Ageing Kinetic Model and Lifetime Model of Oil-paper Insulation in Transformers

Using #25 transformer oil and ordinary kraft paper as raw materials,we simulated the actual transformer production process,in which the initial moisture contents of the oil-paper samples were set to be 1%,3%,and 5%,and were aged at 90°C,110°C,and 130°C.Moreover,we analyzed the polymerization degree of insulation paper in ageing process and cellulose degradation kinetic model in terms of DP.The main conclusions can be drawn as follows: the higher temperature and the more moisture contents are,the faster the degree of polymerization will decline,and more rapidly the oil-paper insulation will age.The insulation ageing rate is not constant but decreases with ageing time.The cellulose degradation kinetic model in terms of the DP loss accumulation is able to explain the real experimental data of cellulose ageing in mineral oil under different temperature and moisture contents.The apparent activation energy for kraft paper ageing in mineral oil is Ea=(101±15) kJ/mol.The oil-paper insulation life prediction model is thus established based on time-temperature superposition theory and DP loss accumulation kinetic model.