Contribution to the assessment of the power balance at the electrodes of an electric arc in air

Abstract

The aim of this paper is to improve our knowledge concerning the power balance at the electrode surfaces in the case of an electric arc of short duration with a small electrode gap burning in air at atmospheric pressure.With this aim in view, we propose a simple method using the experimental results obtained through the observation of the tracks left by the arc and a numerical simulation of the thermal phenomena occurring in the electrode during the arc heating.This method, based on the analysis of the compatibility between experimental results and modelling results, allows us to assess a zone of possible values for the main parameters of the arc root (power and surface power density brought by the arc to the electrodes). A simple usual volt equivalent approach of the power balance is proposed. Calculations and experiments have been conducted for several copper anodes and cathodes. The values for the volt equivalent at the anode are found in the range 9–12.6 V, for the cathode 5.4–9 V. The values for the surface power density are found to be near 6.5 × 109 W m−2 at the cathode and 6 × 109 W m−2 for the anode.