Investigating passivator effectiveness for preventing silver sulfide corrosion in power transformer on-load tap changers

In this paper the effectiveness of transformer oil passivation for preventing silver sulfide corrosion in an on-load tap changer is reported. The effect of different types of corrosive sulfur compounds and their different concentrations in oil on the ability of the passivator to protect silver coated contacts is studied. Changes in oil dielectric properties after passivation is also investigated. The findings presented in this paper is beneficial to utilities who want to manage the risk of failure of transformers with known or suspected to have silver sulphide corrosion.