Approach of Voltage Characteristics Modeling for Medium-Low-Voltage Arc Fault in Short Gaps

With the emergence of dense power due to the use of relatively low-voltage infrastructures, which are becoming more common in distribution networks, the risks related to low-voltage arc flash are drawing more attention. Arc voltage, as the critical factor in arc flash mitigation, is strongly related to the determination of insulation distance and re-striking voltage level. However, while much attention has focused on the need for hazards calculation and the selection of appropriate personal protective equipment, the physical characteristics of arc has received relatively little attention. Although some related researches have been carried out in high-voltage arc faults with long gaps, the medium-low arc faults, which have more dynamic nature, is rarely to be investigated. To comprehensively analyze the voltage characteristics of medium-low-voltage arc fault in short gaps, this paper discussed the mathematical approach for arc voltage modeling. To achieve the reliable model parameters, the magnetohydrodynamic simulation method is explored as the amendment for mathematical model. Moreover, in order to have an easy application for on-site practice, a concisely alternative model for arc voltage gradient calculation is developed. The fitting result shows the model has a good ability to accurately estimate the voltage gradient of medium-low-voltage short arc.