| Timeline | 2017 |
| Project Overview | Qualitrol Serveron TM8 device detected an unexpected rise in oxygen levels in a 30+ year-old transformer, highlighting the importance of continuous monitoring for operational anomalies. |
| 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
Aging transformers require continuous monitoring to ensure reliability, especially those operating under nitrogen-blanketed conditions. In November 2017, a Qualitrol Serveron TM8 multi-gas dissolved gas analysis (DGA) device was actively monitoring a 30+ year-old 3-phase 230kV shell-form Generator Step-Up (GSU) transformer. For a prolonged period, oxygen (O₂) levels remained steady at 130 ppm. However, on November 16, 2017, the TM8 triggered an alarm as oxygen levels began to rise unexpectedly.
Unexpected Oxygen Surge and Investigation
Over the next three days, the transformer’s oxygen concentration climbed dramatically, peaking at 2,150 ppm before gradually stabilising at 200 ppm. This fluctuation raised concerns, prompting a detailed review using Serveron TM View software. Despite the significant oxygen increase, no traditional fault indicators were detected using established DGA diagnostic methods.
Importance of Oxygen Monitoring
The sudden spike in oxygen levels suggested an operational anomaly rather than an internal electrical fault. In nitrogen-blanketed transformers, changes in oxygen concentration can indicate issues such as leaks, improper sealing, or gas ingress through the blanket system. While conventional fault diagnostics did not flag an issue, the oxygen fluctuation provided valuable insights into potential maintenance needs, reinforcing the necessity of multi-gas DGA monitoring.
Conclusion
This case study highlights the critical role of oxygen measurement in transformer diagnostics. While traditional DGA parameters focus on combustible gases, monitoring oxygen variations offers additional insights into operational health, enabling proactive maintenance and preventing unforeseen failures. The Serveron TM8’s real-time detection capabilities again demonstrated their value in transformer asset management.