Hazard Effects and Mechanism of Thermo-electrical Synergistic Aging in Mining Polyethylene-insulated Conductors

Electrical fires caused by cable degradation constitute a critical ignition source for gas and dust explosions in underground mining environments, where aged cable insulation serves as the primary contributing factor. Under harsh mining conditions, characterized by elevated ambient temperatures and high operating voltages, electrical cables experience accelerated electrothermal aging due to synergistic temperature-voltage degradation mechanisms. However, existing studies have primarily concentrated on investigating the influence of individual stress factors on cable fire behavior. To address this research gap, this study developed an electro-thermal synergistic aging platform and conducted comparative investigations of flame propagation characteristics and thermal stability for two different-sized polyethylene(PE) wires using flame spread tests and simultaneous thermal analysis(TG-DSC), under both electro-thermal synergistic aging and pure thermal aging conditions. The results demonstrate that electro-thermal synergistic aging, compared to thermal aging alone, reduces the flame spread rate and mass loss rate to 91% and 71%, respectively, while significantly increasing molten dripping frequency. Furthermore, the insulation layer exhibits an earlier melting peak, a delayed decomposition peak, and more substantial increases in residual carbon content. These findings elucidate the synergistic effects of electrical and thermal stresses on the combustion and pyrolysis behavior of PE wire, offering valuable theoretical insights for fire risk assessment and prevention in underground mining electrical systems.