Studies of Power Arc Faulta in SF6 Insulated Equipment

Power arc behaviour in gas insulated equipment and the influence of arc motion on damage resulting from simulated faults were investigated in the laboratory. Experiments were carried out with power-frequency currents up to 22 kA in a co-axial test chamber insulated with pressurized SF6 and air. Arc motion was measured with time-of-flight and infrared thermal imagery techniques for various fault currents, geometries and pressures. A linear, relationship between the axial arc velocity and fault current was established. For a typical 138 kV SF6 bus duct, this velocity is 100 cm/s·kA. The influence of spacers on the motion of arcs in the gas insulated equipment was studied with respect to temperature rise of and damage to the sheath