Suppressive mechanism of the passivator irgamet 39 on the corrosion of copper conductors in transformers

Abstract

Transformer oil samples were divided into two groups and classified according to the presence or absence of Irgamet 39, a metal passivator. After 48 h reaction at 150 oC, the copper strips were characterized by scanning electron microscopy, and attenuated total reflection Fourier transform infrared spectroscopy. The results showed that Irgamet 39 bonded to copper surfaces and created an impermeable boundary between the bulk of the metal and the surrounding insulating cellulose and oil. This boundary protected the copper from corrosion. Time-of-flight secondary ion mass spectroscopy results showed that Irgamet 39 appeared to lose its aminomethyl tail upon binding to form a Cu-TTA complex. From the copper content, acid value, and oxidation stability test results of reacted oil, as well as the interfacial tension, dielectric loss tangent, volume resistivity, and electrostatic charging tendency test results of unreacted oil, Irgamet 39 was found to improve the oxidation stability and dielectric loss tangent of transformer oil. No negative influences toward interfacial tension, electrostatic charging tendency and volume resistivity were observed. The passivator film formed on copper strip was stable at high temperature and oxygen conditions. Excessive application of Irgamet 39 would decrease the performance transformer oil.