绝缘管型母线运行特性及状态评估方法

Operating Characteristics and State Evaluation Methods for Insulated Tubular Bus-bar

绝缘管型母线由于具有优异的电气性能在电力系统中使用逐年增多,但作为一种新型电气设备,国内外尚无统一的规范,导致绝缘母线市场混乱,投运后陆续出现了击穿、烧蚀、破损、进水等异常运行现象,而国内外对管母的结构工艺、电气性能、状态评估方法等均研究甚少。为此全面分析了绕包式、挤包式、浸胶式3类绝缘母线的结构与关键工艺,结合已投运母线的运行特性,对其主绝缘、外护套、中间连接件、终端、接地方式等薄弱点进行分析研究。研究结果表明:绝缘母线中间连接件与终端的电场集中与密封不严,是母线故障的主要原因;交流耐压、高频局部放电检测、红外测温、接地引下线电流检测是绝缘管型母线运行状态的有效评估方法。对交流耐压试验,应尽量在开展交流耐压的同时进行局部放电检测,且须在一较高电压下持续足够时间,使缺陷能有充分的时间发展到可检测范围,以发现运行隐患点。

Insulating tubular bus-bar has been widely used in power systems for its excellent electrical performances. However, as a new electrical device, no unified norms on its structure,technology, electrical performance, and state evaluation methods are found, leading to occurrance of a confused market and some abnormal operating phenomena, such as breakdown, ablation, breakage, and water intake. Consequently, we analyzed the structures and key processes of wrapping-type, extruding-type and casting-type insulated tubular bus-bar in detail. Analyzing the operating characteristics of insulated tubular bus-bar, we discussed the weak points, such as main insulation, outer sheath, connecting parts, termination, and grounding methods. It is shown that electric field concentration and poor sealing of the connecting parts and termination are the main reasons of bus-bar fault. The AC withstand voltage, high frequency partial discharge detection, infrared temperature measurement, and current detection on the grounding wire are recommended as effective methods in daily inspection to evaluate the condition of tubular bus-bar. As for the AC withstand voltage, the partial discharge dctcction is recommended to be carried out with AC withstand voltage, and the duration time of high voltage should be long enough to find the defects in running, since the defects need some time to develop into a detectable range.