复合绝缘子导通性缺陷对带电作业安全距离影响

长期运行的复合绝缘子容易出现老化、破损及芯棒碳化等缺陷，对其附近开展带电作业造成安全隐患。以500 kV 线路I串复合绝缘子为例，通过开展复合绝缘子不同导通性缺陷条件下间隙操作冲击放电试验，获得了相应工况下的放电特性，并结合带电作业绝缘配合方法，确定了500 kV 输电线路I型复合绝缘子导通性缺陷的位置及尺寸限制要求。试验研究结果表明，复合绝缘子导通性缺陷存在于高压端位置时，带电作业间隙的操作冲击放电电压更低，对带电作业的安全影响更大；为保证带电作业安全开展，当复合绝缘子高压端存在导通性缺陷时，绝缘子高压端允许最大导通性缺陷长度为0.7 m；当复合绝缘子中部存在导通性缺陷时，缺陷位于距离高压端约1/4串长处放电电压最低，允许绝缘子最大导通性缺陷长度为0.9 m。确定的复合绝缘子导通性缺陷位置及尺寸限制要求，可为输电线路复合绝缘子开展带电安全检修作业提供技术支撑，可指导带电作业前复合绝缘子的安全性检测工作。

Influence of Conductivity Defects of Composite Insulators on Live-Line Working Approach Distance

The composite insulators are likely to have such defects as aging, damage and mandrel carbonization after a long-term operation, which could cause safety problem for its' live-line maintenance. In this paper, taking the I-series composite insulators of a 500 kV transmission line as an example, the discharge characteristics of the composite insulators under different conductivity defects are obtained through impulse discharge tests, and the location and size limitation requirements of the conductivity defects are determined through the insulation coordination method of live-line working. The testing results show that when the conductivity defect exists at the high-voltage end, the impulse discharge voltage of the gap is lower, which has a greater impact on the safety of live-line working; In order to ensure the safety of live-line working, when the conductivity defect exists at the high-voltage end of composite insulator, the maximum allowable length of conductivity defect is 0.7 m; when the conductivity defect exists in the middle of composite insulator, the discharge voltage is the lowest when defect exists at the position about 1/4 of the length of the insulator away from the high-voltage end, and the maximum allowable length of conductivity defect is 0.9 m. The location and size limitation requirements of the conductivity defects of composite insulators determined in this paper can provide a technical support for the safety of live-line overhaul working of composite insulators on transmission lines and guide the safety detection of composite insulators before live-line working.