There is not one single corrosive sulfur compound that is responsible for all corrosive sulfur issues that
are present in all mineral oil filled electrical apparatus. Depending on the oil, there can be tens to
hundreds of different sulfur compounds present in the oil. Of these, only a small fraction are corrosive or
are compounds that can degrade from stable species into ones that are reactive. This is usually based on
time and temperature. Only a very few corrosive sulfur compounds have been identified of which
dibenzyl disulfide (DBDS) is one. This paper only concentrates on DBDS. The reason is that it has been
found in many oils that have resulted in recent failures (2000-2007) of transformers or reactors due to
corrosive sulfur attack and the formation of copper sulfide.