单股铜导线过电流故障痕迹形成规律研究

Study on Formation Mechanism of Overcurrent Solid Copper Conductor Effects

根据过电流故障发生机理,视频截帧分析各种过电流值条件下导线的发热过程,用金相分析研究痕迹特征,研究发现:过电流值升高,导线发生熔断,产生断路电弧,熔断痕外观上与火烧熔痕类似;5~7I_e时,导线中部易形成玫瑰刺状结疤痕,5.5I_e时最为显著;过电流熔痕的组织以树枝晶为主,具有明显的方向性,几乎没孔洞。研究可为提取和认定过电流故障痕迹提供技术支持。

On the basis of overcurrent causes, a study has been conducted to analyze the heating process of overcur- rent conductors at different amperes by observing every frame of the overcurrent video and study the trace characteris- tics of metallurgical structure of overcurrent conductor effects. The results show that if the current flowing through the conductor increases, the conductor will break apart, forming a fuse arc; the fuse breaking trace is similar to the melting trace caused by fire; When the current is between 5 and 7Ie , a scab pattern in rose thorn shape will be formed, when the current is 5.5Ie , this scab pattern can be seen vividly. The overcurrent breaking trace consists of dendrites with obvious direction but no hole. This study can assist fire investigators in finding and identifying over- current trace.