电场对变压器绕组油纸绝缘油硫腐蚀的影响及机理研究

Study on Influence and Mechanismof Oil Sulfur Corrosion in Oil-Paper Insulation of Transformer Winding under the Electric Field

为了探究电场对变压器绕组油纸绝缘油硫腐蚀的影响及机理,在实验室将Pig-tail绕组模型浸渍于添加了典型腐蚀性硫——二苄基二硫(DBDS)的绝缘油中,在交、直流电场和热(130℃)联合作用下开展20天的油硫腐蚀试验,对腐蚀试验后的绝缘绕组和绝缘油的理化性能和电气性能参数以及绝缘纸上硫化亚铜沉积量进行测试,对比分析电场对绕组硫腐蚀的影响规律和作用机制。结果表明:相比于单一热作用,交流和直流电场的加入均能加速油硫腐蚀过程,且电场强度越大,加速效果越明显。交流电场作用下,绕组模型两电极的腐蚀程度相当;而直流电场作用下,两电极腐蚀程度不对称,与直流高压电源极性相关。分析认为,电场作用下两电极的铜条形成电解池,并发生电化学腐蚀,电极表面析出的铜离子是加速油硫腐蚀进程的主要原因。

In order to study the effect of corrosive sulfur in transformer oil on the performance of Oilpaper Insulation under electric field,a typical kind of corrosive sulfur–dibenzyl disulfide(DBDS)was added into the transformer insulating oil with Pig-tail winding model under laboratory conditions,carried out oil sulfur corrosion test under AC and DC electric field with thermal aging at 130℃for 20 days.The physicochemical properties and electrical properties of the insulating oil aged after electro-thermal impact were tested and the sulfur corrosion mechanism under the effect of electric field was studied and obtained.The results showed that the addition of AC and DC electric field could accelerate the corrosion process,and the greater the electric field intensity was,the more obvious the effect occurred.Under the AC electric field,the corrosion degree of two electrodes was similar,but under the DC electric field,the corrosion degree of two electrodes was asymmetric,which is related to the polarity of the DC high voltage power supply.It is analyzed that the copper strips of the two electrodes formed an electrolytic cell and the electrochemical corrosion occurred,copper ion released from the surface of the electrode was the main reason to accelerate the sulfur corrosion process in oil.