电晕放电老化对高温硫化硅橡胶材料陷阱特性的影响

Influence of Corona Discharge Aging on Trap Characteristics of High Temperature Vulcanized Silicon Rubber Material

随着运行年限的增加,在役复合绝缘子的老化现象逐渐凸显,严重影响电力系统的安全。为此,首先针对在不同电晕强度(电压和时间)下老化后的高温硫化(HTV)硅橡胶试样,研究了材料表面陷阱特性、表面微观形貌(SEM)和元素特性(XPS)的变化规律,然后分析了不同年限的在役复合绝缘子伞裙材料的陷阱特性。研究表明,随着电晕电压或老化时间的增加,电子和空穴陷阱密度不断增加,最后趋向饱和水平。SEM和XPS分析结果表明,老化后材料表面出现大量孔洞等缺陷,强极性基团数量增加,分别作为物理和化学陷阱对陷阱特性产生影响。对于现场复合绝缘子伞套材料,其电子和空穴陷阱密度也呈现随运行时间增加而增长的类似规律,其中空穴陷阱密度规律性好,重复性强,有望成为一种评价复合绝缘子材料老化的新型定量表征参数。

Taking high temperature vulcanized （HTV） silicone rubbers aged under different corona intensity （voltage and time） as example,we comparatively investigated the changing rules of surface trap characteristics, surface microstructure （SEM）,and element characteristics （XPS） of the samples. Then, we investigated the surface trap characteristics of aged insulator samples from different-operated-year sites. Experimental results show that, along with the enhancement of corona discharge intensity via increasing corona voltage or aging time, electron and hole trap density both increase and finally reach their saturation levels. The SEM and XPS analysis results show that the aged material surface appears to have more defects such as holes and flaws, and also have many new chemical radicals of strong polarity, remarkably affecting the surface trap characteristics as physical and chemical defects, respectively; both electron and hole trap density of specimens of field ageing insulators increase with the operation time. Moreover, the hole trap density time-changing rule shows good regularity and repeatability, thus it is expected to be a novel quantitative parameter for effectively evaluating material ageing of composite insulator.