Experimental Study on Thermal Characteristics of DC Arc Formation between Ice-Electrode Gap

The partial arc is a destructive discharge phenomenon for HVDC insulators under icing conditions, leading to flashover incidents. This study sets up a calibrated Schlieren system to examine the DC arc's thermal characteristics on an ice surface. The theoretical analysis shows that the plasma component changes significantly between 2000 K to 2882 K, which is the characteristic temperature of arc formation. Experimental results show that the temperature characteristics in the time domain depend on the discharge stages. A temperature jump appears at the spark discharge and then increases exponentially with the leakage current during the arc formation. However, the temperature in the corona and brush discharge is almost unchanged. Results also show that higher water conductivities increase the spark temperature and promote arc formation, but do not affect corona and brush discharge, which take place in the air gap. In the arc channel, the gas near the core comprises molecules, atoms, electrons, and ions, while the gas in other regions is mainly composed of neutral molecules. This study provides findings that might enhance our basic understanding of the ice surface's partial arc formation process.