变压器油中腐蚀性硫浓度对绕组绝缘电气性能的影响

为了研究变压器油中腐蚀性硫含量对绕组绝缘性能的危害,通过在变压器绝缘油中添加二苄基二硫(DBDS),以得到三种浓度含腐蚀性硫的绝缘油样品,并将纸包铜绕组浸渍于绝缘油样品中,在130℃下开展加速热老化试验。在不同老化时间取样试品测量相关参数以研究绝缘纸上沉积物的特性、发展规律及其对绕组模型绝缘性能的影响。通过SEM观察铜导线与绝缘纸表面微观形貌变化规律,采用能谱分析技术确定绝缘纸表面沉积物质的元素及含量,利用Keithley6517B测试沉积量对绕组的体积/表面电阻率以及介质损耗参数影响规律。试验结果表明,油中的DBDS含量增加可明显加速铜片表面的腐蚀速度及绕组绝缘纸上腐蚀性物质的沉积,沉积于绝缘纸表面的物质会对绝缘的体积/表面电阻率、介质损耗造成明显的影响。以上研究对深入认识变压器油硫腐蚀机理及有效预防此类事故的发生具有重要意义。

The Influence of Corrosive Sulfur Contentation in Transformer Oil to the Electrical Properties of Insulated Windings

In order to study the harm of corrosive sulfur in transformer oil to insulated windings, three different contents of corrosive sulfur–dibenzyl disulfide(DBDS) are added into the transformer insulating oil under laboratory conditions, paper copper winding model containing corrosion gets from oil-paper insulation under the accelerated thermal aging at 130℃. Use SEM to observe the Micro–Topography on the surface of copper wire and insulating paper, and then use spectrum analysis techniques to determine the elements content of the material deposited on the surface insulating paper, use Keithley 6517B to test resistivity and dielectric loss of volume / surface of windings with different amount of corrosion and calculate the frequency relative permittivity. The results show that oil with high contents of DBDS can significantly accelerate the deposition of corrosive substances on the surface of the winding insulation and corrosion of copper. With more DBDS added, more sediments are produced on the insulating paper, what's more, the volume/surface resistivity and the dielectric loss change clearly. The studies are significant to further understand the mechanism of transformer oil with sulfur corrosion and to prevent the occurrence of such accidents effectively.