Time-to-Flashover Characteristics of Polluted Insulation

Abstract
It is shown that times to flashover obtained by von Cron and Dorsh with alternating voltage on an artificially polluted insulator can be fitted into a relation ( V2-V02) t = KR2 where V is the applied voltage, t is the time to flashover, R is the resistance of pollution, and Vo and K are experimental constants. Experiments were carried out using pulse unidirectional voltage applied to a narrow conductive path of water solution of sodium chloride, and the empirical expression obtained was V2-V02) ≈ CR2L3 where L is the leakage length and C is another experimental constant. These relations are explained as results of an energy equation p·δt = e·δt whereδt at is the time required to extend the discharge by δx, p being the power available for the discharge Propagation and e the energy required to elongate the discharge by a unit length.

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