Ageing and corrosion of paper insulated copper windings: the effect of irgamet?? 39 in aged insulated oil

Copper sulphide can be formed on copper windings in high voltage transformers and cause dielectric breakdown in the transformers. To avoid transformer failures caused by copper sulphide, metal passivators are added to the insulating oil. Here, the commonly used metal passivator Irgamet^® 39 was used in combination with copper surfaces, sulphides and insulating oil in order to investigate the effect of the passivator. Traditional methods such as ageing experiments supplemented by Quartz Crystal Microbalance experiments were used to investigate the effect of Irgamet^® 39. The results showed no effect of Irgamet^® 39 on the corrosion of copper in systems where the formation of copper sulphide had started, while the effect was found to be very good on fresh copper surfaces.