Kinetic analysis and modelling of the ageing process for Kraft paper aged in natural ester dielectric fluid

This paper describes briefly various different degradation kinetic models of cellulose and paper insulation in the literature and presents a new cumulative degradation kinetic model for loss of tensile strength of cellulose and paper insulation. Applying this model, the predicted loss of tensile strength has been compared with accelerated ageing data of Kraft paper obtained from the publications of McShane et al. of Cooper Power System. McShane et al. conducted the ageing of Kraft paper in both mineral oil and natural ester in sealed tube at elevated temperatures. It is shown that the cumulative degradation kinetic model for loss of tensile strength of paper insulation can give an excellent description of the ageing process of Kraft paper insulation in both natural ester dielectric fluid and mineral transformer oil.