Mechanism of Deterioration of Oil Immersed Louver Contact on Valve Side of UHV Converter Transformer

The oil-immersed louver contact is a critical current-carrying connector between the winding outlet line and the bushing in the ascending flange on the valve side of the UHV converter transformer. This paper investigates the degradation evolution mechanism of the oil-immersed louver contact. Using finite element simulation, SEM-EDS analysis, metallography, microhardness testing, and low-temperature heat treatment experiments, we focus on the wear, corrosion, and plastic deformation characteristics of louvers. The results indicate that vibration-induced wear are the main causes of deterioration of louver contacts. Insulating oil invades the interior of the louvers through damaged silver coating, leading to crevice corrosion along the interface between the copper substrate and silver coating. The combined effects of crevice corrosion, copper sulfur corrosion, and pitting corrosion create a unique “sandwich” corrosion structure, causing continuous heating of the louver, which can reach up to 400 °C. Consequently, chromium-rich carbides precipitate from the stainless steel skeleton, causing plastic deformation of the louver contact. These findings provide valuable references for the design of oil-immersed electrical contact components and failure analysis.