Coupled Calculation Method for Pressure Generation and Relief Caused by Arc Discharge in Transformer Oil

The electric arc caused by insulation failure inside a transformer oil tank can lead to the decomposition of insulating oil, resulting in the generation of gas and an increase in internal pressure, which may trigger an explosive combustion accident. To prevent excessive pressure rising in the tank, pressure relief valves (PRV), rupture disc, and other devices are typically installed on the tank for pressure release. However, the coupling mechanism between the pressure generation during arc discharge and the release devices remains inadequately assessed in a quantitative manner, making it challenging to perform effective explosion-proof design for the pressure relief device (PRD). This paper explores the coupling relationship between the release flow rate of devices such as the conservator tank, PRV, rupture disc and pressure generation process, using the flow rate as a coupling variable. A coupling algorithm is developed to describe the interaction between pressure generation and release. The coupling algorithm was validated using both two interconnected tanks experiment and the 1/16-scale Ultra-High-Voltage（UHV）transformer tank experiments. Finally, the discharge performance of PRVs with different flow capacities was evaluated for application in UHV transformer tanks. This study provides tools for the explosion-proof pressure relief design of transformer oil tanks.