Experimental research on the thermal characteristic of low-voltage alternating current (AC) arc faults

The objective of this paper is to study the thermal characteristic of low-voltage alternating current (AC) arc faults. Two series of experiments were designed, including polyvinyl chloride (PVC) wire ignitions experiments and electrode arcing experiments (non-ignitions) subjected to arc faults at different effective currents. The ignition time of the wire and the temperature of the electrode were investigated to characterize the arcing hazard. Results show that the ignition time of the wire decreases with the increasing arc current, and the wire with a larger cross-section area requires more time to be ignited at the same current. For non-ignition experi- ments, the electrode temperature increases first and then varies little. A heat equilibrium stage can be reached, where the heat transfer of the arc to the electrode is equal to the heat dissipation of the electrode. Furthermore, a heat transfer model for the arc fault is established to obtain the electrode temperature. The temperature of the arc-electrode interface is used to characterize the arc energy, and it is found the temperature showed a loga- rithmic increase with the current. The results of this study may be useful in the safety design of electrical wires, and can be exploited as hazard indicators for the risk assessment of electrical fires.