硫腐蚀对绕组绝缘电寿命的影响及导致绝缘失效的故障机制研究

硫腐蚀沉积已被证实会导致油浸式电力设备绝缘性能下降,进而引发绝缘故障。为探究硫腐蚀对设备绝缘击穿特性的影响,并进一步分析其导致绝缘失效的故障机制,在实验室制备了3种不同硫腐蚀程度的绝缘绕组样品,利用多样品绝缘材料的电老化试验平台,对3种不同硫腐蚀程度的绝缘绕组,分别开展了其短期击穿试验与4个不同电压下的加速电老化试验,并以绝缘击穿失效作为电寿命终点,以反幂函数作为电寿命模型,分别计算对比了其寿命指数。结果表明:硫腐蚀污染对多层绝缘纸包覆的绝缘绕组短期击穿强度影响不大,但会降低绕组的长期电寿命;相比于无腐蚀绕组样品,严重硫腐蚀绕组样品的电寿命指数下降了约19.38%,硫腐蚀产物在绕组上的沉积会明显导致绕组的长期电寿命下降。进一步结合不同硫腐蚀程度绕组样品的绝缘纸层的理化/电气特性参数变化测试结果,探讨了硫腐蚀沉积导致绕组绝缘失效的故障机制。

Investigation on the Influence of Sulfur Corrosion on Insulation Winding Electrical Life and the Mechanism of Insulation Failure Induced by Copper Sulfide

Sulfur corrosion has been proved to significantly decrease the insulation performance of oil-immersed equipment,leading to insulation failure.In order to explore the influence of sulfur corrosion on the breakdown characteristics of equipment insulation and further analyze on the mechanism of insulation failure induced by sulfur corrosion,insulation winding samples with three different sulfur corrosion degrees were prepared under the same condition,thereafter,the short-term breakdown tests and long-term electrical life tests for the three kinds of samples were carried out under a multi-insulation material electrical life test platform,respectively.By taking the insulation breakdown failure as the end of life,and taking the inverse power function as the electrical life model,the index of life expectancy was calculated and compared.Experimental results showed that the effect of sulfur corrosion on the short-term breakdown strength of insulation winding was not obvious,but it could significantly reduce the long-term electrical life of insulation winding,compared with the non-corrosive winding samples;the electrical life index of severe sulfur corrosion samples decreased by about 19.38%,and the deposition of Cu2S on the insulation winding obviously lead to the decrease of the electrical life of insulation winding.Finally,the mechanism of insulation failure induced by sulfur corrosion was investigated by measuring and analyzing the physical and chemical/electrical parameters of insulating paper layers of insulation winding sample with different sulfur corrosion degree.