Effect of Dielectric Barrier Discharge Plasma Treatment on Space Charge Characteristics of Oil-Impregnated Paper

Oil-paper insulation is the primary insulating material employed in high voltage transformers. The characteristics of space charge play a crucial role in influencing electric field distortion being a key factor affecting the performance of oil-paper insulation. In this work, the effect of dielectric barrier discharge (DBD) plasma treatment on space charge characteristics of oil-impregnated paper is investigated. Under the applied DC voltage, the charge amount in the untreated oil-impregnated paper sample gradually increases. In the plasma-treated samples, the charge amount reaches the maximum value within a few minutes and then gradually decreases. After applying voltage for 30 minutes, there is less charge accumulation in the treated sample compared to those untreated. The effect of plasma treatment is intricately related to the energy dose. As the energy supplied to the DBD load increases, the trap depth in the oil-impregnated paper decreases. Consequently, the charge accumulation in the treated sample diminishes under long-term voltage application, although the accumulated charge can reach a high value in a short time at the initial stage of voltage application.