Improving sulfur corrosion resistance of transformer windings by grain boundary engineering technology

A metal passivator is often added to transformer oil to inhibit oil sulfur corrosion. However, the addition of passivator can result in gaseous anomaly in the oil and need to be added regularly. In this paper, the copper winding of transformer is treated by grain boundary engineering technology, and the corrosion resistance of the winding before and after treatment is compared according to IEC 62535 standard. The experimental results show that the copper windings treated by grain boundary engineering technology have good corrosion resistance. The original copper winding began to corrode when dibenzyl disulphide (DBDS) concentration achieved 50 mg/kg. Even DBDS concentration was up to 2000 mg/kg, the treated windings still had a good anticorrosion effect. Further, corrosion resistance mechanisms were explored, it is found that the corrosion resistance of the treated winding is better than that of addition passivator. The statistical analysis of the internal grain boundary of the copper windings shows that the twin grain boundary of treated windings increases obviously, and the increased twin grain boundary breaks the connectivity of the grain boundary, thus improving the corrosion resistance of the windings.