A. C. breakdown of epoxy resins by partial discharges in voids

With the increasing application of organic insulating materials in equipment for high voltages, interest in the study and assessment of the partial discharges in voids in solid insulating materials is also growing. This question is therefore investigated in many laboratories, and national as well as international technical committees have already worked out various proposals for tentative specifications. The International Electrotechnical Commission (IEC) ¹ has adopted the nomenclature "Partial Discharges" (PD) for such phenomena in its publications, whereas elsewhere very often the expression "corona," which has its origin in the gas discharges at sharp edged electrodes, is preferred.