| Transformer is the most critical equipment insuring the safe operation of power grids, because its serious incidents will not only damage itself, but also interrupt the electricity supply. The transformer failure caused by inner insulation problems accounts for an important part of the transformer accidents. The number of oil-immersed transformers running more than 20 years has increased rapidly since Chinese Reform and Open-up. The aging of insulation materials (mainly parts are the insulation oil and paper) decides their operational life. And for the aging, materials are vulnerable which could cause equipment fail and other accidents. It is urgent to inhibit the transformer insulation aging, extend the operational life and improve the safe operation level. Nowadays, the antioxidation research of insulation oil is only focused on the oil antioxidation itself, but not on the oil and paper. Therefore, in order to improve insulation ability, the research about antioxidation transformer oil and①paper has important academic value and practical significance.The properties of natural ester paper insulation and mineral oil paper insulation were studied through 399 days'aging experiment, which not only built the experimental and theoretical foundation of further study on mixture antioxidation oil, but also tamp the foundation of research on influence of antioxidation oil to insulation paper. Then the mixture antioxidation oil is developed. The cooperation antioxidation mechanism of the antioxidants was studied, and the physical and chemical parameters of mixture oil were measured, all of them were according to the standard. The relative permittivity of the oil and breakdown voltage were studied as well. After that, the properties of mixture oil paper insulation were studied by 264 days'aging experiment. The excellent property of the oil has been studied so that we could gain the goal of antioxidation for oil and paper. The excellent properties and mechanisms of oil have been studied. The main results of this paper are as following.After the properties of natural ester paper insulation were studied. We could find that the natural ester can restrain the aging of paper.The antioxidation oil was developed successfully. The best extraction condition was advanced. The compound antioxidants 0.3%T501+0.3%L06 was brought forward. And the cooperation mechanisms of the compound anti-oxidant were studied by molecule simulation, infrared analysis and Pressure Differetial Scanning Calorimetry (PDSC).Most parameters for the mixture antioxidation oil were studied and they were consistent with GB 2536-90, including transparence, smell, density, solidifying point, flash point, viscosity, acids and water-solubility acids;The viscosity of the antioxidation oil at 20℃～90℃was as same as mineral;And the relative permittivity at 30～106Hz was invariable and it was higher than mineral oil so that the electric field of the antioxidation oil paper insulation was more equilibrious. The break down voltage of the oil was higher than mineral oil. It can be used in transformer by these research results.Properties of antioxidation oil paper insulation were studied, including the oil colour, acids in the oil, furfural concentration in the oil, water content in the oil, viscosity, degree of polymerization (DP) of the paper, acids in the paper, water content in the paper. And the results showed that the antioxidation oil can not only restrain the oil oxidation itself, but also can restrain the aging of the paper immersed in the oil.The DP-Value of the paper immersed in the antioxidation oil is more higher than the mineral oil's. Namely, the developed transformer oil and insulation paper dissolved from this kind oil have double anti-aging ability.Mechanisms of antioxidation oil paper insulation were studied. At the molecule level, this paper showed anti-aging oil mixed has bounding water molecules ability. The esterification between the high molecule acids and cellulose was prove by infrared spectrum analysis. It can restrain the hydrolysis under the thermal stress. The esterification between the high molecule acids and cellulose, and the hydrogen bond between oxygen atom in the ester has combination antioxidation ability. We suggested that IEC should develop some standards for measuring the low molecule acids and high molecule acids.
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