Long Term Thermal Performance of Palm Oil and Nano Graphene Filler in Nanofluids Application on Transformer Insulating Oil and Electrical Breakdown Voltage

Abstract

Mineral oil has been used as electrical insulation for a long time due to its availability, excellent cooling and dielectric property. However, petroleum sources are nonrenewable, and it is depleting. Vegetable insulating oil is an alternative since it is renewable, environment-friendly, biodegradable, high fire-point, and has a good electrical breakdown voltage level. These properties can make vegetable insulating oil as a replacement for mineral oil that is going to be limited in availability. Nevertheless, vegetable insulating oil have high viscosity, leading to a slow flow rate on the cooling performance. This research is to investigate the breakdown voltage of palm oil-based liquid insulators. This liquid is palm oil methyl esters-based nanofluids (NPME) that was converted from the transesterification process to reduce viscosity and mixed with graphene nanoparticles. These nanofluids were also aged by thermal aging at 100 °C for 168, 336 and 504 hours before testing for their electrical breakdown voltage. The results show that the transesterification process can reduce the viscosity of palm oil by about 6.6 times. Also, the breakdown voltage of nanofluids is higher than bare palm oil methyl ester after thermal aging for 504 hours.