环氧树脂绝缘子合模缝对水扩散试验的影响

Influence of Closing Joints of Epoxy Resin Insulator on Water Diffusion Test

脂环族环氧树脂绝缘子因其优异的电气性能和良好的芯棒–护套界面粘接能力,有望广泛应用于输电线路上。由于采用自动压力凝胶成型工艺,环氧树脂绝缘子上会存在2条竖直合模缝。为研究环氧树脂绝缘子的耐水侵害能力,参照水扩散试验方法,测量环氧树脂绝缘子的泄漏电流。试验发现合模缝使得环氧树脂绝缘子水扩散泄漏电流有效值异常增大,且电压和泄漏电流相位差随着水煮时间的增大而迅速减小。为研究泄漏电流异常增大及电压电流相位差迅速减小的原因,对水煮前后合模缝处和非合模缝处分别取样进行了热失重、傅里叶红外光谱、扫描电镜和能谱试验。研究发现,合模缝处含有更多的SiO2填料导致在水煮的过程中环氧树脂基体以及基体和填料的界面更容易受到湿热环境的破坏,从而使得合模缝处环氧树脂复合材料绝缘性能下降。通过调整绝缘子模具的相对位置和在成型过程中增加环氧树脂绝缘子护套材料在模具中的流动性,可以有效改善合模缝处的填料分布,避免水扩散泄漏电流异常增大。

1:Because of its excellent electrical performance and good adhesion between core and sheath,cycloaliphatic epoxy resin insulator is expected to be widely used in transmission lines.Because of the automatic pressure gel forming process,there are two vertical joints on the epoxy resin insulators.In order to study the water resistance of epoxy resin insulator,the leakage current is measured in this paper referring to the water diffusion test method.It is found that the effective value of the leakage current of epoxy resin insulator increases abnormally due to the joints,and the phase difference between the voltage and the leakage current decreases rapidly with the boiling time.To find the reasons,TGA,FTIR,SEM and EDS tests are carried out on the joint and the non-joint areas before and after boiling.It is found that more SiO2 fillers are contained on the joints,which makes the epoxy resin matrix and the interface between the matrix and the fillers more vulnerable to the damage in the hot and humid environment in the process of boiling,so that the insulation of the epoxy resin composite at the joints will be reduced.The filler distribution at the closing joints can be effectively improved by adjusting the relative positions of the molds of the insulators and increasing the fluidity of the epoxy resin insulator sheath material in the molds during the forming process,then the abnormal increase of water diffusion leakage current can be avoided.