The Impact of Needle Electrode Curvature Radius on Space Charge Distribution Evolution: A Combined Experiment and Simulation Study

The insulation of electric power equipment inevitably generates non-uniform electric fields due to internal impurities and irregular electrodes. However, the measurement of space charge distribution under non-uniform electric fields remains insufficient. In this study, based on the previous research of space charge measurement under uneven electric fields, a comprehensive investigation on the space charge distribution in epoxy resin under the influence of varying needle electrode curvature radii was conducted. A dynamic combination of experiment and simulation was employed to measure and reconstruct the space charge distribution, and the impact of needle electrode curvature radius on space charge evolution was analyzed. The results show that the distribution of space charge has similar characteristics under different needle electrode curvature radius, and the peak value of charge density all appears inside the sample and gradually moves to the depth of the sample with time. As the curvature radius decreases, the initial electric field intensity and charge injection increase. The electric field of space charge weakens the electric field of the needle surface, especially with a smaller curvature radius, resulting in a greater decrease in the peak of space charge density over time.