The Influence of Organic Acid on Thermal Aging of Power Transformer Oil-paper Insulation

To research the influence of one of the aging product (organic acid) of cellulose on oil-paper insulation, low molecular weight of the carboxylic acid (formic, acetic) and high molecular weight of the carboxylic acid (stearic) have been added to new electric insulating oil to arrive at a neutralization value of 0.3mgKOH/g, the initial moisture content in insulation paper have been controlled at 0.5% and 2.75%. The distribution characters of organic acid in oil-paper insulation and the influence of organic acid on thermal aging of oil-paper insulation at 70°C, 90°C and 110°C have been investigated. Experimental results show that formic and acetic could be easily absorbed by insulation paper while stearic could easily dissolve in electric insulating oil. There is no significant influence of temperature and initial moisture content on the distribution characters of organic acid in oil-paper insulation. Low molecular acid would work together with moisture to accelerate the aging speed of insulation paper.