The oil-immersed louver contacts

a critical current-carrying component connecting the valve-side lead and bushing of ultra-high voltage (UHV) converter transformers

pose significant safety risks due to performance degradation during long-term operation. This study conducts current- carrying temperature measurement tests

establishes an electro-thermal expansion model

and evaluates the fretting wear distance of contact louvers. Combined with the operating conditions of the valve-side elevated bushing

the failure mechanisms of the oil-immersed louver contacts are clarified. Using scanning electron microscope (SEM)

energy spectrum (EDS)

and metallographic analysis

the corrosion mechanism of silver-plated copper in oil is revealed

the failure evolution process is elucidated

and a method for suppressing degradation is proposed. The research indicates that wear in the electrical contact area is the initial cause of degradation; pitting and crevice corrosion induced by thermal expansion of silver-plated copper represent a critical stage of failure; and under alternating thermal stress

and the creep of the strap stainless steel ultimately causes the contact louvers to lose its conductivity. Based on these findings

this paper proposes the adoption of a new hard silver coating method

which significantly enhances wear and corrosion resistance while maintaining the high conductivity of the louvers. The research results provide a theoretical basis and technical support for the reliability design of oil-immersed electrical contact components. contact components.