Study on Physicochemical Properties of Liquid Crystal Based Natural Ester Insulation Oil

Natural ester insulation oil is gradually becoming a n ideal substitute for mineral oil due to its high ignition point and environmentally friendly properties. However, natural ester insu lation oil has inherent problems such as a high pour point, and it is difficult for traditional additives to improve the pour point and flash point simultaneously. To further improve the performance of natural ester insulation oil, we used soybean oil as the matrix a nd selected 4-[difluoro(3,4,5-trifluorophenoxy)methyl]-4’-ethyl-3, 5-difluorobiphenyl, a compatible nematic liquid crystal, as functi onal additives. The physicochemical performance tests showed th at the breakdown voltage, flash point, and pour point of the liqui d crystal based insulating oil were improved to different degrees i n the concentration range. Especially, the liquid crystal mass fraction of 0.5% produced the most significant modification effect. Th e study further validates the synergistic optimization of two relati vely contradictory indexes, which is of great significance for bala ncing the low-temperature performance and flame retardancy of the insulation oil.