Discharge energy/material damage and thermal considerations in a solid/liquid insulating system

The occurrence of partial discharges in an insulating system consisting of lapped uniaxially oriented polyethylene tapes impregnated with dodecylbenzene oil and their effect were studied with uniform and nonuniform field electrode arrangements. The effect of various temperatures on the breakdown stress of the insulating system was investigated for the first arrangement. A correlation between discharge energy and material damage was established for the nonuniform field arrangement. The discharge energy delivered to the test object seems to be a much more useful discharge parameter than the largest partial discharge magnitude. The influence of temperature on the breakdown stress was also studied. The present insulation system performed satisfactorily up to 70°C. It started deteriorating, however, at 90°C