Degradation and breakdown of solid dielectric materials resulting from surface discharges in air and in insulating liquids

An effort is made to identify some of the common aspects of the behavior of PDs (partial discharges) originating in different conditions and interacting with different solid dielectrics (SDs) in media of different density. Emphasis is placed on the behavior of PDs in the SD arrangement with a view to its use as a standard model system for testing the comparative resistance of various dry and impregnated solids to PDs appearing in flat and broad slits, such as those due to delamination and other defects which occur in many kinds of insulation. Observations were made on the propagation and intensity of the discharges as well as their effect on the solid dielectric surface. Results of measurements of light output in the optical range and of magnitude of the PDs are reported, and the resulting damage patterns and the breakdown probability characteristics are described.<>