This paper investigates the relationship between the charge Qi of the first
impulse corona and the associated inception voltage Ui for a 1m
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 Amp`ere–Maxwell
laws can be applied and the quadratic Qi–Ui relationship is justified by the
present model.
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