Evaluation of kaolin clay as natural material for transformer oil treatment to reduce the impact of ageing on copper strip

Abstract

Copper sulfide formation is one of the possible corrosion mechanisms involving the corrosive sulfur of copper. EDX scans of copper strip before and after immersing in aged transformer oils containing sulfur without copper passivator at 100°C for 3h indicated that copper sulfide was formed on the copper strip surface. The reclaimed oil by using kaolin clay reduced the sulfur content of all tested aged oils reducing the corrosion on copper strips in all samples investigated. In every case studied, the oil after reclamation by kaolin clay showed no sign at all of corrosive sulfur on the surface of copper strips. Nevertheless the atomic absorption analysis of copper ions in oil samples showed that the dissolution of copper was increased with increasing the sulfur content in the oil at different times of immersed copper strip in the oil