外护套环流及接地不良对电力电缆的影响分析

Analysis on Cable Sheath Circulating Current and Imperfect Grounding

对于电力电缆来说,由于电磁耦合的存在,当电缆长度不同时其外护层应采取单点接地、全接地(两端接地)、交叉互联接地等方式,避免由于外护套接地不当产生环流;电缆敷设应注意保护外护套,避免损坏,造成外护套多点接地产生环流。在环流回路中接触不良局部产生高温过热或由于环流过大所产生高温过热会对电缆的绝缘造成不良影响,甚至烧毁电缆绝缘。针对几条运行电缆外护套环流的实测和一条在试验中烧坏的电缆的初步分析,为运行中电缆的外护套接地方式和电缆试验提出了参考意见。

For the electromagnetic coupling of high voltage single core power cables,the outer sheath of power cables should be grounded at different mode,one point grounded ,two ends grounded and crossbonded grounded according to the length of cable,to reduce the circulating current of outer sheath.Bad laying for power cables will lead to multi points earthed for outer sheath,and overheating induced by circulating current will damage the insulation of power cable.this article give analyse to circulating current of several outer sheath of power cables in service and a cable damaged in test. some advice is given to ground mode for outer sheath of cable and cable test.