Abstract: The ignition time, heat release rate, mass loss rate and combustion residue of ultra-high temperature fire-resistant cable under different external heat flux were analyzed via the cone calorimeter test. The results show that with the increase of external heat flux, the ignition time of cables is gradually shortened, the heat release rate and mass loss rate are gradually increased, so does the fire risk. The fire performance indexes of fire-resistant cables at the external heat flux of 35 and 50 kW/m2 increased by 44.4% and 176.5%, respectively, and the fire growth indexes increased by 30.4% and 83.0%, respectively, compared to those of 25 kW/m2. Combined with theoretical analysis, it can be concluded that the fire-resistant cable has the critical heat flux of 3.61 kW/m2 and average limiting heat release rate of 36.5 kW/m2, showing a low fire risk.

Key words: ultra-high temperature fire-resistant cable, cone calorimeter, heat release rate, time to ignition, fire risk