中文摘要：

超高压电缆附件用硅橡胶的电树枝化严重制约了电力电缆的长期安全稳定运行。为此,采用针板电极结构,在硅橡胶试品的针尖处模拟了气泡和气隙裂纹两种缺陷,在工频电压下测量其电树枝起始电压,并通过数字显微观测系统记录电树枝形态,研究缺陷对硅橡胶电树枝起始特性的影响。结果表明,试品存在气泡缺陷时,电树枝起始电压比无缺陷时有小幅下降,起始阶段松枝状电树枝与树枝状电树枝出现的比例分别为65%和35%,与无缺陷产品相比不同电树枝形态出现的比率变化不大;而存在气隙裂纹缺陷的试品,电树枝起始电压则大幅下降,电树枝形态仅为树枝状。分析表明,硅橡胶具有优异的抗氧化性能使得缺陷中的氧对其电树枝起始特性影响较小;气隙裂纹导致的机械损伤和应力集中,是引起电树枝起始电压大幅下降的根本原因。

英文摘要：

As a novel internal insulating material, the application of silicone rubber （ SIR） in power cable accessories becomes more and more widely in recent years. However, few studies were focused on the influence of defects on the electrical tree characteristics and the damage mechanism of such insulation is still unknown. Two kinds of defects, gas void defects and gas crack defects, were manufactured to simulate the actual defects in prefabricated cable accessories. The influence of defects on the characteristics of electrical tree initiation in SIR under 50 Hz ac voltage was studied in this paper. The electrical tree initiation voltage and the shapes in SIR specimen without defects, with gas void defects and gas crack defects were measured via digital micro-imaging system. It was found that the gas void defects has little effect on the characteristic of electrical tree initiation in SIR, while the gas crack defects has great effect on the characteristic of electrical tree initiation. Compared to the specimen without defects, tree initiation voltage of specimen with gas void defects decreases slightly, but tree initiation voltage of specimen with gas crack defects decreases considerably. The kind and probability of tree initiation shape appears in specimens with gas void defects are approximately in accord- ance with the specimens without defects. However, only branch-tree appears in the specimens with gas crack defects. It is analyzed that the characteristics of electrical tree initiation is slightly affected by gas void defects can be due to the great resistance of oxidation of SIR. While the gas crack defects conduces to mechanical damage and stress concentration. This leads to the great effect on the characteristic of electrical tree initiation.