铝合金导线过电流发热过程及痕迹特征

Fire patterns and heating process of the AA8030 aluminum alloy wire getting overcurrent

模拟AA8030型导线过电流故障,研究导线通过不同倍率额定电流时的发热过程,借助高速影像分析导线发生整体燃烧的原因,分类统计断点痕迹的数量、位置和典型特征。研究表明:当I≥3Ie时,导线出现断路,产生断路电弧,形成电弧熔断痕迹;I≥4Ie时,还会产生导线锯齿状折断痕迹,火场中可通过综合分析这两种痕迹,认定该型导线发生了较大电流的过电流故障;当I≥5Ie时,导线断路电弧引燃预混热分解气体层,形成整根导线的燃烧,这使得导线火灾危险性更大。

The overcurrent fault of AA8030 aluminum alloy wire was simulated.Heating process of the wire under different ratio of rated current was studied.By high speed camera,cause of the wire integral combustion was analyzed,and the number,location and feature of power failure traces were classified and counted.Study showed that,when I≥3 Ie,open circuit happens with breaking arc,and has beads on the end;When I≥4 Ie,globules like saw teeth was produced;in fire scene,it can be determined that the overcurrent have occurred in the conductor through considering and observing those beads and globules;When I≥5 Ie,insulation materials would be decomposed into gas,and the brief parting arc can ignite flammable gases,causing the combustion of the whole wire,which is more serious for ignitibility.