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对10kV低密度交联聚乙烯(LDXLPE)架空绝缘电缆进行了有限元分析和失效分析,结果表明,LDXLPE绝缘电缆在使用过程中力学性能下降是失效的主要原因,进而导致后期雷击断线和水树、电树老化。为提高LDXLPE架空绝缘电缆的力学性能,采用木质素对LDXLPE进行改性,并考察了改性LDXLPE的结构和性能。结果表明:当木质素的添加量不超过10%(质量分数)时,LDXLPE的维卡软化温度几乎未发生变化,流动性能和拉伸性能则稍有降低。老化实验后,改性LDXLPE的拉伸强度的下降速度远低于未改性样品,断裂伸长率则先增大后减小,而冲击强度基本高于同实验条件的其他样品。另外老化实验后,改性LDXLPE没有出现羰基,断链程度及失重率降低,初始分解温度提高。
The finite element analysis and failure analysis of 10kV LDXLPE overhead insulated cables are carried out. The results show that the mechanical properties of LDXLPE insulated cables are the main reasons for the failure, which leads to the disconnection of lightning and water Tree, electric tree aging. In order to improve the mechanical properties of LDXLPE overhead insulated cables, LDXLPE was modified with lignin and the structure and properties of modified LDXLPE were investigated. The results show that the Vicat softening temperature of LDXLPE hardly changes when the content of lignin is less than 10% (mass fraction), while the flowability and tensile properties decrease slightly. The degradation rate of modified LDXLPE is much lower than that of unmodified sample after aging test, while the elongation at break increases first and then decreases, while the impact strength is basically higher than other samples with the same experimental conditions. In addition, after the aging experiment, the modified LDXLPE did not appear carbonyl, the degree of chain scission and weight loss decreased, the initial decomposition temperature increased.