不同状态下220 kV硅橡胶电缆接头材料微观结构和性能研究

Microstructure and Properties of Joint Material for 220 kV Silicone Rubber Cable at Different Status

为研究硅橡胶材料的老化特征,分别选取全新未运行、正常运行提前退役和运行中发生故障的220 k V硅橡胶电缆接头,通过测量凝胶含量和傅里叶红外光谱研究接头绝缘材料的微观结构变化;并对其拉伸和抗撕裂强度等力学性能,以及相对介电常数、介质损耗因数、体积电阻率和电气强度等电气性能进行测试分析。结果表明:在电、热、力老化或接头故障产生的短时高温作用下,硅橡胶绝缘的交联网络受到一定程度的破坏,从而使拉伸强度降低,断裂伸长率升高,同时体积电阻率明显下降。相较全新试样,退役试样和故障试样的绝缘-半导电界面撕裂强度均有所下降。运行状态对绝缘材料的介电强度没有显著的影响。

In order to study the ageing characteristics of silicone rubber material, 220 k V silicone rubber cable joints of new（no operation）, early retirement（normal operation）, and malfunction（during operation）were selected, respectively. The microstructures of joint insulating materials were studied by gel content test and Fourier transform infrared spectroscopy（FTIR）. The mechanical strength such as tensile strength and tear strength, the electrical properties such as relative dielectric constant, dielectric loss factor, volume resistivity, and electrical strength of the joint insulating materials were measured. The results show that under the short-time high temperature caused by electrical, thermal, and force ageing or joint failure,the cross-linked networks of silicone rubber insulating material are damaged to a certain extent, so that the tensile strength decreases and the elongation at break increases, at the same time the volume resistivity decreases. Compared with the new samples, the tear strength of the interface between insulation and semiconduction layer of retired and failure samples decrease. Operation states have no obvious effects on the dielectric strength of insulating materials.