“Corrosive sulfur without DBDS – C2” is the criticality of the corrosive property of oil and other insulating liquids with respect to the metallic surfaces of which some components (e. g. copper conductors or silver contacts) inside transformers and other electrical equipment are made. This criticality is caused by the presence of sulfur compounds (other than DBDS) such as polysulfides and disulfides. “Corrosive sulfur without DBDS – C2” occurs at normal operating conditions of the transformer.
Corrosive sulfur – Free sulfur and corrosive sulfur compounds detected by subjecting metals such as copper ti contact with an insulating liquid under standardized conditions [from IEC 62697-1 of 2012, par. 3. 1. 6 – page 10]
