Prediction of electrical performance of medium voltage epoxy insulated equipment

The paper presents a theoretical model based on the 2-parameter Weibull Distribution to predict the performance of cycloaliphatic based medium voltage (< 100 kV) insulation equipment. The model combines two prominent modes of degradation, namely surface damage (tracking and erosion) and flashover. New samples and samples that were aged in service and in outdoor test sites were evaluated. The flashover model is based on evaluating surface resistance under wet conditions. The degradation model is based on evaluating the tracking and erosion resistance in the Inclined Plane (ASTM D2303) test. The predictions of the model are shown to be in good agreement with experimental results. A total of 20 insulators and instrument transformers (new and field-aged) were evaluated.