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

Abstract

This paper investigates the relationship between the charge Qi of the first impulse corona and the associated inception voltage Ui for a 1 m point–plane airgap submitted to impulse voltages. Experimental studies under both polarities are reported; the Qi–Ui 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 Qi–Ui relationship is justified by the present model.