铜包铝导线过电流发热现象及宏观痕迹研究

Study on excessive current heating and macroscopic trace of copper-clad aluminum conductor

为研究多股铜包铝导线在过电流故障下的痕迹特征,选用符合国家标准的铜包铝导线,通过改变预设电流值大小,制备不同程度过电流下的铜包铝导线熔痕,观察导线受热后的发热现象以及宏观痕迹特征。分析发现:导线发热变形的现象与电流值有关,只有过电流倍数在2~4倍之间时能引起绝缘大范围燃烧从而引发火灾;并且过电流铜包铝导线有且仅有在第一断点处产生熔珠,由于火烧熔痕不产生熔珠,因此在火场中一旦发现熔珠,就一定发生了短路或者过电流故障。

In order to study the trace characteristics of multi-strand copper-clad aluminum conductor under the fault of over-current, copper-clad aluminum conductor conforming to the national standard was selected. By changing the preset current value,melting marks of copper-clad aluminum conductor at different degrees of over-current were prepared to observe the heating phenomenon and macroscopic trace characteristics of the conductor after heating. The analysis shows that the phenomenon of wire heating deformation is related to the current value,Only when the over-current multiple is between 2 and 4 times,the insulation can be burned in a large range,which can cause fire;in addition,the copper clad aluminum conductor with excessive current has and only produces molten beads at the first breakpoint. Since molten beads do not appear in the burn mark,short circuit or over-current fault will occur once molten beads are found in the fire.