LDXLPE架空绝缘电缆失效有限元分析与改性研究

Failure, Finite Element Analysis and Modification Study on LDXLPE Overhead Insulated Cables

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 were carried on the 10 kV low density crosslinked polyethylene（LDXLPE） overhead insulated cables, the results indicate that, the failure of LDXLPE insulating material is mainly due to the decrease of mechanical properties in using process of insulated cables, which later leads to lightning-caused breaking, water tree aging and electrical tree aging. In order to increase the mechanical properties of insulating material, the lignin was added into LDXLPE as the modifier, then the structure and properties of the modified LDXLPE were investigated. The results show that when the mass fraction of lignin is no more than 10%, the softening temperature of modified LDXLPE is almost unchanged, but flowability and tensile properties decrease slightly. After aging test, the tensile strength of the modified LDXLPE drops slower than that of pure LDXLPE, bur the elongation at break increases firstly and then decrease. Moreover, the impact strength of the modified LDXLPE is higher than that of other samples at the same experimental conditions. In the aging process, the carbonyl group does not appear in the modified LDXLPE, the weight loss rate and the degree of chain scission decrease, and the weight loss temperature increases.