A TDCG value of 1,201 - 2,500 ppm indicates what condition?

A TDCG value, or Total Dissolved Combustible Gases value, of 1,201 - 2,500 ppm generally indicates a condition of decomposition occurring within the insulating oil of a transformer. This increased concentration of dissolved gases can be associated with thermal or electrical faults within the transformer, such as overheating or arcing, leading to the breakdown of the oil and the production of gases as a result of the decomposition of the insulating materials.

In diagnostic practices related to transformer maintenance, monitoring TDCG levels is critical for early detection of potential issues. Values above 1,200 ppm suggest that the breakdown products from insulation, typically gases like hydrogen, methane, and ethylene, are present in significant amounts. This range signals that not only is there some level of distress in the transformer’s operation, but that it warrants further inspection or corrective action before it leads to more severe issues or failures.

Conditions such as normal operation would typically reflect much lower TDCG values, indicating no thermal decomposition or electrical faults. Similarly, contamination and stability would be associated with different gas levels and conditions that are not characterized by significant decomposition. Thus, this understanding emphasizes the importance of careful monitoring and analysis of gas levels to proactively manage transformer health and prevent catastrophic