Comprehensive Analysis of Large Transformer Faults by Gas Chromatography

The use of gas chromatography to analyze and diagnose transformer faults involves taking oil samples from the operating transformer oil, separating and analyzing the gas dissolved in the oil, determining the components and content of the characteristic gas dissolved in the oil, and assessing the operating status and fault type of the transformer. Among all 32 preventive test items for transformers, the chromatographic analysis of dissolved gas in oil is prioritized first. Furthermore, the test items available for fault diagnosis are stipulated, and gas analysis in oil is also the primary choice for detecting abnormalities. Notably, among the six optional items for fault diagnosis, only the assessment of insulation moisture does not consider the analysis of dissolved gas in oil. This highlights the critical importance of chromatographic analysis of dissolved gas in oil in ensuring the safe operation and fault diagnosis of transformers.

In the diagnosis and detection of transformer faults, the composition and content of flammable characteristic gases in the oil are analyzed using gas chromatography. This method is increasingly valued and applied in power supply production due to its sensitivity and effectiveness. It can detect latent early faults during transformer operation, preventing transformer damage accidents, which is irreplaceable by current electrical test methods. This is because some faults do not cause qualitative changes in electrical characteristics until they develop to a certain extent, making them undetectable by standard electrical tests.

However, due to the complex sources of flammable characteristic gases in transformer oil, the gas chromatography method has certain limitations. These include difficulty in pinpointing the exact location or component of the fault, and the potential for misjudgment, leading to unnecessary maintenance. Therefore, the gas chromatography method must be combined with electrical test items for a comprehensive analysis and diagnosis to accurately identify faults qualitatively and quantitatively. This integrated approach is a requirement repeatedly emphasized in preventive test procedures.