Study on the influence of surface state of copper conductor of oil-immersed power transformer on sulfur corrosion

The sulfur corrosion of copper conductors in oil-immersed transformers is affected by the corrosive sulfur content, atmosphere, operating temperature, etc. However, both laboratory studies and field evidences indicate that the influence of the covering state of copper conductors on corrosion should not be ignored. Hence, this paper focuses on the impact of different covering status, including the covering materials and the number of the layers of insulating paper, on the corrosion of copper conductors in thermal aging. The result shows that the existence of a particular gap between the copper conductor and the covering layer is a significant factor to the sulfur corrosion of copper conductors by the concentration cell effect. Insulating paper around copper contributes to a region concentrated with DBDS, Cu
²⁺
, H
⁺
and other substances due to the adsorption and impediment effect of insulating paper, which plays a key role in facilitating the sulfur corrosion of copper conductors.