变压器油中腐蚀性硫对铜导线及油浸绝缘纸特性影响

为研究变压器油中腐蚀性硫的存在对铜导线及油浸绝缘纸特性的影响,在实验室内对某现场已运行5年的尼那斯(Nynas)油进行了相关热老化分析。通过肉眼观察并利用扫描电镜、能谱分析等手段研究了油样老化过程中所添加铜线及绝缘纸表面的颜色变化、微观结构及元素组成;利用宽频介电谱测量了油浸绝缘纸老化前后损耗因数及介电常数的变化情况,并对绝缘纸的击穿强度进行了测试。结果表明,铜线表面的颜色变化表征了其被腐蚀的程度;变压器油中氧气浓度对二苄基二硫(DBDS)与铜导线在油中的反应无明显影响,但会影响硫化亚铜(Cu2S)在铜线、绝缘纸等表面的附着情况;Cu2S附着后会改变铜线的表面结构、绝缘纸的纤维分布,并导致油-纸复合绝缘介电性能下降。以上研究为进一步探讨变压器油中腐蚀性硫的危害及相关作用机理提供了必要的实验基础。

Influence of Corrosive Sulfur in Transformer Oil on the Copper Wire and Oil Immersed Insulation Paper

In order to research the influence of corrosive sulfur in transformer oil on the copper wire and oil immersed insulation paper,a series of thermal aging tests was carried on one kinds of Nynas oil,which had been running for five year on field,in the laboratory.The surface’s color changing,microstructure and elements component of copper line and insulation paper were analyzed by naked eyes’ examination and via scanning electron microscope(SEM) together with energy-dispersive X-ray(EDX) analyzer;the dissipation factor and permittivity of oil immersed insulation paper while before and after aging were measured by broad frequency dielectric spectroscopy,and its breakdown strength was tested as well.The results show that: the color changing of copper surface represents its corrosive level.The oxygen concentration in oil has no significant effect on the reaction between dibenzyl disulfide(DBDS) and copper,but would affect the deposited condition of copper sulfide(Cu2S) on copper wire and insulation paper surface,when there are Cu2S deposited,the copper wire surface structure and insulation paper fiber structure would change a lot,moreover,the dielectric properties of oil immersed paper would decrease.All of the above results are the basic experiment foundation for a further study on the risk of corrosive sulfur in transformer oil and related mechanisms.