Surface streamer patterns induced by a strong vertical electric field under impulse voltages

Abstract

Discharge across an insulation surface is an important factor leading to insulation failure. Better understanding of surface discharge phenomenon is beneficial to the optimal design of insulation structures. In this letter, we report surface streamer propagation characteristics induced by a strong vertical electric field under impulse voltages. Surface charge density and electric field distribution are calculated on the basis of measurement of surface potential distribution, the correctness of which is verified by dust figure after surface discharge. The current signal during surface discharge is recorded as well, which achieves excellent agreement with surface streamer patterns. The difference in surface streamer patterns between positive and negative impulse voltages application is discussed in detail. It is found that under negative impulse voltages, surface discharge shows single-current pulse and multi-current pulse modes. The formation of the latter is closely related to the accumulated surface charges, electric field distribution and the discharge energy accumulated by the first streamer. The findings in this letter are helpful to better understand surface discharge phenomenon as well as to inspire new ideas for the optimal design of insulation structures.