Breakdown of a thin dielectric liquid layer

Measurements of electrical breakdown on thin (10-100- mu m) liquid dielectric (capacitor impregnant) layers for different interfacial situations are discussed. For this purpose a new uniform field electrode arrangement that represents interfacial conditions close to those of industrial practice was developed. It was investigated experimentally how the dielectric strength depends on such factors as electrode area, gap spacing, nature of the interface in contact with the liquid, and temperature. The breakdown phenomena are shown to be either related to high-field conduction (i.e., boiling or electrohydrodynamic cavitation leading to the generation of a vapor bubble in the prebreakdown regime) or related to the presence of particles or to local field enhancements.<
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