Der freibrennende Störlichtbogen

Long high current arcs (I ? 60 kA, f = 50 Hz, t ? 200 ms, l = 1 m) appear after discharges at electric power systems. The arc must be localized in a separate volume in order to protect the equipment from the high temperature. The arc is stabilizing by the plasma-beam starting at its bottom. The properties of the plasma-beam are described: general phenomena, the length as a function of current and time, the behaviour in a half-cycle and the acoustic emission. Several conclusions for the construction of the protective armatures are presented.