Corrosive Sulphur Analysis with SEM / EDS
Caused by Dibenzyl Disulfide (DBDS) corrosive sulphur has received significant attention in the HV transformer industry over the last decade.
The underlying reason for concerns started in 2000 when several large and relatively new transformers unexpectedly failed.
Subsequent investigations found fine deposits and corrosion on some of the windings and fine deposits embedded in some of the paper insulation. These deposits were identified as copper sulphide, which is an electrically conductive compound. Its presence in the paper insulation formed a conductive path, lowering the dielectric strength of the paper, therefore resulting in failure.
This copper sulphide was created when corrosive sulphur compounds in the oil reacted with the copper conductors.