过电流倍数对多股铜导线故障的影响研究

Influence of Multiple Overcurrent on the Failure of Multi-strand Copper Conductors

利用警察大学自制电气故障模拟装置,使用水平放置的BVR 2.5 mm^2导线,研究多倍数过电流对其发生故障的影响。当多股铜导线发生过电流熔断现象时,会形成多种熔痕,根据熔痕形成过程中所参与的影响因素,可将熔断痕迹分为两类。导线绝缘未发生燃烧时的熔断痕迹形成环境较为单一,熔痕中α相呈现典型的一次枝晶形态,内部孔洞多而小。导线绝缘发生燃烧时的熔断痕迹形成于高浓度绝缘热解气体氛围中,同时还受火焰的热作用,影响因素较为复杂,除绝缘未发生燃烧时出现的共同特征外,电弧作用区熔痕会出现晶界开裂,股间熔痕出现珠串状孔洞现象。上述特征可作为认定过电流故障的可靠依据。

This paper studies the effect of multiple overcurrent on BVR 2.5 mm^2 wires horizontally placed by using an electrical fault simulation device made by the Police University. When multiple strands of copper wire are over-fused, various melting marks are formed. According to the influencing factors involved in the formation of the melting mark, the melting mark can be divided into two categories. When the wire insulation has not burned, the melting mark’s formation environment of the melting mark is relatively simple. The α phase in the melting mark presents a typical primary dendrite morphology with many small holes inside. When the wire insulation burns, the melting mark is formed in a high-concentration insulation pyrolysis gas atmosphere, and at the same time, it is also affected by the heat of the flame, and the influencing factors are more complicated. In addition to the common characteristics that occur when the insulation does not burn, grain boundary cracks in the arc-affected zone and bead-like holes in the inter-strand melting marks appear. These characteristics can be used as a reliable basis for identifying overcurrent faults.