Impulse breakdown characteristics of insulating oils and their behaviour in oil-paper composites

The authors evaluated the impulse breakdown characteristics of several commercially available insulating liquids under a highly divergent field for the purpose of characterizing and screening potential candidate insulating liquids for use in high-voltage cables. The ASTM D-3300 needle-to-sphere impulse test was used as the basis for the evaluation. In addition, it was hoped that the impulse data on the oils could be correlated with those of the corresponding oil-paper composites, thus providing an effective tool for predicting cable performance in actual service conditions. The needle-to-sphere impulse breakdown appears to show some dependence on differences in oil composition. The needle-to-sphere impulse breakdown voltage shows a significant dependence on oil viscosity and temperature