The Relationship Between Electrical Tree Growth and Partial Discharge Characteristics in XLPE

In this paper, an “integrated” cross-linked polyethylene (XLPE) needle-plate model is made to generate electrical tree. Changing the curvature radius of the steel needle, comparing the differences of morphology of treeing and partial discharge (PD). A set of experimental platform is built, the detection sensitivity of PD is 1pC. The experimental results show that the larger the curvature radius of the steel needle is, the greater the probability that electrical tree will develop into a bush tree, while the smaller the curvature radius is, it will develop into a branch tree. Under the voltage that generates electrical tree (VGET), the growth rate of branch tree is fast within 1 hour, breakdown time of model is about 6 hours. It is obtained that phase resolved partial discharge (PRPD) and discharge charge quantity-time (DCQ- T). For PRPD in 0-20min, in the positive half-cycle it is similar to a triangle, while in the negative half-cycle it is similar to a wing-shape. The maximum discharge quantity is about 216pC, which is reached it at about 5th minute, and then it is relatively stable. The VGET of bush electrical tree is higher, but the growth rate of bush tree is slower than that of branch tree, breakdown time of model is about 9 hours. The PRPD of bush electric tree is wing-shape in both positive and negative half cycle in 0-20min. However, the maximum discharge quantity is larger than that of branch tree, which is reached it at about 2.5th minute.