Statistical study of impulse corona inception parameters on line conductors

Laboratory tests on corona on line conductors of cylindrical cross-section have provided charge measurements and surface field data for negative corona resulting from double-exponential and oscillatory impulses. The charge measurements show that minimum corona charge is injected for impulse front times intermediate between the standard lightning and switching impulse shapes. This result is associated with the interdependence of the corona charge and the statistical time lag of corona inception and with the time required to clear the corona space charge. Time lag effects are simulated by applying critical volume theory to line conductor geometry. The corona space-charge field reduction is quantified by the electric field measurements using a cylindrical field filter.