In this study, 238 power transformers (PTs) with operating voltages between 150-500 kV and capacities in the range of 60-167 MVA are tested for partial discharge (PD). Thirty-eight of the PTs exceeded the pre-determined value of 70 pC at 1.5 maximum voltage of the PT. Failure analysis of the failed 38 PTs showed that 21% of the PD sources originate from the winding cylinder, which is formed by bonding the edges of a pressboard with an adhesive. Therefore, in this study, the effect of casein- and polyvinyl-based adhesives used in winding cylinders was investigated through standard PD measurements. The results indicate that pressboards bonded with casein-based adhesives exhibit PD values 20-25 pC lower than those bonded with polyvinyl-based adhesives (50-400 pC) at identical applied voltages (7.5-25 kV or 3-10 kV/mm). The excellent performance of casein-based adhesives is mainly attributed to its porous structure, which accelerates the impregnation of oil into the adhesive and pressboard, as revealed by scanning electron microscopy observations. This practical study will be beneficial in the process of designing and manufacturing PTs and highlight materials for producing PTs with low PD values.

中文翻译：

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不同粘合剂对电力变压器绕组筒体绝缘局部放电的影响


在这项研究中，对工作电压在 150-500 kV 之间、容量在 60-167 MVA 范围内的 238 个电力变压器 (PT) 进行了局部放电 (PD) 测试。 38 个 PT 在 1.5 倍 PT 最大电压下超过了预定值 70 pC。对失效的 38 个 PT 进行故障分析表明，21% 的局放源源自缠绕圆筒，该缠绕圆筒是通过用粘合剂粘合纸板边缘而形成的。因此，在本研究中，通过标准 PD 测量研究了缠绕圆筒中使用的酪蛋白和聚乙烯基粘合剂的效果。结果表明，在相同的施加电压（7.5-25 kV 或 3-10 kV/mm）下，使用酪蛋白基粘合剂粘合的纸板的 PD 值比使用聚乙烯基粘合剂粘合的纸板 (50-400 pC) 低 20-25 pC 。扫描电子显微镜观察表明，酪蛋白基粘合剂的优异性能主要归功于其多孔结构，这加速了油对粘合剂和纸板的浸渍。这项实践研究将有益于 PT 的设计和制造过程，并重点介绍用于生产低 PD 值 PT 的材料。