伞套硅橡胶含量对复合绝缘子运行寿命的影响

Influence of Silicone Rubber Content of Shed and Sheath on Composite Insulator Lifespan

现有技术的硅橡胶复合绝缘子运行寿命仅10~20 a,远低于瓷/玻璃绝缘子的50~100 a寿命。考虑到相对集中的老化风险和密集更换的巨额投入,该产品在不远的将来可能成为电网隐患,因此大幅度提升复合绝缘子寿命已成为亟待解决的问题,其中酥朽缺陷频发和防污闪性能下降是影响寿命的两大焦点。基于运行统计、电场分布计算、酥朽绝缘子解剖、交变屈曲–电场–温度–湿度的多因素疲劳试验及硅橡胶伞套低温机械性能测试等,验证了交变弯曲是部分酥朽的重要成因,在低温条件共同作用下易导致现有产品的低硅橡胶含量伞套劣化、开裂,从而丧失对芯棒和界面的保护作用,致使紧凑型V串、跳串等易承受弯曲荷载的绝缘子具有高酥朽占比;过于严苛的电蚀损要求已成为限制伞套胶含量及复合绝缘子寿命的瓶颈;合理突破现行标准的电蚀损参数以实现胶含量的大幅度提高,从而使伞套长久保持硅橡胶固有的耐候性、耐寒性、低温弹性及憎水迁移性已成为提升复合绝缘子寿命的关键。

The silicone rubber(SR)composite insulator is the most widely used insulator in transmission lines,but its actual lifespan is only 10~20 years,which is far less than 50~100 years of the porcelain/glass insulators.Due to the risk of aging of composite insulators and the huge investment of replacement,the composite insulator used to control pollution flashover may become a serious problem for power grid in the near future.Therefore,greatly improving the lifespan of composite insulators is an urgent problem to be solved.The decay fracture and the degradation of anti pollution flashover performance are the two focuses affecting the lifespan of composite insulators.The statistics of operating composite insulators,calculation of electric field distribution,dissection of decay fracture insulators,bend-electricfield-temperaturehumidity test and low temperature mechanical properties test of SR sheath show that the alternating bending is an important cause of cracked insulators.Under the combined effect of alternating bending and low temperature,it is easy to cause the deterioration and cracking of the sheath with low SR content,thus the protection effect on the core rod and interface may be lost,and a large percentage of decay fracture insulators may occur in the insulators that are easy to bear bending load,such as compact V-strings and jump strings.The excessively strict requirement for electric erosion of sheath is a technical mistake in the development of composite insulators,which has become a bottleneck to improve the lifespan of the composite insulator.Reasonably breaking through the electric erosion parameters of current standard to achieve a substantial increase in the SR content of sheath is the key to maximize the weather ability,cold resistance,low temperature elasticity of SR and improve the lifespan of the composite insulator.