高压电缆中间接头外半导电层缺陷放电研究

为研究高压电缆中间接头在外半导电层被划伤后的放电行为,采用脉冲电流法与高频电流耦合法以及硬件实时放电谱图采集,提取外半导电层含有贯穿性缺陷的高压电缆预制式中间接头中的局部放电信号,结合电场仿真以及接头放电模型对放电发展机理进行分析,结果表明:高频电流耦合传感器的灵敏度以及信噪比不及脉冲电流法,不易发现贯穿性缺陷激发的放电信号;外半导电层存在贯穿性缺陷的情况下,一旦线路中由于操作过电压或故障引起的过电压激发接头缺陷内发生放电,放电将迅速向增强绝缘层内部发展,最终形成贯穿性放电通道导致增强绝缘失效,因此实际生产安装过程中应注意防护此类缺陷,确保接头安全运行。

Discharge in High Voltage Cable Joint with Defect on Outer Semi-conductive Layer

By using pulse current method,high frequency current transformer(HFCT) and hard ware real time data acquisition technologies,partial discharge induced by perforative defect in outer semi-conductive layer of prefabricated cable joint was detected,and the discharge mechanism was investigated in the respect of electric field distribution and the discharge model to acknowledge the discharge characteristics of cable joint with scratch on the outer semi-conductive layer.The results show that the sensitivity and signal to noise ratio of the high frequency current coupling method is lower than that of the pulse current method,thus HFCT would miss the discharge signal induced by the perforative defect.The switching and fault overvoltage may induce discharge in the defect of cable joint with scratch on the outer semi-conductive layer and the discharge will rapidly expand to the reinforced insulation and finally lead to the occurrence of a perforative discharge channel in reinforced insulation.Therefore,this kind of defect should be c arefully prevented in the period of manufacture and installation to ensure safe operation of cable joint.