Accelerated aging testing of three types of transformer oils in 1 phase distribution transformer

EnPAT is a less flammable bio-based transformer oil derived from palm oil developed by National Energy Technology Center (ENTEC). Compared to conventional mineral oil, EnPAT exhibits superior characteristics, including fire point above 300˚C and biodegradable. This study determines the thermal and oxidative degradation of transformer insulation oils of three transformer oils: EnPAT, imported bio bio-based transformer oil, and mineral oil. Using a 6 kVA, 20 kV/220 V transformer as a testing chamber, accelerated aging tests were performed following IEC 60076-7 (2018) standards to simulate 70% expected lifespan of transformer. The duration of testing was 34-46 days. Short-circuit heating was applied to generate hot-spot temperatures ranging between 109.97°C and 113.73°C. Insulation degradation was monitored through dissolved gas analysis (DGA), furan concentration measurements, and the degree of polymerization (DP) of the cellulose-based paper insulation. Results revealed that mineral oil suffered harsh degradation (DP <200; 2-furaldehyde >1,280 ppb), while both EnPAT and imported oil maintained DP values above 400 with furan levels between 250 and 600 ppb, indicating significantly enhanced chemical stability. The estimated degree of polymerization can be determined using 2-furaldehyde concentration with the Chendong equation. The status of degradation as evaluated by the Double Engineering Company. The results confirm that EnPAT provides insulation paper protection comparable to imported bio bio-based transformer oil, as evidenced by DP and 2- Furaldehyde analysis, while exhibiting superior performance over conventional mineral oil.