Problem Solving - abnormally high level of acetylene
Fault Description
The customer reported that the annual Dissolved Gas Analysis (DGA) indicated an abnormally high level of acetylene (C₂H₂)
Fault Analysis
Reviewed the customer’s DGA report to assess the fault indicators. Based on the gas signature, the presence of C₂H₂ suggested possible arcing or thermal fault. Coordinated with the customer to schedule a planned outage for further inspection.
Site Activities and Findings
Oil Handling & Inspection
1) Drained the FR3 fluid from the transformer.
2) Removed the top cover for internal inspection.
3) During the inspection, it was discovered that the load break switch exhibited signs of prior arcing, and the bus conductor was physically damaged.
Corrective Actions Taken
1) Replaced the damaged load break switch assembly.
2) Reinstalled the top cover.
3) Filtered, degassed, and refilled the FR3 fluid into the transformer to restore dielectric integrity.
Electrical Testing
1) Conducted Winding Resistance Test (WRT), Transformer Turns Ratio (TTR), and Polarization Index (PI) testing to validate internal winding and insulation health.
2) Performed final (“as-left”) oil sampling for post-maintenance DGA and submitted it to the laboratory for analysis.
Recommendations & Coordination
• Engaged in follow-up discussion with both the customer and transformer manufacturer regarding proper operation procedures of the load break switch.
• Provided recommendations to the customer:
1) Ensure the load switch is never operated while the transformer is energized.
2) Establish a clear switching procedure and labeling to prevent future incidents.
