高压电缆缓冲层轴向沿面烧蚀故障机理分析

为了研究运行电压下电缆缓冲层轴向沿面烧蚀故障机理,建立了高压电缆轴向沿面烧蚀数学模型,根据110 kV交联聚乙烯(XLPE)绝缘电力电缆结构及实际尺寸,计算了电缆发生放电现象时电缆金属护套与绝缘外屏蔽的脱离距离,分析了高压电缆轴向沿面烧蚀的影响因素。结果表明:金属护套与电缆绝缘外屏蔽脱离是引起电缆缓冲层及绝缘屏蔽层烧蚀的主要原因。缓冲层电阻率对脱离距离影响显著,降低缓冲层电阻率可增加允许脱离距离,当电阻率达到105Ω·mm以下时,允许的脱离距离达1186 mm,不易发生轴向沿面放电。此外,允许纵向电压及缓冲层结构尺寸也是控制缓冲层缺陷的特征参数。

Analysis of axial ablation failure mechanism of buffer layer of high voltage power cable

In order to study the mechanism of axial ablation failure of cable buffer layer under operating voltage,a mathematical model of axial ablation of high voltage cables is established.According to the structure and actual size of 110 kV XLPE cable,the requirement for the separation length of the metal sheath and the outer insulation shield is calculated,and the influencing factors of the axial ablation along the surface of the high voltage cable are analyzed.The results show that the main reason for the ablation of cable buffer layer and insulation shield layer is the separation of metal sheath and cable insulation shield,and the buffer layer resistivity has a significant effect on the detachment length.Reducing the buffer layer resistivity can increase the allowable detachment length.When the resistivity is 105Ω·mm,the allowable detachment length is 1186 mm.In addition,the allowable voltage of the buffer layer and the structure size of the buffer layer are also the characteristic parameters to control the fault of the buffer layer.