Scenario
Thermal power plant with 8 GSU transformers
Nameplate data of the transformer:
Manufact: xxx
Power [MVA]: 370
Voltage [KV]: 400
Oil mass [Kg]: 58.000
Oil type: blended oil
The analysis and diagnosis of the 2011 showed:
Total sulfur = 5700 mg/Kg
TCS (Total Corrosive Sulfur) = 104 mg/Kg (DBDS eq.)
CCD Test = corrosive
DBTP (dibenzothiophene) = 42 mg/Kg
Step 2
August 2011: failure with explosion and fire
Solution
Diagnosis, prognosis, with a recommendation to perform the selective depolarisation treatment (Chedcos) for the removal of sulfur compounds (NOT DBDS) responsible for the corrosion.
