交变载荷下绝缘拉杆用GFRP电树枝劣化特性

Electrical Treeing Degradation Characteristics of GFRP Composites forInsulated Pull Rods Under Alternating Mechanical Loads

气体绝缘组合电器(gas insulated switchgear,GIS)现场调试或运行过程多次发生绝缘拉杆内部击穿问题,影响工程投运与设备可靠性,迫切需要探明故障机理。该文选取GIS断路器绝缘拉杆用玻璃纤维增强环氧树脂复合材料(glass fiber reinforced epoxy resin composite,GFRP)为研究对象,通过计算分、合闸下绝缘拉杆主应力分布特性,设置交变载荷下电树枝劣化实验条件,研究不同交变载荷对GFRP内电树枝生长特性影响规律。结果表明,相较于单一载荷,交变载荷条件下GFRP中电树枝生长速度加快,平均击穿时间降低,击穿概率增大。基于复合材料力学仿真发现交变载荷下GFRP内树脂-纤维界面处会出现较大的应力集中,局部应力损伤已达到失效的临界值。综上,交变载荷下绝缘拉杆纤维-树脂界面机械损伤与绝缘劣化交互演进是造成绝缘击穿的主要原因,也可作为试验考核与结构设计的改进依据。

There have been multiple internal breakdown faults of the insulated pull rods during the field testing or operation of gas insulated switchgear(GIS).These faults can affect the engineering operation and equipment reliability,thus urgently necessitating the exploration of their underlying fault mechanisms..In this paper,glass fiber reinforced epoxy resin composite(GFRP)for insulated pull rod of GIS circuit breaker is selected as the research object.The experimental conditions of electrical treeing degradation under alternating loads are set up by calculating the principal stress distribution characteristics in the insulated pull rod during the switching.The effects of different alternating loads on the growth characteristics of electrical tree in GFRP are studied.The results show that compared with congener load,the growth rate of electrical tree in GFRP increases,the average breakdown time decreases and the breakdown probability increases under alternating load.With the help of ABAQUS,it is found that there will be large stress concentration at the fiber-resin interface of GFRP under alternating loads and the local stress damage has reached the critical failure value of GFRP.In summary,the interactive evolution of mechanical damage and insulation degradation at the fiber-resin interface of insulation pull rod under alternating loads is the main cause of insulation breakdown,and it is also the improvement basis for experimental assessment and structural design.