COMPARATIVE STUDY OF ACCELERATED THERMAL AGING OF PAPER IN MINERAL OIL, NATURAL ESTER, AND GAS-TO-LIQUID

• Main Author: Daris, Ilhamid
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/58428
• Institution: Institut Teknologi Bandung

Mineral oil has been used for a long time as an insulating liquid in transformers. Mineral oil is a hydrocarbon-based oil that is difficult to decompose and is toxic. The use of this type of oil in the long term can cause environmental problems. Natural ester oil is used as an alternative because it has the advantage of being more environmentally friendly. However, the use of transformer oil made from ester oil is only often found in small or distribution transformers. This is due to the limitations of testing standards and the lack of research or studies on ester oil as transformer liquid insulation. For this reason, this study will compare several types of oil using paper degradation rate parameters in the accelerated thermal aging process. The oils compared are natural ester oil (FR3 Cargill Fluid), mineral oil (Nynas Nitro) and Gas-to-Liquid (Shel Dials S4 ZX-i). There are three types of paper used in this research, namely kraft paper, thermally upgraded kraft paper (TUK), and high-density pressboard (HPB). Each paper and copper were immersed in oil and then heated in an oven at 150 °C for 1344 hours. Prior to accelerated thermal aging, a preconditioning process is carried out so that the water content in the paper and oil is reduced. The system used is atmospheric air and observations are made every 334 hours for the duration of aging. The rate of paper degradation was observed through the Degree of Polymerization (DP) test on kraft paper and TUK, for changes in the chemical structure of the paper it would be observed through the Fourier Transform Infrared (FTIR) test. In addition, acidity and moisture tests were also carried out to see the oil-paper interaction during aging. The degradation of kraft paper and TUK polymers immersed in natural esters (FR3) was smaller than the other two oils. This indicates that natural ester oils have good thermal stability as evidenced from TGA/DTA testing and can extend the life of transformer paper. The aging rate of paper on mineral oil is almost the same as that of GTL oil because both oils are hydrocarbon based. The lower degradation rate of natural ester oil is caused by the hydrophilic nature of the oil which can absorb water from the paper, the oil aging product in the form of high molecular acid (HMA) which is not a paper aging accelerator, and the transesterification process. These three mechanisms are evidenced by the low water content of the paper immersed in ester oil, and the appearance of IR absorption in some spectra with aging. From the research, it was concluded that paper immersed in ester oil had a lower rate of degradation due to the presence of fatty acids from the transesterification process.