Streamer Inception and Propagation for Air Insulated Rod-Plane Gaps with Barriers

High voltage device dimensioning requires the prediction of the withstand voltage for test conditions like impulse, surges and AC. There is a large need of designers to have reliable design criteria and a well-defined simulation procedure for device development, which is able to predict the withstand voltage up to 10 % for arbitrary geometry. This task must be based on an appropriate model for streamer inception and propagation being at the outset of electrical breakdown. Investigations were done on a rod-plane gap without and with a barrier varying in position and size. The barrier used was parallel to the ground electrode. The streamer is initiated around the tip of the rod and will propagate in field direction until the barrier is reached. Depending on the background and local field, the streamer will find a way around the barrier towards the ground electrode. The experimental results are compared with results from numerical simulations, where the streamer inception voltage was determined from the background field. Depending on the position and size of the barrier, the withstand voltage either showed an increase or decrease compared to the withstand voltage of the air gap without a barrier.