Inception Characteristics of Surge Corona on Line Conductors

Knowledge on the characteristics of surge corona on overhead line conductors is of great importance for studies on attenuation and distortion of lightning overvoltage surges. Impulse corona may initiate and grow in various discharge modes, namely, glow, intermittent, or stable streamer corona. Its inception characteristics can be described by statistical distributions with parameters dependent on the steepness of the electric field strength around the conductor and on the atmospheric conditions. Agreement between theory and experiment on impulse corona inception characteristics is achieved based on the critical volume theory. The impulse corona performance of line conductors may differ between laboratory and outdoor testing due to differences in the background density of negative ions. An empirical procedure yielding probability distributions for the inception characteristics of surge corona on overhead line conductors is introduced.