Influence of oil mixtures on creeping dischages over solid/liquid interface
Résumé
The present paper deals with the influence of oil mixtures based on mineral oil on the morphology and final length Lf of creeping discharges over solid/liquid interface. Two mixtures are considered: a mixture (A) consisting of mineral oil with 20% by volume of silicon oil, and a mixture (B) consisting of mineral oil with 20% by volume of synthetic ester. The solid samples are issued from bakelite, glass or polycarbonate. The experiments are achieved under impulse voltages using a pointplane electrode arrangement. It is shown mat the dielectric strength of solid/mineral oil structures is improved when mineral oil is replaced by one of these mixtures. Lf is shorter in mixture B than in mineral oil; Lf is in between with mixture A. It results in an increase of flashover voltage of the insulator when mineral oil is replaced by mixture B. Lf (U) increases quasilinearly with the voltage whatever the interface.