Study on the Protective Effects of TTA, Irgamet39 and T571 Passivators on Multiple Corrosive Sulfides

The corrosive sulfur phenomenon has decades of history and currently adding passivators to the transformer oil is the most effective way to suppress the corrosive sulfur problem. However, it has not been reported how to choose the passivator concentration with different kinds of corrosive sulfur or different aging degree. In this paper, dibenzyl disulfide (DBDS) and dodecyl mercaptan (DDM) were added to the non-corrosive 25# transformer new oil, also with different concentrations of Irgamet 39, T571 and TTA. The accelerated thermal aging test was carried out at 150 °C temperature, and the corrosive extent of copper surface were observed to obtain the best concentration of passivators for different sulfurs. The accelerated thermal aging test were also carried out at a temperature of 130 °C for different aging degree. The passivators were added to the oil and the corrosion extent of copper surface were observed to get the best passivator concentration for oil with different aging degree. Results show that three passivators have different protective effects for different corrosive sulfurs. Irgamet 39 has a better protective effect than others at low concentration. However, both three kinds of passivators have poor protective effect on dodecyl mercaptan, and a new kind of passivator need to be developed. For different aging degree oil, the passivators also have different protective effect. For the transformer oil of higher aging degree, the passivators in low concentration have poor protective effect, thus the passivator content need to be concerned to make it sure at high concentration level. The research work can provide some reference for guiding the addition of passivator in practical engineering and preventing the occurrence of sulfur corrosion failure.