This study investigates the effect of cellulose particles as contaminants in natural ester oil, specifically soybean oil. The testing was conducted by measuring the breakdown voltage of pure soybean oil (control) and soybean oil contaminated with cellulose particles at concentrations of 0.05, 0.1, and 0.2 g/L, heated at temperatures of 25°C, 30°C, and 35°C. The tests were carried out using a…