Influence of Nano-Al2O3 on Properties of Oil-Paper InsulationDuring Thermal Aging Process
Liao Ruijin1， He Lihua1， Lü Yandong2， Zhao Xuetong1， Yuan Yuan1
1.State Key Laboratory of Power Transmission Equipment & System Security and New TechnologyChongqing University Chongqing 400044 China 2. Alstom Grid Technology Center Co. Ltd Shanghai 201114 China
Abstract：Thermal aging property of oil-paper insulation is a key factor to affect the life of transformer. In this work, nano-Al2O3 was added to insulating paper to improve its anti-thermal aging property. The composite papers containing 2% nano-Al2O3 were selected as samples of thermal aging test for the highest breakdown strength. The composite papers and normal papers were thermally aged at the temperature of 130 ℃ for 31 d. The variation of AC breakdown strength, dielectric property, degree of polymerization and tensile strength of insulating papers with aging time were obtained. The characteristics of insulating oil including furfural content, color, acid content, water, viscosity and dissolved gas were analyzed. The results show that, comparing with normal paper, the composite paper keeps higher electrical performance and the degree of polymerization and tensile strength of composite paper decrease more slowly during the aging process. The color of oil is lighter and the viscosity changes less in the oil impregnated composite paper. It is also found that the quantity of the thermal aging product of the oil impregnated composite paper is much less. Additionally, it is considered that the hydroxy on the surface of nano-Al2O3 can effectively adsorb H2O and neutralize low molecular weight acid in the thermal aging process, which restrained the catalysis of H+ in thermal aging reaction and reduced the thermal aging of oil-paper insulation.
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2017, Vol. 32 
