Post Arc Conductance Determination of a Spark Gap for DC Protection by UV Spectroscopy

A spark gap with fixed contacts was applied as a model setup for low voltage surge protection of DC currents. Therefore, the spark gap was combined with a parallel IGBT, resulting in a hybrid switching operation. The recovery behavior was investigated by spectroscopic methods. In earlier studies, we used optical emission spectroscopy in the visible spectral range to obtain plasma temperatures from atomic copper lines. Now, these results were extended by experiments considering the UV range. On the one hand, emission spectra of resonant atomic copper were taken. On the other hand, optical absorption spectroscopy of these lines revealed knowledge on the densities of atomic ground levels and hence, on the partition composition. It was found that the copper densities are too low to take significant influence on the conductivity of the remaining gas. Hence, the conductance could be determined based on air plasma composition and the temperatures obtained from OES.