Treeing growth characteristics in HTV silicone rubber considering mechanical stress

To investigate the effects of mechanical stress on treeing growth characteristics in HTV silicone rubber under different pulse frequencies, electrical tree growth process was observed. The dependence of electrical tree characteristics on pulse frequency was analyzed. Moreover, the electrical tree propagation characteristics and mechanism were researched under different tensile strain and compressive strain. The results indicate that the tree initiation probability becomes higher with accelerating the propagation of the electrical tree when the tensile strain is increased. Furthermore, the accumulated damage of the treeing area is also enlarged as the tensile strain increasing, which aggravates the destruction for the insulation materials. However, when the compressive strain is increased, the tree initiation probability becomes lower with retarding the propagation of the electrical tree. The accumulated damage of the treeing area is also reduced as the compressive strain increasing, indicating the destruction for the insulation materials is restrained. The tree initiation probability is improved and the propagation of electrical tree is accelerated as pulse frequencies increasing regardless of the mechanical stress. When the sample is stressed under lower electric field, the tree channels are not instantly initiated and the tree initiation process can be distinctly divided into three stages; while the single tree channel is immediately generated after the higher electric field is applied on the samples. In the paper, the relationship between the electrical tree and mechanical stress is established, which provides a reference for the stress control analysis of the cable accessories. © 2016 Chin. Soc. for Elec. Eng.