural ester oils as a sustainable alternative to mineral oil for transformer insulation. Specifically, the research compares the performance of two types of natural ester oil with type FR3 under accelerated aging conditions. The oils were subjected to two aging methods: an oven-drying method at <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$150^{\mathrm{o}}\mathrm{C}$</tex> for 30 days and an aging test chamber designed to simulate realistic transformer operating conditions, also at <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$150^{\mathrm{o}}\mathrm{C}$</tex> for 30 days. Tensile strength was measured at specified intervals according to the IEEE C57.100 standard, and the color scale of the aged oil samples was analyzed using the ASTM D1500 method. The results indicate a more significant and faster degradation of tensile strength and color change in the aging test chamber compared to the oven-dried method, suggesting the former as a more accurate simulation of transformer aging. The findings underscore the importance of selecting appropriate aging methods in transformer insulation studies and point to potential areas for further research, such as exploring different temperatures and durations for accelerated aging tests.