Abstract: In order to prevent overload and further thermal disaster due to inadequate core cross-sectional areas to current load' demands, based on radial layered material distribution structure of high voltage cable, the coupling mechanism of the heat generation of the core inside the cable, the heat conduction of the interlayer and the heat dissipation of the outer layer was explored. For the same cable, by keeping the core section and outer layer structure unchanged, the temperature evolution of the cable both inside and outside in different cases of overload triggered by different current intensities was analyzed. The human factors causing the overheat of core were also analyzed, including some unscrupulous manufacturers maliciously reducing the core section. And the effects of both the condition of surface convection heat dissipation and the core type on the overload overheating behavior were discussed. The results show that both extremely thin cable core and thick outer layer materials will lead to significantly increased temperature of the cable both inside and outside, which easily causes the thermal disaster, and that compared with the copper core cable, the aluminum core cable generates heat more efficiently, thus it is more likely to cause a thermal disaster in a poor ventilation and heat dissipation environment.

Key words: overheat, cable fire, core, heating model, buried laying, temperature