An experimental study on the effects of DBDS in transformer oil of power transformers

Dibenzyl Disulfide (DBDS) is one of several sulfur compounds known to cause copper corrosion in transformers. Breakdown of the DBDS to benzyl mercaptan or a DBDS-Copper complex can still cause corrosion of copper and the formation of copper sulfide. The primary effect of the presence of corrosive sulfur species in insulating oil is the formation of copper sulfide (Cu₂S) on the surface of copper conductors and its subsequent migration through the insulating paper layers, leading to electrical faults. The main compound known to cause copper corrosion leading to the formation of copper sulfide is dibenzyl disulfide (DBDS). The use of metal passivators, such as Irgamet 39^TM as an additive to oil is a typical mitigation technique for suppressing the formation of copper sulfide. The addition of metal passivators to oil does not reduce or eliminate DBDS. Experimental study has been carried out to describe the role of DBDS in leakage current and breakdown of oil insulation.