水分对干式套管环氧浸渍纸材料介电特性的影响

Effect of Moisture on the Dielectric Properties of Epoxy Resin Impregnated Paper for Dry-Type Bushing

干式套管电容芯子主绝缘为由皱纹纸经环氧树脂浇注而成的环氧浸渍纸。由于环氧树脂与皱纹纸分子链存在亲水性基团而易吸收水分,为了明确水分在两种材料中扩散特性及对其介电性能的影响,该文制备了环氧树脂和环氧浸渍纸绝缘样品,开展了水分扩散实验以及不同含水量下的介电特性测试实验。结果表明:纯环氧树脂中的水分扩散符合Fick扩散模型,而水分在环氧浸渍纸中的扩散特性可用Langumir模型来解释;对于纯环氧树脂,水分含量的减少仅导致介电谱曲线低频段(1mHz~1Hz)降低,对高频段(1Hz~5kHz)则基本无影响,对于环氧浸渍纸则表现为介电谱曲线损耗峰向低频方向移动;进一步地,论文提取两种绝缘介电谱曲线的特征参量,提出干式套管绝缘受潮状态评估的新方法。

The main insulation of the dry-type bushing capacitor core is epoxy impregnated paper,which is consists of crepe paper and epoxy resin.It is easy to absorb waterdue to the presence of hydrophilic groups in the molecular chains of epoxy resin and crepe paper.In order to clarify the diffusion characteristics of water in the two materials and its influence on their dielectric properties,the insulation samples of epoxy resin and epoxy impregnated paper were prepared,and the water diffusion experiments and dielectric properties tests under different water contents were carried out.The results show that the water diffusion in pure epoxy resin conforms to the Fick diffusion model,while the diffusion characteristics of moisture in epoxy impregnated paper can be explained by the Langumir model.For pure epoxy resin,the reduction of water content only leads to a decrease in the low frequency band(1mHz~1Hz),and has basically no effect on the high frequency band(1Hz~5kHz),while the loss peak of the dielectric response curve moves to the low frequency bandfor epoxyimpregnated paper.This paper extracts the characteristic parameters of dielectric response curves,and proposes a new method for the damp state evaluation of dry bushing insulation.