The assessment of the influence of temperature of selected parameters of the approximation method of depolarization current analysis of paper–oil insulation

The paper presents the results of experimental investigations of paper–oil insulation samples from the point of view of the assessment of the influence of temperature on the parameters of the approximation method of the time characteristics analysis of depolarization current. Three types of equations: Debye’s function with a single relaxation time, Curie–von Schweidler’s function with triple Debye’s function (taking into account short, average and long relaxation times of paper–oil insulation), and Jonscher’s function with Debye’s function with a single relaxation time were selected as approximation functions, as recommended by literature. The investigated insulation samples were diversified with respect to the degree of dampness and aging. Summing up, the paper focuses on verification of the determined parameters of approximation equations in relation to the influence of insulation temperature and presents recommendations for their application in diagnostics carried out by the PDC (Polarization and Depolarization Current) Method.