Breakdown path control by barrier effect for improving withstand characteristics of air‐insulated gaps under alternating voltages

Abstract

A polymer barrier inserted in the interelectrode gap can significantly improve the insulation performance of air-insulated high-voltage electrical equipment. With the development of power equipment towards integration and miniaturisation, multiple barriers can be used to further increase the insulation level. This paper investigated the withstand characteristics of the air-insulated rod-rod gap with multiple barriers by changing the barrier numbers, the barrier position and the barrier insertion direction. Four control modes were set up based on the assumed breakdown paths under alternating voltages. It was found that the control modes with barriers inserted from the opposite direction had a more significant improvement effect than that from the same direction. When the horizontal barrier position was closer to the electrode and the vertical barrier position was farther to the electrode axis, the breakdown voltage was higher. The vertical barrier position was a key factor affecting the probability of breakdown path type, and the breakdown voltages along different types of breakdown paths were almost the same when the barriers were at the same position. The increase of the breakdown voltage was mainly resulted from the change of electric field distribution in the insulated gap and the extension of the breakdown path length.