Charge–voltage relationship of the first impulse corona in long airgaps

This paper investigates the relationship between the charge Q i of the first impulse corona and the associated inception voltage U i for a 1 m point–plane airgap submitted to impulse voltages. Experimental studies under both polarities are reported; the Q i – U i characteristics obtained allow empirical quadratic relationships between these two quantities to be derived. A physical interpretation is proposed by considering the established characteristics of the first impulse corona. The Gauss and Ampère–Maxwell laws can be applied and the quadratic Q i – U i relationship is justified by the present model.