Radiation power of SF6 arc in current range from 500 to 20 000 A at pressures of 0.1 and 0.4 MPa

Radiation power of a SF6 arc was investigated at pressures of 0.1 and 0.4 MPa over a wide current range from 500 to 20 000 A. Theoretical investigation revealed that the SF6 arc dissipates power radiated at wavelengths above 200 nm as a radiation loss and that the radiation has very much higher power in a wavelength range from 200 to 1800 nm than at wavelengths above 1800 nm. On the basis of these results, an observation equipment was constructed of four photodiodes having different spectral sensitivities to measure the total radiation power integrated over the wavelength range 200–1800 nm. Experiments were made to measure the radiation power of an SF6 arc between electrodes with a gap length of 15 mm. The radiation power of the SF6 arc was found to increase from 2.4 to 200 kW with a current from 500 to 20 000 A at a pressure of 0.1 MPa. Increase in the gas pressure from 0.1 to 0.4 MPa caused the radiation power to rise by a factor of 1.7 and 3.4 at currents of 500 A and 10 000 A, respectively. The radiation power accounted for about 15% of the power input into the arc column at a pressure of 0.1 MPa, almost regardless of the arc current. This fraction grew to 30–40% as the gas pressure increased to 0.4 MPa.