Measurements of Thermal Radiation Brightness of Anode Surface After Current Zero for a Range of Current Levels

Overheating of electrode surfaces during arc burning is considered to be the main reason of a breakdown after kiloampere arc extinction. The greatest interest in this connection is the most energy-loaded electrode-the anode. The aim of this paper is to measure the distributions of thermal radiation brightness of anode surface just after current zero for a range of arc currents from successfully interrupted levels up to the levels of guaranteed failure. The measurements allow us to determine the anode surface temperature distributions and trace the anode cooling. The measurements were done by a high-speed video camera Phantom M310 equipped with a Carl Zeiss 100/2 macro lens. The anode surface temperature distribution was obtained by comparison of the results of anode surface filming and the results of calibrated band-lamp filming in identical conditions. The measurements were done for CuCr 70/30 electrodes with a diameter of 64 mm generating axial magnetic field for the currents up to the interruption limit. The cooling was traced over the time interval, during which the absolute majority of breakdowns takes place at the TRV application for the given contact system.