Abstract
High-field electrical breakdown of solid dielectrics is of particular interest to the electricity generation and transmission industries, where the life expectancy of insulation is often uncertain. In order to study and explain the phenomenon a collaborative project has been set up involving National Power, National Grid, King's College London, City of London Polytechnic, Manchester University, Glasgow College of Technology and Bristol University. This paper further develops a time-dependent model of charge injection into a solid dielectric. It explores the quantum mechanics-based theory of how charge crosses from the metal injecting electrode into the dielectric. A current-field relationship is derived, several approximate forms quoted and their limitations discussed. Particular reference is made to an experimental situation for which a curve of injected current versus field is calculated numerically. This is applied to a model of dielectric charge transport and charge distributions are simulated for two experimental geometries.
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