Impact of Low Molecular Weight Acids on Oil Impregnated Paper Insulation Degradation

Aging of a power transformer&rsquo
s insulation system produces carboxylic acids. These acids&mdash
acetic, formic and levulinic&mdash
are absorbed by the paper insulating material, thus accelerating the degradation of the whole insulation system. In this contribution, the effect of these acids on the aging of oil-impregnated paper insulation used in power transformer is reported. A laboratory aging experiment considering different concentrations of these three acids was performed to assess their effect on the insulation system&rsquo
s degradation. Each acid was individually mixed with virgin oil, and a mixture of acids was also blended with oil. The paper&rsquo
s degradation was assessed by the degree of polymerization (DPv). It was found that the DPv of paper aged with formic acid decreased much faster in comparison to the other acids.