| Timeline | 2014 |
| Project Overview | Real-time, hour-by-hour monitoring with the Serveron TM8 enabled early detection of a developing thermal fault in a transformer, preventing catastrophic failure. |
| Products | Qualitrol Serveron TM8 |
The Role of Oxygen Monitoring in Transformer Diagnostics: A Serveron TM8 Case Study
This is a Qualitrol Case Study. See the original article here
Background
In 2014, a U.S. utility was monitoring a 336 MVA, 500/230 kV auto-transformer that had been in service since 1979. Due to its history of gas formation, hydrocarbon gas levels had been consistently high, making it a prime candidate for continuous dissolved gas analysis (DGA) monitoring. A Qualitrol Serveron TM8 multi-gas DGA monitor was deployed to track gas concentration changes in real-time.
Early Warning and Escalation
On June 23, 2014, at 1:00 AM, the Serveron TM8 triggered an alarm due to a rapid increase in ethylene (C₂H₄) and methane (CH₄), both of which had been stable at elevated levels for several months. Over the next five days, operators closely monitored gas trends while keeping the transformer under load. When acetylene (C₂H₂) reached an actionable threshold of 10 ppm, they made the decision to take the transformer offline.
Diagnostic Insights and Root Cause Analysis
By analysing the load data, it became evident that the rise in gas production correlated with periods of heavy loading. Utilising Serveron TM View software, the Duval Triangle method indicated high-temperature overheating and localised hot spots within the transformer. These insights suggested the presence of thermal faults exceeding 700°C.
Subsequent internal inspection at a repair facility confirmed the presence of carbon deposits and insulation damage between the core and coil assembly and the tank. While the necessary repairs were made, the transformer continued to produce gas at a slow rate, leading to its planned decommissioning in the coming years.
Key Takeaways
This case study underscores the importance of real-time, online DGA monitoring. Unlike periodic lab-based DGA testing, which may miss sudden gas spikes, the Serveron TM8 provided operators with critical, hour-by-hour insights, allowing them to act before a catastrophic failure occurred. Despite its known gassing issues, the transformer was safely utilised as a backup asset thanks to continuous monitoring.