Breakdown Voltage Estimation of Hybrid Nitrogen-Barrier Insulation Gap Considering Surface Charge Effect at Different Pressures

The addition of an insulating barrier has an enhancing effect on breakdown voltages of the nitrogen-insulated gap at high gas pressures. However, the barrier surface charges distort the electric field distribution, leading to the difficulty of estimating the breakdown voltage. This study proposes a method to estimate the equivalent surface charge density under different gas pressures and analyzes the influence of equivalent surface charge on the electric field distribution. The equivalent surface charge not only reduces the electric field strength near the rod electrode, but also enhances the field strength between the barrier and the ground electrode. The effect of equivalent surface charge on the electric field is associated with the position of barrier and the gas pressure. Moreover, the accuracy of the streamer criterion for the breakdown voltage estimation is analyzed. when the influence of equivalent surface charges on the electric field is considered, the calculated breakdown voltage agrees well with the experimental result, indicating the accuracy of the proposed method. The results show that the selection of the breakdown path has a significant influence on the breakdown voltage estimation at high pressures.