Tracking the Progression of Sulfur Corrosion in Transformer Oil Using Thin Film Sacrificial Copper Strip

In this work, thin film sacrificial copper strips are introduced as sensors to provide a direct indication on the corrosiveness of insulating oils. The progression of sulfur corrosion in transformer insulating oils was simulated by adding different concentrations of dibenzyl disulfide into glass Petri dishes, each containing 40 mL of non-corrosive oil. The resistive thin film copper strips were deposited onto a glass substrate using an electron beam evaporator and the strips were then immersed into the corrosive oil samples. The samples were aged in a forced convection laboratory oven at 130 °C for 20 h. The material loss due to the presence of corrosive compounds was monitored by measuring the resistance of the thin film copper strips using four-wire resistance measurements. The preliminary results reveal that the corrosive by-products (due to the breakdown of dibenzyl disulfide) accelerates the corrosion of the thin film copper strips, as evidenced from the amount of copper loss on the surface of the strips. This increases the resistance values of the thin film copper strips. Based on the variations in the resistance of the thin film copper strips, one can infer the level of sulfur corrosion in transformer insulating oils.