Interference of Stray Gases in the Diagnosis of Low-temperature Faults in Soybean-Based Natural Esters

In this work, the interference of stray gases in the diagnosis of low-temperature faults in soybean-based natural esters (SBNE) is analyzed. For this purpose, two vessels with windings are used which heat SBNE at $80 ^{\circ}\mathrm{C}$ for 69 days, where one of them has a $200 ^{\circ}\mathrm{C}$ hot spot. Samples are taken at 12, 25, 39, 54 and 69 days and gas concentrations, increments, relative proportions and DGA interpretation criteria are analyzed. The results obtained show that the relative gas patterns are similar for both models. The DGA diagnostic criteria have difficulties distinguishing between fault-free and faulty conditions. The use of absolute concentrations and gas rates seems to be the best option to differentiate both cases.