Electrode‐fall voltages of SF6 and air arcs between electrodes of Fe, W, Cu‐W, Cu and Ti in the current range from 10 A to 20 kA

Abstract

AbstractMeasurements were made of the sum of cathode‐fall and anode‐fall voltages, i .e. electrode‐fall voltage Ufall for SF6 and air arcs at a pressure of 0. 1 MPa in a wide current range from 10 A to 20 kA. The arcs were burned between electrodes of iron, tungsten, copper‐tungsten, copper and titanium. For each electrode, Ufall atagiven current was estimated as the arc voltage at the zero gap length between the electrodes, which was extrapolated from arc voltages measured in short gaps with lengths below 3 mm. The electrode‐fall voltage Ufall of the SF6 arc proved to be 17.5 V, 13.8 V, 17.5 V, 17.5 V and 17.3 V for the Fe, W, Cu‐W, Cu and Ti electrodes, respectively. The electrode‐fall voltage Ufall was affected by the electrode material, while Ufa u of the air arc is almost the same as that of the SF6 arc. It was also found that Ufall of each arc at a given electrode was independent of current in the above range.