Research on Water Treeing in Polymeric Insulating Materials

Experimental and theoretical investigations for water treeing have been performed on polymeric insulating materials subjected to ac and dc stresses. It was experimentally and theoretically presumed that no water trees are initiated in polymeric insulating materials when applying dc voltage. However, water trees have been found in polymeric insulating materials even under the influence of dc stress. To determine the effects of water trees upon a cable´s life in service is now a serious problem in the world. The status of research for water trees performed so far in Japan will be presented first, and then future work will be suggested.