The Calculation of Overpressure in Metal-Enclosed Switchgear Due to Internal Arcing

The mechanical stress of metal-enclosed switchgear installations due to fault arcs can be predicted by means of pressure calculation. In this paper a number of calculation methods is discussed. The results of pressure calculation are compared with pressure measurements performed in model switchgear cubicles. It is shown, that simplifying assumptions in some calculation methods lead to inaccurate results. Pressure calculation for switchgear cubicles with effective pressure relief openings should take into account the spatial limitation of arc energy input.