Reduction risk: criteria for choosing an appropriate design approach [for switchgear]

The effects of the switchgear arc are strongly depending on three main factors: the fault current level; the available free space surrounding the switchgear; and the construction of the switchgear. If the fault currents are small enough, as in the case of overhead lines, the arc energy can be handled by the housing of the switch and the arc can be kept inside the housing. Also the free space in these applications is not limited because the switch is normally located about 5 to 10 m above the operator. In this case, it is enough, if hot gases are not directly downwards in direction. In this paper, the switchgear short-circuit currents are shown depending on the distance from the feeding transformer with different power line cross-section and different line voltages