Polymeric nanocomposite insulations are receiving the widespread attention of the electrical cable industry. This paper presents the electrical insulation performance of as‐received commercial 320 kV high‐voltage direct‐current (HVDC) cross‐linked polyethylene (XLPE)/MgO nanocomposite material with reference to the pure XLPE. The results of this commercial‐grade electrical insulation material are not reported hitherto. The scanning electron microscopy confirms the well‐dispersed nanofiller inside the polymer matrix. The DC electrical insulation performance is investigated by DC breakdown strength, space charge, DC electrical conductivity, and surface potential decay measurements. The test samples are subjected to the thermal aging at 135°C for 30 days. The un‐aged nanocomposite exhibits 20% higher DC breakdown strength, negligible hetero space charge accumulation, and the lower DC conductivity by one order than the un‐aged pure XLPE. Moreover, thermally aged nanocomposite shows more restraint to the deterioration of its properties. After the thermal aging, the DC breakdown strength decreased by 38% and 20% in the pure XLPE and its nanocomposite, respectively. Thermally aged nanocomposite shows negligible hetero charges and an increase in the DC conductivity by one order. However, the pure XLPE shows higher hetero charge accumulation and the increased DC conductivity by one order. In un‐aged XLPE nanocomposite higher crystallinity, higher deep trap density, and the lower carbonyl index are found to be the primary attributes of its improved performance. It is postulated that these significantly unchanged attributes can be the reason for the better anti‐thermal aging properties of the XLPE nanocomposite.

中文翻译：

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交联聚乙烯/ MgO纳米复合材料对±320 kV高压直流电缆的电绝缘性能

聚合物纳米复合绝缘材料正受到电缆行业的广泛关注。本文介绍了纯正XLPE的商用320 kV高压直流（HVDC）交联聚乙烯（XLPE）/ MgO纳米复合材料的电绝缘性能。迄今为止，尚未报告这种商用级电绝缘材料的结果。扫描电子显微镜证实了聚合物基质内部分散良好的纳米填料。通过直流击穿强度，空间电荷，直流电导率和表面电势衰减测量来研究直流电绝缘性能。将测试样品在135℃下进行30天的热老化。未老化的纳米复合材料的直流击穿强度高出20％，杂散空间电荷的累积可忽略不计，并且直流电导率比未老化的纯XLPE低一个数量级。而且，热老化的纳米复合材料显示出对其性能劣化的更多抑制。在热老化之后，纯XLPE及其纳米复合材料的直流击穿强度分别降低了38％和20％。热老化的纳米复合材料显示出可忽略的杂电荷，并且直流电导率增加了一个数量级。但是，纯XLPE表现出更高的杂电荷积累和增加的直流电导率一个数量级。在未老化的XLPE纳米复合材料中，较高的结晶度，较高的深陷阱密度和较低的羰基指数是改善其性能的主要特征。