What does the presence of excessive Hydrogen in a DGA test typically indicate?

The presence of excessive hydrogen in a dissolved gas analysis (DGA) test typically indicates thermal breakdown of insulation. Hydrogen gas is produced as a result of overheating, which leads to the thermal decomposition of the insulation materials used in transformers. When temperatures rise significantly, typically above 140°C, insulation materials can start breaking down chemically, leading to the generation of hydrogen along with other gases like methane and ethylene.

High levels of hydrogen in the DGA results serve as a critical warning sign for potential issues within the transformer, suggesting that further investigation and possibly maintenance are needed to prevent more severe failures. In contrast, normal operation, loose connections, or moisture contamination would not specifically lead to excessive hydrogen generation, as these conditions would typically manifest through different gas signatures or levels in the analysis.