Experimental investigation of the effects of current and voltage on the thermal characteristics of low-voltage DC fault arc

Abstract

Fault arc is one of the potential causes of electrical fires. To predict the thermal characteristics of long-duration fault arcs in low-voltage DC systems, this study conducted a series of fault arc experiments under different initial current and power supply voltage conditions. The results indicate that the arc ignition process for the copper-copper electrodes follows the sequence: break arc, arc heating electrode, electrode melting, and arc extinction. The melting and dripping speed of the copper electrode tip is influenced by arc power, and in some high-power arc cases, heat transfer to the electrode does not reach a stable state before arc extinction, thus the electrode temperature does not always scale with arc power. By analyzing the arc power and arc duration based on the volt-ampere characteristics of the arc and its heat transfer characteristics to the electrodes, it was found that while an increase in initial current and power supply voltage enhances arc power, it also accelerates electrode consumption, thereby shortening the arc duration. The combined application of the arc power model and arc duration model established in this study enables effective prediction of arc energy. The research findings provide guidance for fault arc prevention in low-voltage DC electrical systems.