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Partial discharges (PDs) are a useful diagnostic in high voltage apparatus, and their measurement has been greatly improved with the application of advanced pulse height measurement equipment. The interpretation of PD signatures is important to insulation analysis in highly stressed apparatus such as power transformers, cables, and capacitors.
The electrical failure of practical oil insulated apparatus often develops as a surface flashover along the interface of a solid dielectric support and the oil. While there is substantial reported information about breakdown and streamer propagation in plain oil gaps, there is little comparable information about the surface flashover case. The studies reported here concern measured surface flashover...
Stress enhancement due to the migration of charges can be a critical factor in the design of solid insulation for high voltage DC systems. The effect of bulk currents on surface and internal charge accumulation is discussed; and equations are formulated which predict steady-state conditions in arbitrary configurations o Experimental evidence is given for the validity of this analysis in epoxy insulators.
Inorganic insulators are often necessary, especially when elevated temperatures are encountered o Ceramics generally exhibit low volume insulation strength compared to more homogeneous materials and are relatively costly, whereas glasses are typically lossy and prone to low voltage breakdown under ac. A specialty glass prepared with a very low alkali metal content has been studied as a potential bulk...
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