一起高压套管更换末屏引出装置后介质损耗因数异常分析

Analysis on Abnormal Dielectric Loss of HV Bushing after Replacement of Bushing Tap Extraction Device

套管作为变压器的重要组件,其绝缘状况的优劣直接影响着变压器的安全稳定运行,套管介质损耗因数tanδ和电容量Cx能够有效反映设备绝缘的整体老化、受潮、内部集中性缺陷等一系列问题。针对一起220 kV变压器高压侧套管介质损耗因数异常增大的特殊案例,经现场缺陷排查发现,该现象是由于更换套管末屏引出装置时外部气体侵入套管内部绝缘油中形成气泡所引起的,并通过现场模拟和理论分析对此进行了验证,同时对如何预防此类缺陷提出了相关建议。

As one of the key components in power transformer, the insulation condition of the transformer bushing directly affect the healthy and stable operation of the power transformer. A series of problems such as the overall aging, moisture, and internal concentration defects of the equipment insulation can be effectively reflected through the test of the dielectric loss factor tanδ and the capacitance Cx. This paper introduces a special case about the abnormal increase of dielectric loss of HV side bushings in a 220 kV transformer. The investigation of the cause indicates that it is caused by gas intrusion into the bushings insulation oil while changing the bushing tap extraction device, and it is verified by on-site simulation and theoretical analysis.Suggestions are put forward on how to prevent such defects.