Scenario
Thermal power plant with 8 GSU transformers
Nameplate data of the transformers:
Power [MVA]: 175
Voltage [KV]: 400
Oil type: naphthenic oil
Step 1
The diagnosis in the 2009 showed:
Total sulfur = 200 mg/Kg
TCS (Total Corrosive Sulfur) = 157 mg/Kg (DBDS eq.)
CCD Test = corrosive
IFT = 19 mN/m
DBTP = 38 mg/Kg
Step 2
Failure in the 2013
Step 3
Post failure analysis in progress…
Step 4
Sea Marconi recommended the selective depolarization treatment (Chedcos) in order to remove the sulfur compounds (NOT DBDS) responsable for the corrosion.
