PROJECT TITLE :

Analysis of thermally aged insulation paper in a natural ester-based dielectric fluid

ABSTRACT:

The compatibility of a newly developed ester fluid (PKOAE) with cellulose insulation paper is evaluated by performing thermal ageing of Kraft paper within the new ester fluid. Thermally accelerated ageing was performed in sealed mild steel pressure vessel containing ageing catalysts, thermally upgraded insulation paper, and dielectric fluid (mineral oil and palm kernel oil alkyl ester) at one hundred fifty°C for 28, fifty six, and 84 days. Beneath the same illumination, the color level of ester aged paper samples decreased by 33percent after 84 days of ageing as compared with the color level of aged mineral oil impregnated paper samples which decreased by 73% among the identical time. Whilst the samples of PKOAE impregnated paper exhibited approximately fivepercent reduction in tensile strength when twenty eight days of ageing, the kraft paper samples closer to copper strips were found to own a significant faster degradation rate. The tensile strength of paper samples nearer to copper plates dropped to concerning 35percent of the tensile strength of the unaged sample after ageing for twenty eight days, and the paper layers farther off from the copper plates decreased by about ten%. The mechanisms that could be responsible for the slower ageing rate of kraft paper in PKOAE fluid are discussed. The characteristic breakdown strength of PKOAE impregnated paper is on the average, forty twopercent better than mineral oil impregnated paper. The high breakdown strength of PKOAE fluid might be responsible for the upper breakdown field of ester-paper system since the applied electrical stress is shared by the oil-paper combination.