Pressure rise calculation during short circuit fault in a closed container based on arc energy equivalent method

摘要

When the fault Arc inside the medium-voltage (MV) metal enclosed switchgear happens, the arc heats the filling gas in the switchgear, resulting in pressure rise, which may seriously damage the electrical equipment and building and may even endanger personnel. In order to put forward an appropriate calculation method to calculate the pressure effect caused by the internal arc in the MV switchgear with larger size and complicated structure, the arcing characteristic was introduced and an indirect multi-physics coupling analysis method based on CFD has been put forward. The simulation and test models with a small size were established, and the internal pressure rise was calculated under different arc sizes and the surface areas of pressure relief opening. The results show that, when using the indirect coupling analysis method, the relative error of average pressure between test and simulation calculation is just about 2%. The size of arc has no effect on the pressure distribution, but large influence on the temperature distribution. The change of pressure distribution in the simulation switchgear is bigger than temperature before and after the pressure relief disc opens. Hence, in order to simplify the calculation, the pressure distribution caused by internal arc in the MV switchgear obtained by the indirect coupling analysis method is feasible.