| Oil-paper insulation which has decisive effects on the limiting capacity and operation reliability of transformer is an important part in transformers. With the development of EHV/UHV, the traditional mineral oil-paper insulation can't satisfy fire resistance requires and it also causes environmental pollution. In the situations of petroleum exhaustion, insulating vegetable oil will be the green substitute as mineral oil. As a new environmental friendly dielectric liquid, insulating vegetable oil is renewable and has a higher fire point. Meanwhile it has excellent electric properties. The dielectric constant of insulating vegetable oil is about 1.5 times larger than that of mineral oil, which is helpful to improve an uneven distribution of electrical field in oil-paper insulation. Based on referring to lots of domestic and overseas literatures, the refining process, the physical & chemical properties, electrical properties of insulating rapeseed oil, the moisture diffusion and impregnation characteristics in rapeseed oil-paper insulation are studied in this paper. The primary content of my dissertation is shown below:â‘ According to the main fatty acid of insulating vegetable oil, the crude vegetable oil for insulating liquid is chosen. Based on the current refining technology of oil, the refining process of insulating rapeseed oil is optimized. The primary physical & chemical properties and electrical properties of insulating rapeseed oil are tested in reference of correlated test standards of insulating oils. Meanwhile, the contrastive analysis is made with as the insulating mineral oil.â‘¡On basis of one-dimensional model of Fick's second law, a partial differential equation is designed to analyze the moisture diffusing characteristics in rapeseed oil-paper insulation. An experimental system and method for the moisture diffusing characteristics in rapeseed oil-paper insulation are set up, and the moisture diffusivity is fitted according to experimental results. By analyzing the boundary condition and solving the equation, the formula for calculating moisture concentration is obtained and moisture concentration dynamic distribution curves of oil-paper insulation are simulated. Meanwhile, the contrastive analysis is made with as the mineral oil-paper insulation.â‘¢Based on the impregnation mechanism of oil-paper insulation, the main influencing factors during the impregnation process are discussed. An experimental model for the impregnation in rapeseed oil-paper insulation is designed. The impregnation length verse times curves are obtained according to the experiment. Meanwhile, the contrastive analysis is made with as the mineral oil-paper insulation and theoretical values...
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