Corrosion Failure Analysis of Contactor Type Electrical Connection Components Used in Converter Valve Side Bushings

ABSTRACT As a commonly used bushing current‐carrying structure in recent years, contactor‐type electrical connection parts operate in a complex environment of electric, thermal and chemical corrosion for extended periods. With the increase of ultra‐high voltage (UHV) transmission capacity, its operating environment faces more stringent challenges, and the stability of their operation is directly linked to the reliability of the UHV transformer equipment. This paper aims to investigate the mechanism behind contact failure by developing a contactor deterioration test platform in oil to study the deterioration and corrosion process of strap contactor in oil under 120°C environment. The study found that the sulphur element content on the exposed copper surface of the strap contactor was elevated from 0% to 2.05% in 28 days, and there was an obvious latency period for the sulphide corrosive reaction with the surface of the strap contactor. The electrical contact resistance of the strap contactor after the corrosion reaction was elevated from 110 to 251 μΩ, which became overheating failure and contact failure of electrical connection components of bushings.