Influence of the Relative Amount of Paper on Aged Mineral Oil Decay Products

Aging of different oil-pressboard insulation ratios was investigated under controlled laboratory conditions. Modern diagnostic tools and techniques were used to assess the degree of influence of the relative amount of cellulosic materials on aged mineral oil decay products. Determination of relative content of dissolved decay products by spectrophotometry, solid suspension by turbidimetry, Fourier transform infrared spectroscopy, and electrical diagnostic techniques were used to judge the most affected oil parameters by oil/pressboard proportion and thus the most effective way to choose the best proportion that can reduce solid insulation degradation and increase power transformers lifespan. A quantitative study of the effect caused by the ratio of oil and paper can help to a better modeling of solid insulation end of life.