Inception of corona and rate of rise of voltage in diverging electric fields

Abstract

Semi-empirical relationships are given for corona inception fields in air, under both steady and impulse voltage conditions. These have been related to inception voltages and, in the impulse case, to the rate of rise of voltage. Experiments with impulse voltages of varying dV/dt, applied to hemispherically ended rods of three different radii, show agreement with theory. It is shown that the expressions derived provide a useful tool for the quick calculation of positive corona onset.