Long-term thermal ageing might have impacts on the physicochemical properties of cross-linked polyethene (XLPE) cables, thereby influencing their electrical behaviours, such as electrical treeing initiation and growth. The main objective of this work is to report the effects of thermal ageing on the electrical treeing behaviours (initiation and growth) in XLPE cable insulation. For this purpose, the electrical treeing initiation and growth test were performed in accelerated thermal samples. In addition, Differential Scanning Calorimetry and Fourier Transform Infrared Spectroscopy were utilised to investigate corresponding changes in the microstructures of materials. In addition, a correlation was established between electrical treeing behaviours and physicochemical properties during the thermal ageing process. Test results indicate that the thermal ageing process should be divided into three phases, and the re-crystallisation reaction is considered the primary reason for the increase of average electrical tree initiation voltage (AETIV). Furthermore, the thermal ageing index X_c is correlated to AETIV and the propagation rate of the electrical tree. As equivalent relationships have been established between the relative decrease value w of indexes AETIV, the propagating rate and X_c, this method can be employed to predict the changing pattern of electrical treeing initiation voltage and the propagating rate in future research.

中文翻译：

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热老化后交联聚乙烯电缆的电树行为

长期热老化可能会对交联聚乙烯 (XLPE) 电缆的物理化学性质产生影响，从而影响其电气行为，例如电树的引发和生长。这项工作的主要目的是报告热老化对 XLPE 电缆绝缘中电树行为（起始和生长）的影响。为此，在加速热样品中进行电树引发和生长测试。此外，还利用差示扫描量热法和傅里叶变换红外光谱来研究材料微观结构的相应变化。此外，在热老化过程中，电树枝行为和物理化学性质之间建立了相关性。测试结果表明，热老化过程应分为三个阶段，再结晶反应被认为是平均电树起始电压（AETIV）增加的主要原因。此外，热老化指数X _c与 AETIV 和电树的传播速率相关。由于AETIV指标的相对下降值w、传播速率和X _c之间建立了等效关系，因此在今后的研究中可以采用该方法来预测电树起爆电压和传播速率的变化规律。