Temperature distribution in ablation controlled switching arcs using optical emission spectroscopy

Ablation from polymeric casing materials has a pivotal role in switching devices. The ablated gases influence the arc properties and assist the arc movement during current interruption. In this study, spatially resolved optical emission spectroscopy is used to determine the temperature distribution across a switching arc. A simplified setup is built to mimic the conditions found in low voltage switching devices. The quantification of the temperature variations due to the interactions between an arc and ablated vapors from the polymeric walls are aimed in this work. As a marker for temperature, atomic and ionic lines of copper are used. The copper spectral radiance is simulated using ad-hoc temperature profiles. The temperature profiles used to simulate the spectra are adapted until the simulated spectra match with the ones obtained experimentally. This method works well in the copper dominated core region of the arcs. In proximity of polymeric walls, it is of limited use due to the low temperatures and concentration of copper. In addition, C2 molecular emission close to the walls overlaps with the copper lines. The inferred temperatures are then employed to assess the cooling effect of different polymeric materials in function of current and geometry.