Temperature and composition of AC arc plasma of medium voltage distribution networks in the air

Abstract

AC electric air arcs in medium voltage (MV) distribution networks, including railway catenary, photovoltaic power generation systems, and traditional distribution networks, can cause insulation damage accidents. Although various studies have been performed on the macroscopic characteristics of the MV AC arc in the air, the research on the physical properties of the arc, such as temperature field and particle composition, is relatively lacking. This work deals with diagnosing the temperature and particle composition of the arc under laboratory conditions based on the arc generation and the moiré deflection diagnosis systems. Based on the experimental results, there are three typical stages in developing the MV AC arc: the initial, transition, and stable combustion. The temperature during the stable combustion of the arc is between 1500 and 2100 K, while the fluctuation period is half a power frequency cycle. The particle components of the arc are mainly composed of O2, N2, and O. Different from the DC arc, the AC arc exhibits a zero-crossing extinguishing phenomenon, while the gap temperature is still high after extinguishing the arc, and the insulation has not been fully restored. This research provides a method for diagnosing MV AC arcs in the air under laboratory conditions and initial values for the arc modeling.