Electrical treeing studies on the Araldite LY/HY 5052 epoxy resin over a wide range of stressing voltage

Electrical treeing breakdown (a long-term electrical deterioration process) has been investigated in Araldite LY/HY 5052 epoxy resin pin-plane specimens subjected to a wide range of 50 Hz alternating current electrical stress. The full process of electrical tree initiation and growth was recorded periodically by using a digital camera. The electrical tree growth structural characteristics were examined by means of the measurement of the fractal dimension. The voltage dependence of electrical tree growth time to breakdown was related to the voltage-dependent changes in the fractal dimension of the tree structures. The experimental results obtained in this study are described in terms of a quantitative physical model of electrical tree growth that has been previously proposed by the authors.