抄録
In general, a polymer insulator applied high voltage reaches a complete breakdown through a extension of electrical trees. We showed in previous paper that metal hydroxide has a restraint effect on the growth of an electrical tree and that the lifetime of the polymer insulator can be improve. Calcium carbonate, endothermic particle, also has the property of endothermic reaction at a high temperature. Therefore, we have studied the restraint effects of the endothermic filler without hydroxyl group on treeing this time. As a result, it was confirmed that the voltage lifetime of epoxy resin with 30 phr of calcium carbonate was approximately 100 times longer than that of the neat epoxy resin. Moreover, amorphous part of calcium carbonate was detected by the electron beam diffraction analysis of the fillers located contiguous to electrical tree, and it showed that endothermic reaction of calcium carbonate was took place. The restraint effect of the tree growth by fillers was generally explained by a barrier effect, but the endothermic fillers such as calcium carbonate that generated the endothermic reaction have another mechanism for restraint of tree growth.
