两起中压电缆绝缘屏蔽处击穿事故分析

Analysis on the Breakdown of the Insulation Shield in Two Cases of Middle Voltage Cable

在电网规模不断扩大的今天,城市配电网电缆的长度已经逐渐超过了架空线路的长度,这就对电缆线路供电的安全性和可靠性提出了更高的要求。在电缆线路的运行过程中发现,经常会出现电缆端部金属护套和屏蔽层断开位置绝缘被击穿而引发事故的情况。简要阐述了国网晋中供电公司发生的两起中压电缆事故,并分析了电缆端部绝缘屏蔽处的电场分布情况,就如何改善电场分布,降低电缆端部金属护套和屏蔽断开后电场强度问题提出了相关意见,以期不断提升运检质量。

With the increasing size of the network, the cable length of urban distribution network has been gradually over the length of the overhead lines, which puts forward higher requirements on the safety and reliability of the cable line. In the course of the operation of the cable line, it is found that the insulation of the metal sheath and the shielding layer of the cable end are often caused by the breakdown of the insulation. This paper briefly describes the occurrence of two cases of medium voltage cable accident in State Grid Jinzhong Power Supply Company, and analyzes the electric field distribution at the end of the cable, relevant suggestions on how to improve the electric field distribution, reduce the electric field strength of the cable end metallic sheath and shield off the electric field strength are put forward, in order to continuously improve the quality of inspection.