Melt dripping behavior in the process of flame spread over energized electrical wire at different pressures

摘要

Melt dripping of polymer insulation in electrical wires is impacted by some factors, such as ambient pressure and electric current. The motivation of this paper is to investigate and discuss the effect of these factors on melt dripping characteristics in the process of flame spread over electrical wire. The results show that the number of dripping times and dripping frequency generally increase with ambient pressure reduced. No dripping phenomenon occurs when the ambient pressure is below 40 kPa at any electric current or is above 70 kPa without electric current applied. There is a good parabolic correlation between the ambient pressure and dripping frequency. The equilibrium temperature of conductor resulted by electric current increases with electric current. A critical electric current found to divide the temperature rate into two regimes is about 8 A. The dripping period and dripping frequency depend on the electric current. The dripping frequency fits well with electric current using a power-law function. The numerical data are consistent with the experimental data. Besides, the decrease in dripping frequency is greater with ambient pressure at reduced electric current, whereas at larger electric current, the electric current, rather than the ambient pressure, dominates the increased dripping frequency.