水分在环氧浸纸材料中的迁移特性及其对沿面绝缘特性的影响

Migration Characteristics of Moisture in Epoxy-impregnated Paper Materials and Its Influence on Surface Insulation Characteristics

目前,国内高压直流工程中的穿墙套管和换流变压器套管多采用环氧浸纸干式套管,环氧浸纸材料具有一定的吸水性,故亟需研究环氧浸纸材料受潮过程中的水分迁移规律以及受潮前后的直流沿面绝缘性能。该文通过交直流沿面闪络测试,获取表面涂漆与未涂漆的环氧浸纸试样受潮前后的沿面绝缘强度,通过微水含量测量分析环氧浸纸的水分迁移特性。结果表明:受潮前后涂漆试样交直流沿面闪络场强较无漆试样均至少提高2.9%;相对于无漆试样,涂漆后环氧浸纸材料吸水速率降低22.1%;由于聚酰胺的吸水性导致表面层湿度同样较高,较长时间受潮后涂漆试样沿面绝缘性能依旧明显下降。结果可为环氧浸纸芯体防潮及提升其沿面绝缘性能提供理论支撑。

At present,the wall bushing and converter transformer bushing in domestic high-voltage DC projects mostly use epoxy impregnated paper dry casing.Epoxy impregnated paper materials are easy to absorb water,so it is urgent to study the water migration law of epoxy impregnated paper materials during moisture exposure and the DC surface insulation performance before and after moisture.In this paper,the surface insulation strength of the surface painted and unpainted epoxy impregnated paper specimens before and after moisture is obtained by AC/DC flashover test,and the moisture migration characteristics of epoxy impregnated paper are obtained by micro-water content measurement.It is found that the flashover field strength of painted specimens along the AC and DC surfaces before and after moisture is at least 2.9%higher than that of unpainted specimens;compared with the unpainted sample,the water absorption rate of epoxy impregnated paper material after painting is reduced by 22.1%;due to the water absorption of polyamide,the humidity of the surface layer is high,and the insulation performance along the surface of the painted specimen still decreases significantly after a long period of moisture.The results of this paper can provide theoretical support for the moisture resistance of epoxy impregnated paper core and the improvement of its insulation performance along the surface.