Tracking and Treeing Phenomena

Research on tracking and treeing phenomena in Japan up to the present are summarized in this paper. Research activity on tracking phenomena was promoted by the Investigation Committe on Tracking Resistance Test Method of Insulating Materials organized in 1963. Various test methods such as IEC Publ. 112, IEC Publ. 587 and Merry-Go-Round have been investigated. The characteristics of scintillation generated on an insulation surface have been defined from the measurement of light pulses. On the other hand, research on treeing phenomena in insulating mate2ials was actively carried out by the Study Committee on Treeing in Insulating Materials organized in 1967. The research on treeing is divided over the four phenomena. At first, electrical t-rees have been mainly discussed. In 1971, water treeing became a serious problem, and discussion focused on its fundamental phenomena and possible mechanisms. After that, space charge effects have been studied.