The influence of mechanical factors on electrical treeing

Emphasis is placed on the growing body of evidence demonstrating the importance of mechanical factors in the initiation and growth of electrical trees in solid polymeric insulating materials. Specimens using point-plane electrode geometries in homogeneous resins, with and without barrier inserts, have been investigated. The authors draw particular attention to the importance of the adhesive bond between component parts in composite insulation and the effect that this has on the internal mechanical stress. The effects of elevated temperatures and the absorption of moisture on both the mechanical and electrical characteristics of these specimens provide additional correlations between treeing and mechanical properties.