10 kV交联聚乙烯电缆加速电老化特性研究

Accelerated Electrical Ageing Characteristics of 10 kV XLPE Cable

在电应力长期作用下,XLPE电缆易发生绝缘老化。为研究XLPE电缆的电老化特性,对10 kV XLPE电缆进行加速电老化实验,并对老化前后样本进行理化性能及介电性能测试。结果表明:电老化后XLPE结晶度明显降低,熔融峰特征温度出现小幅下降;XLPE亚甲基含量有所上升,材料内部出现碳碳双键;PDC测试结果表明,电老化后样品极化电流和去极化电流均有所上升,XLPE电导率和低频介质损耗明显增加。由此可知,高能电子撞击使XLPE分子链发生化学键断裂,从而造成小分子链数量增多以及结晶区破坏,进而导致材料的理化性能和介电性能下降。

XLPE cable insulation is prone to age under the long-term influence of electrical stress. In order to study the electrical ageing characteristics of XLPE cable, we conducted accelerated electrical ageing experiments on 10 kV XLPE cable, and the physic-chemical properties and electrical properties of the XLPE cable before and after ageing were investigated. The results show that the crystallinity of XLPE decreases significantly after electrical ageing, and the melting peak characteristic temperature of XLPE decreases slightly. The methylene content of XLPE increases, and carbon-carbon double bonds start to appear inside the material. PDC test results show that the polarization and depolarization current of the samples increase after electrical ageing, and the conductivity and low frequency dielectric loss of XLPE increase significantly. This is because the chemical bond break in XLPE molecular chain is broke by high-energy electron bombardment, resulting in the increase of shortchain molecules number and degradation of crystalline region, which ultimately decrease the physic-chemical and electrical properties of XLPE insulation material.