高压XLPE电缆缓冲带动态导电特性与机理

高压交联聚乙烯(XLPE)电缆缓冲层烧蚀是近年来受到广泛关注的电缆故障类型。缓冲层烧蚀通常在受到挤压以及吸收水分的情况下发生，因此研究压强和吸水对于缓冲层烧蚀的影响机理具有重要意义。文中针对干燥和吸水的阻水缓冲带(简称缓冲带)在不同压强下开展模拟实验，以获得缓冲带电流密度、电压以及交流体积电阻率在烧蚀过程中的动态变化规律。同时，采用扫描电子显微镜，获得缓冲带试样的微观形貌特征。结果表明：在烧蚀过程中，干燥缓冲带试样的交流体积电阻率随时间逐渐升高，并出现短暂的电流激增和电压骤降的现象；吸水缓冲带试样的交流体积电阻率会出现随时间逐渐降低的过程，并且吸水后缓冲带试样的交流体积电阻率相比干燥时有所下降；当压强从1.09 kPa增加至5.45 kPa时，干燥与吸水缓冲带试样的交流体积电阻率均逐渐降低。结合缓冲带烧蚀模拟实验结果以及微观形貌特征可得出压强和吸水对缓冲带动态导电特性的影响机理。

Dynamic conductive property and mechanism of buffer tape in HV XLPE cables

Ablation of the buffer layer in high voltage cross-linked polyethylene (XLPE) cables has been the attractive type of cable failure. The ablation of buffer layer commonly takes place under the pressure and moisture. Therefore,it is important to investigate the effect mechanism of pressure and moisture on the ablation of buffer layer. In this study,the simulated experiments of dry and wet water-blocking buffer tape under different pressures are carried out,whereby dynamic variations of current density,voltage and alternating current (AC) volume resistivity in the processes of ablation are obtained. The micromorphology of buffer tape specimens is obtained through the scanning electronic spectroscopy. It is shown that the AC volume resistivity of dry buffer tape samples gradually increases with time in the process of ablation,accompanied with the transient surge of current and the plunge of voltage. While the AC volume resistivity of wet buffer tape samples gradually decreases with time. Moreover,a decrease of AC volume resistivity occurs to the buffer tape samples after the water absorption. With the increase of pressure from 1.09 kPa to 5.45 kPa,a decrease of volume resistivity occurs to both the dry and wet buffer tape samples. Combined with the results of stimulated ablation experiments and the micromorphology of buffer tape,the effect mechanisms of the pressure and moisture on the conductive property of buffer tape are explained.