PREDICTION TOOL FOR OIL DIELECTRIC PERFORMANCE USING AN ELECTRICAL CIRCUIT APPROACH FOR FRESH SYNTHETIC, NATURAL ESTER, AND MINERAL OILS UNDER AC STRESS

Breakdown voltage and streamer velocity are crucial parameters in evaluating liquid dielectrics used in power transformers. The breakdown phenomenon is a complex physical process that requires a multidisciplinary approach. This paper presents a step-by-step modelling procedure for a single-arc discharge. A point-plane electrode configuration is employed, utilizing three distinct dielectric liquids. An AC voltage is applied, increasing at a rate of 1 kV/s until the breakdown voltage is reached, replicating the experimental setup. The input data include geometric parameters, such as the distance between electrodes and the radius of curvature of the point electrode, along with oil characteristics like relative permittivity ( ), dielectric dissipation factor ( ), the electric field at the point electrode tip during streamer inception leading to breakdown, and the relative permittivity of gas within the bubble. The electric circuit-based model yields quantitative results that are consistent with experimental data. The low relative error values further validate the accuracy of the prediction tool.