Behaviour of silicon ointment for power-cable insulation under external heating

Abstract

The burning process and typical fire parameters of power-cable silicon ointment were explored experimentally using a cone calorimeter, and the effects of the external radiation heat flux (ERHF) and pool size were examined. The results showed that a shell with the appearance of numerous white convex particles was formed on the fuel surface soon after ignition and prevented the burning of the silicon ointment. These convex particles swelled with time, and the shell cracked under the influences of the ERHF and combustible gas release. The ERHF significantly affected the heat release rate (HRR) of the silicon ointment. Under low and high ERHFs, the HRR curve of the silicon ointment exhibited three and four stages, respectively. The peak HRR increased with the ERHF, and the influence of the pool size on the HRR of the silicon ointment was complex. The CO production rate of the silicon ointment increased continuously throughout the duration of the fire. The effect of the ERHF on the CO production rate was not significant. The CO production rate initially increased with the pool size but decreased when the pool size reached 9.5 cm.