加速热老化对硅橡胶击穿及电荷输运特性的影响

Effect of Accelerated Thermal Ageing on Breakdown and Charge Transport Properties of Silicone Rubber

实际服役的220 kV高压电缆附件用硅橡胶材料在180℃下进行加速热老化,对老化后试样的交流击穿特性、表面电位衰减特性以及交联密度进行测试与分析。结果表明:随着热老化时间的增加,硅橡胶材料的击穿强度先增大后减小,在老化14 d时达到最大值。随着老化时间的增加,硅橡胶材料的电荷迁移率先减小后增大,在老化14 d时达到最小值。结合交联密度的测试结果分析认为,在老化初期,硅橡胶分子链段进一步交联,交联密度有所提升,硅橡胶对电荷的束缚能力增强,导致电荷迁移率减小,击穿强度增大。随着老化程度的加深,硅橡胶交联结构逐渐被破坏,交联密度减小,对电荷的束缚能力减弱,导致电荷迁移率增大,击穿强度减小。

The silicone rubber used for 220 kV high voltage cable accessories was accelerated thermal aged at 180℃,and the AC breakdown properties,surface potential decay properties,and cross-linking density of the aged sample were measured and analyzed.The results show that with the increase of ageing time,the breakdown strength of the silicone rubber increases at first and then decreases,and reaches the maximum value after aged for 14 days.With the increase of ageing time,the charge mobility decreases at first and then increases,and reaches the minimum value after aged for 14 days.According to the test results of cross-linking density,at the early ageing stage,the silicone rubber molecular chains are further cross-linked,the cross-linking density increases,and the binding capacity of silicone to charge is enhanced,leading to the decrease of charge mobility and the increase of breakdown strength.With the deepening of ageing degree,the cross-linking structure of silicone rubber is destroyed gradually,the cross-linking density decreases,and the binding capacity to charge is weakened,leading to the increase of charge mobility and the decrease of breakdown strength.