Morphological Feature Analysis of Electrical Tree Growth in Epoxy Resin Under Tensile and Compressive Stress

In this article, electrical tree morphological features in epoxy resin under tensile and compressive stress are investigated. The applied tensile and compressive stress varies from 0 to 30 MPa, whose direction is perpendicular to the needle electrode. The obtained results show that the tensile stress accelerates the tree growth, especially in the direction parallel to the tensile stress. With the increasing compressive stress, both the tree length and the corresponding accumulated damage decrease first and subsequently increase. By comparing the tree distribution in parallel and vertical directions, it is found that the tree mainly propagates to the ground electrode under the compressive stress. A tree growth curve is proposed to explain the experimental results, which reveals the defect generation and the tree propagation driven by both electrical and mechanical stresses. The growth curve can predict the tree-induced dielectric breakdown in epoxy resin under mechanical stress.