Influence of metal deactivator concentration on copper sulfur corrosion in transformer oil

Insulating oil plays an important role of insulation in transformers. However, copper sulphide deposition on oil-paper insulation can lead to insulation failures in power transformers. In order to research the corrosive properties after adding dibenzyl disulfide (DBDS) and 2, 6-Di-tert-butyl-4-methylphenol (DBPC), and the ability of inhibiting corrosion after adding metal deactivator in transformer oil, a series of thermal aging tests are carried on a certain brand of Nynas and Karamay oil in this paper. First of all, testing the corrosive sulfur compounds by ASTM D1275B method; And Nynas oil test after adding a certain amount of metal deactivator is made at 90 °C to analyze the changing of dissolved gas-in-oil content is analyzed. Experiments and analysis results show that DBDS instead of DBPC is the corrosive sulfur compounds; Metal deactivation agent can effectively prevent the occurrence of sulfur corrosion, but it consumes rapidly with the thermal aging; the oil dissolved gas content significantly changes after adding metal deactivator in oil. All of the above results can be the foundation for a further study on corrosive sulfur and control measure in transformer oil.