真空紫外辐照对硅橡胶直流击穿和沿面闪络特性的影响

Influence of Ultraviolet Irradiation in Vacuum on DC Breakdown and Surface Flashover Characteristics of Silicone Rubber

电力系统复杂的工作环境会导致硅橡胶材料发生击穿和沿面闪络。首先对硅橡胶试样在真空环境下进行紫外射线辐照处理24 h,并测试了处理前后硅橡胶试样的直流击穿和沿面闪络特性;然后采用介电谱计算了材料中的活化能和松弛时间分布,并采用表面电位衰减分析了陷阱特性;最后采用红外光谱图分析了硅橡胶分子链发生的化学反应。研究结果表明:经过真空紫外光处理后,硅橡胶材料分子链发生了交联,内部偶极子转向极化的活化能增加,分子链松弛时间减小,运动更困难,进而增大了材料的陷阱深度,抑制了材料的电荷输运过程;直流击穿场强和沿面闪络电压分别提高了2.38%和8.79%;在低于5×10-4 Pa的真空紫外光辐照环境下处理24 h后,硅橡胶复合材料的分子链运动和电荷输运过程受到抑制,直流击穿和沿面闪络性能获得了有效提高。上述研究结果可为解决硅橡胶中直流击穿和沿面闪络问题提供参考。

Breakdown and surface flashover are likely to occur on silicone rubber in the complex operation environments of electrical system.Firstly,silicone rubber specimens were treated by ultraviolet irradiation in vacuum for 24 hours,and DC breakdown and surface flashover characteristics of treated and untreated specimens were tested.Then,the activation energy and relaxation time distribution were calculated by dielectric relaxation spectroscopy.The trap characteristics were analyzed by surface potential decay.Finally,the chemical reaction of silicone rubber molecular chains was characterized using infrared spectroscopy.The results indicate that the molecular chains of silicone rubber crosslink via ultraviolet irradiation in vacuum,the activation energy of dipolar orientation polarization increases,while the molecular chain relaxation time decreases and molecular chain dynamic is hindered,which can improve the trap level and suppress the charge transport process of silicone rubber.DC breakdown strength and surface flashover voltage will increase by 2.38%and 8.79%,respectively.The molecular chain dynamic and charge transport process of silicone rubber,which is irradiated by ultraviolet in vacuum of which pressure is lower than 5×10-4 Pa for 24 h,are suppressed,thus the DC breakdown and surface flashover characteristics will be enhanced efficiently.The results can provide references for solving breakdown and surface flashover in silicone rubbers.