Study on aging characteristics of mineral oil/natural ester mixtures-paper insulation

Transformer is one of the most critical equipment insuring the safe operation of power grids. The aging of insulation materials (mainly parts are the insulation oil and transformer paper) decide the operational life of the transformer. This paper is aimed at improving the anti-aging properties of power transformer via using new mineral oil/natural ester mixtures. The aging characteristics of mixed insulating oil-paper insulation and mineral oil-paper insulation were provided through 264 days´ accelerated thermal aging at 110°C. The color of the oil, oil acidity, degree of polymerization (DP) of the paper and the thermal stability behavior of oil-paper insulation with different aging status were compared. Results show that the mixed insulating oil can not only restrain the oil oxidation itself, but also can restrain the aging rate of the paper immersed in the mixed insulating oil. The thermal stability of oil-paper insulation could be also improved by using the mixed insulating oil.