Breakdown characteristics of paper-ice composite insulating system in liquid nitrogen

In this paper, we have studied the AC breakdown performance of a paper-ice composite insulating system immersed in liquid nitrogen. This system could be a good candidate for cryogenic electrical insulation systems, since we can expect an improvement of breakdown strength by replacing liquid nitrogen with ice, whose breakdown strength could be higher than that of liquid nitrogen. The breakdown voltage in this paper-ice composite system was higher than that of a paper-liquid nitrogen system. Furthermore we found the existence of self-healing breakdown. These results were scarcely dependent on the kinds of insulating paper and size of electrodes. The paper-ice composite insulation system is thought to be a good candidate for electrical insulating systems at cryogenic temperature