Aging Behavior of Mineral Oil, Gas-to-Liquid (GTL), and Natural Ester Liquids in Presence of Cellulosic Materials

This research aims to study the aging behavior of mineral oil, Gas-to-Liquid, and natural ester oil on oil paper insulation. Experiments were carried out on oil insulation, which contained paper insulation, namely kraft paper (TUK), kraft paper (KP), pressboard (PB). Then the oil-paper insulation was placed in a sealed glass bottle & accelerated thermal aging for 1344 hours at a temperature of 150 °C. Observation of oil behavior was carried out at 336 hours intervals during aging. The aging behavior of the oil was observed by testing the oil moisture content, total acid number, breakdown voltage, color scale, interfacial tension, flash point, and Fourier Transform Infrared (FTIR). It was found that natural ester oil had better electrical performance than mineral oil and GTL. Meanwhile, natural ester oils due to their polar nature have different trends in both moisture and acid content when compared to hydrocarbon-based oils. It can be observed there is a relationship between moisture content, acidity, and breakdown voltage in all oils. The color scale shows changes with aging of the three oils, as well as the interfacial tension. Meanwhile, flash point shows the superiority of natural ester oil and GTL has a greater value than mineral oil. FTIR shows the occurrence of transesterification in natural ester oil in the 1700-1800 cm
^-1
spectrum where in mineral oil and GTL this is not found.