Effect of water distribution on breakdown properties of bamboo-ice composite system at cryogenic region

In recent years many measures are taken to reduce environmental load in various fields. We consider that bamboo fiber can be used, if combined with solidified water = "ice", as a substitute of glass fiber reinforced plastic GFRP for electrical insulating system at cryogenic region. We reported the effect of water absorption on ac breakdown of bamboo. Ac breakdown strength increases with increasing water content because vessel, which is a weak point for electrical breakdown, is filled with ice. Position and shape of breakdown path is strongly influenced by water content. We consider that electrical insulating properties of bamboo-ice composite system are closely related to structure of bamboo and water distribution. The fiber of bamboo is long and straight, therefore bamboo possesses strong anisotropy. In this paper we will report effect of field direction on ac breakdown in bamboo-ice composite system at liquid nitrogen temperature.