The DGA interpretation method using relative content of characteristic gases and gas-ratio combinations for fault diagnosis of oil-immersed power transformers

Dissolved Gas-in-oil Analysis (DGA) is used widely in the power laboratory and industrial field as a sensitive and reliable technique for the detection of potential incipient fault condition within oil-immersed power transformers. However, there is still no universally accepted interpretation method for DGA data. IEC 60599 and IEEE C57.104 standards provide some methods for the interpretation of DGA data, but DGA interpretation is not an easy task since DGA methods often cannot provide a diagnosis, will give a wrong diagnosis or unresolved the fault code. So, we analyzed seven gas components (hydrogen, methane, acetylene, ethylene, ethane, carbon monoxide and carbon dioxide) and ten gas ratio combinations. Then, we reorganized and analyzed the four relative proportions of four combustible gases (hydrogen, methane, ethylene, and acetylene) and the six gas-ratio combinations (R1, R2, R3, R5, R6 and R10). We used above conclusion to propose the new method for fault diagnosis. Finally, we selected some fault cases from reference to verify the proposed method. The result shows that the proposed method has better performance and higher accuracy than conventional methods and can be able to classify fault.