Medium and high voltage XLPE cables were widely used in urban distribution network. The electric-thermal effect of the cable conductor and water in the running environment are two important factors that cause ageing of cable insulating material. In this work, accelerated electrical test (AET) and accelerated water tree test (AWTT) on 10 kV XLPE cable were carried out for 1440 h, 2880 h and 4320 h, respectively. The physicochemical and dielectric properties of both aged and unaged XLPE samples were tested. Physicochemical investigation of Fourier Transform Infrared (FTIR) spectroscopy and X-Ray Diffraction (XRD) show that higher carbonyl groups index, and lower crystallinity of the XLPE insulating materials were generated in AWTT process than that in AET process. The thermal decomposition process of the AWTT XLPE are complicated, presenting a multi-peak phenomenon in the differential thermogravimetry (DTG) curve. The insulating strength of the samples after AWTT is monotonically decreased from 23.03 kV to 21.74 kV with ageing time. The dielectric properties show that the permittivity and dielectric loss of AWTT samples increased more severely than that of AET samples, with a new dielectric relaxation peak appearing at around 100 Hz. The combination of physicochemical and dielectric results reveals that AWTT process leads to more serious degradation for XLPE insulating materials. A schematic illustration is given to elucidate the development of micro defects in XLPE during the AET and AWTT processes.

中高压交联聚乙烯电缆广泛应用于城市配电网。电缆导体的电热效应和运行环境中的水分是引起电缆绝缘材料老化的两个重要因素。在这项工作中，对 10 kV XLPE 电缆进行了加速电气试验（AET）和加速水树试验（AWTT），分别进行了 1440 小时、2880 小时和 4320 小时。测试了老化和未老化 XLPE 样品的物理化学和介电性能。傅里叶变换红外（FTIR）光谱和X射线衍射（XRD）的理化研究表明，与AET工艺相比，AWTT工艺产生的XLPE绝缘材料的羰基指数更高，结晶度更低。AWTT XLPE的热分解过程复杂，在差示热重 (DTG) 曲线中呈现多峰现象。AWTT后样品的绝缘强度随老化时间从23.03 kV单调下降到21.74 kV。介电性能表明，AWTT 样品的介电常数和介电损耗比 AET 样品的增加更严重，在 100 Hz 附近出现了新的介电弛豫峰。物理化学和介电结果的结合表明 AWTT 工艺导致 XLPE 绝缘材料更严重的降解。给出了示意图以阐明在 AET 和 AWTT 过程中 XLPE 中微缺陷的发展。74 kV，老化时间。介电性能表明，AWTT 样品的介电常数和介电损耗比 AET 样品的增加更严重，在 100 Hz 附近出现了新的介电弛豫峰。物理化学和介电结果的结合表明 AWTT 工艺导致 XLPE 绝缘材料更严重的降解。给出了示意图以阐明在 AET 和 AWTT 过程中 XLPE 中微缺陷的发展。74 kV，老化时间。介电性能表明，AWTT 样品的介电常数和介电损耗比 AET 样品的增加更严重，在 100 Hz 附近出现了新的介电弛豫峰。物理化学和介电结果的结合表明，AWTT 工艺导致 XLPE 绝缘材料更严重的降解。给出了示意图以阐明在 AET 和 AWTT 过程中 XLPE 中微缺陷的发展。物理化学和介电结果的结合表明 AWTT 工艺导致 XLPE 绝缘材料更严重的降解。给出了示意图以阐明在 AET 和 AWTT 过程中 XLPE 中微缺陷的发展。物理化学和介电结果的结合表明 AWTT 工艺导致 XLPE 绝缘材料更严重的降解。给出了示意图以阐明在 AET 和 AWTT 过程中 XLPE 中微缺陷的发展。