高压电缆过载运行条件下内外温度场演化特性

Study on inner and outer temperature distribution of high-voltage power cable being overloaded

为预防高压电力电缆运行中,因线芯横截面面积不满足电流载荷要求形成过载,而发生热灾害事故,基于高压电缆径向层状材料分布结构,探究电缆内部线芯生热、中间层导热与外表层散热耦合机制;对同一电缆,保持线芯截面与外层结构不变,分析不同电流强度导致其过载时,电缆内外温度场演化特征;针对不法厂商恶意缩小线芯截面的行为,分析该"人为过载"因素引起的线芯过热危险性,并讨论表面对流散热条件、线芯种类等因素对该过载过热行为的影响。结果表明:电缆线芯过细、外层材料增厚导致电缆内外温度显著增高,易引发热灾害事故;与铜芯电缆相比,铝芯电缆发热更显著,在通风散热不良环境中,更易引发热灾害事故。

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.