Parameters' Values of Small Signal Equivalent Circuit of Electric Arc Gaps in DC Networks

The currently increasing significance of DC application from low voltage level to high voltage level directly goes along with the problems of DC electric arcs. This is valid for both electric arcs within mechanical switchgear and fault arcs at random spots within electric networks. Therefore in modeling of DC networks appropriate models of electric arcs are essential. After a brief issue-related theory of electric arcs a summarizing classification of arc models is outlined in this paper to show the wide variety. Here, the focus is on a special type of arc model assigned to the class of equivalent circuit models that describes the dynamic small signal terminal behavior of a DC electric arc in one specific operating point. The operating point selection is done on the basis of the static arc characteristics. By the use of impedance spectroscopy both an appropriate small signal equivalent circuit model and the values of its parameter are determined for one exemplary operating point. Therefore in this paper an experimental setup is presented by which the static arc characteristics for variable arc length are measured as well as the impedance spectroscopy experiment is performed. The operating mode of the experimental setup is altered between the measurement of the static arc characteristics and the small signal analysis. As a result a small signal equivalent circuit model and an exemplary set of its parameters' values for a small signal equivalent circuit of arc gaps in low voltage DC networks is presented.