The Influence of arc on Dissolved Gases in Transformer Oils

Transformer is one of the most important apparatuses in a power system. During operation electric arc may take place in a power transformer. The electric arc may degrade the oil insulation and enhance the dissolved gases in the oil. Recently, dissolved gas analysis (DGA) is widely used in diagnostics of the transformer condition. This paper reports the experimental results on the effects of arc on the dissolved gas in transformer oils. The samples used were several products of transformer oils. The samples were subjected to arc produced at needle tips under AC voltage. The parameters used in the experiments were applied voltage and duration. The experimental results showed that the application of arc in transformer oils increased the concentration of combustible gases such as hydrogen, ethane, ethylene and acetylene. Key gases, Roger´s ratio and Duval Triangle methods indicated similar results of arcing and overheating