Complementary Experimental and Simulation-based Characterization of Transient Arcs

Electric arcs generated by transient lightning-type surge currents in protection devices for low voltage appliances are studied by optical emission spectroscopy and spectra simulations. A surge pulse amplitude of 5kA and 8/20µs shape are applied. The arc radiation is recorded by a 3/4m spectrometer and a high-speed camera equipped with metal interference filters for the O I (777nm) and Hα (656nm) lines. Absolute calibration was realized using a tungsten strip lamp. The arc images indicate a non-symmetrical shape. To determine the plasma properties, accompanying simulation solving the equation of radiative transfer for a given pressure and a temperature profile was carried out assuming local thermodynamic equilibrium. Line broadening due to the Stark effect is taken into account. The computed and measured spectra are compared. The conditions are varied until the measured and computed spectra match.