Istiqomah, Rahman Azis Prasojo, Sriyono, Oksa Prasetyawan
Paper insulation degradation is really important to study, due to its impact on the lifetime of the transformer. Several previous study has published the effects on Degree of Polymerization as well as tensile strength, there is little focus from previous published studies in quantifying and correlating paper color to its degradation. This study investigates the effects of accelerated thermal aging on transformer insulation materials, focusing on the color scale of insulating oil and the luminance of insulation paper. Two types of paper, kraft and thermally upgraded paper (TUP), were immersed in natural ester oil and mineral oil, and subjected to thermal stress at 150°C for 24, 240, 480, and 720 hours. The research highlights the comparative degradation behavior of these insulation systems, examining changes in oil color based on ASTM D-1500 standards and paper luminance derived from RGB values. Results show that natural ester oil offers superior thermal stability, slowing the degradation rate of insulation paper compared to mineral oil. TUP paper consistently demonstrates higher luminance and slower degradation than kraft paper. A strong correlation between paper luminance and tensile strength suggests that luminance can serve as a non-invasive indicator of insulation health. The motivation is to encourage the use of eco-friendly insulating fluids to extend transformer lifespan and enhance system reliability. These findings support the potential of natural ester oil as a sustainable alternative to mineral oil, reducing insulation degradation and extending transformer lifespan. © 2025 IEEE.
PLN Research Institue, Department of Transmission and Distribution, Jakarta, Indonesia; Politeknik Negeri Malang, Department of Electrical Engineering, Malang, Indonesia