The effect of molecular structure on prebreakdown phenomena in dielectric liquids under a nonuniform field

Abstract

AbstractIn the present work, prebreakdown phenomena in dielectric liquids which have various molecular structure, especially those with chlorine or fluorine atoms and some double bonds included in their molecular formula, are observed in detail for positive and negative point polarities, under the application of an impulse voltage (1.1/225 µs) to the point electrode. As test liquids, cyclic hydrocarbon liquids such as cyclohexane, benzene, chlorocyclohexane, monochlorobenzene, hexafluorobenzene, and cyclohexene are used. Results obtained in these liquids are compared with those obtained in straight‐chain hydrocarbon liquids.As a result, the propagation of negative streamers, especially in dielectric liquids with chlorine or fluorine atoms in their molecular formula, is promoted, whereas the propagation of positive streamers in dielectric liquids with some double bonds is promoted. The former is related to a large electron affinity, the latter is due to π electrons, for both cyclic and straight‐chain hydrocarbon liquids. © 2002 Scripta Technica, Electr Eng Jpn, 139(1): 1–8, 2002; DOI 10.1002/eej.1140