Exposure of Overhead Conductors to Direct Lightning Strikes: Modeling of Positive Streamer Inhibition

In this paper, it has been shown that a positive upward connecting leader from an overhead conductor spans a considerable part of the lateral attractive distance of the conductor. This justifies the effort to search for means to suppress streamers/upward leaders from such conductors. A new simplified model is introduced to account for the initiation and time growth of glow corona from a cylindrical conductor above ground under linearly rising fields due to cloud charges or negative downward leaders. The model was applied to assess lightning exposure of a streamer-inhibited ground wire as well as its application to lightning protection of adjacent power conductors. The paper confirms the prospect of successful application of streamer inhibition due to space charge shielding (ultra-corona) as a means for lightning protection. Streamer inhibition by using larger conductor diameters or conductors provided with an insulating layer was also considered and the limitations of both techniques were pointed out.