Gas Generation and Pressure Characteristics of Arcing Faults in Transformer Oil

In recent decades, tank explosions caused by arcing faults in oil-immersed transformers have been of great concern. Due to the high safety risks and testing difficulties, the complex factors affecting the pressure characteristics of arcing faults have been difficult to analyze comprehensively. This paper established an experimental platform for arcing faults in transformer oil and investigated the gas generation and pressure characteristics of arcing faults under different electrode gaps. The length of the arc channel changes considerably during an arcing fault, which brings about an increase in pressure, and the probability of this phenomenon's occurrence increases with the electrode gap increase. The increase in the electrode gap increases the arc voltage and thus the arc energy on the one hand, and on the other hand increases the quantity of generated gas per kJ of energy which is about 0.0005 L/(kJ·mm) under the experimental conditions in this paper, so the dual effect leads to a significant increase in pressure. In addition, based on the experiments, a bubble-fluid-structure coupling model is proposed which considers the change of bubble temperature. A sufficient comparison between the experiments and the simulations shows that the model can accurately describe the dynamic behavior of pressure by arcing faults.