الفهرس 
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Abstract
This thesis is an investigation and study of the mechanism of internal discharges in micro cavities in solid dielectrics with application to power cables. The magnitude, repetition rate and energy, in micro cavities in solid dielectric samples and electrical cables were studied. The field distribution in these cavities was simulated, modeled and calculated for certain applied voltage. Alternating high voltage at power frequency at room temperature was applied to different materials. A computer program was developed using the boundary elements technique to get the theoretical analysis and their associated results.
The cavity shape, cylindrical or spherical, and its dimensions were changed. The size of the cavity was much smaller than the sample thickness. The cavities location and w.r.t electrodes were changed. The study was done on samples of low density polyethylene (LDPE), polyvinylchloride (P.V.C) and ethylene polypropylene rubber (E.P.R) because of their important industrial applications. Partial discharge (P.D.) in micro cavities in the insulation of high voltage belted type power cables drastically affects their performance mainly. The field distribution and hence the rating of these cables. P.D. deteriorates, lead to the complete failure and shorten the life time of power cables. This has an adverse effect on the reliability and maintainability of power supply. That definitely affects the production of industrial factories, which reflects on the national income.