Abstract: The compatibility of different hydrocarbon composition transformer oils with various rubber materials (hydrogenated nitrile rubber, fluororubber, chloroprene rubber, EPDM, and silicone rubber) was investigated using a 100 ℃, 164 h transformer oil rubber compatibility test and blank sample aging tests. The degree of influence of various rubber materials on the color, acid value, interfacial tension, dielectric loss factor, and breakdown voltage of different hydrocarbon composition transformer oils, as well as their relationship with the aromatic hydrocarbon content of the transformer oil, was analyzed. The results show that the aromatic hydrocarbon content has a significant impact on the chromaticity, acid value, and dielectric loss factor of the transformer oil; the higher the aromatic hydrocarbon content, the darker the color, higher acid value, and higher dielectric loss factor of the transformer oil after the rubber compatibility test; the impact of rubber materials on transformer oils with low aromatic hydrocarbon content (whether paraffinic or naphthenic) is not significant. Fluororubber has the best compatibility with transformer oils of various hydrocarbon compositions, followed by nitrile rubber, while EPDM, silicone rubber, and chloroprene rubber have poor compatibility with transformer oils of various hydrocarbon compositions. Rubber materials with poor compatibility have a significant impact on the interfacial tension, dielectric loss factor, and breakdown voltage of the transformer oil, with this impact extent being much greater than the influence of the hydrocarbon composition of the transformer oil.

Key words: transformer oil, hydrocarbon composition, rubber material, compatibility