Analysis of Dispersive Characteristics and Structures of Copper Wire Melted by Overcurrent

In order to study the characteristics of copper wire according to the variation of fusing current, melting process of wire has been analyzed and the analysis of structure has been performed. Melting process was taken with HSIS (High Speed Imaging System) at a rate of 500 frames per second. A flash of light was seen at the center of the wire during melting process and a lot of small beads were scattered from the center to the outside of the wire. In the analysis of metallurgical structure, small dots grew into dendrite structure by overcurrent. Dendrite structure appeared in case that the values of current increase rate are lower than 2.5[A/sec], and the structure grew more according to the larger fusing time. Therefore, the growth of dendrite structure was related to the fusing time (current increase rate per time). The shorter the fusing time was, the narrower the melted areas were. SEM (Scanning Electron Microscope) and EDX (Energy Dispersive X-ray Spectrometer) analysis showed that oxygen is included in black dots of dendrite structure. An empirical equation was derived based on the experiments of fusing current, and the relationship among Preece, Onderdonk and the empirical equation was analyzed. The results will be applicable to the cause analysis of electrical fire because fusing time and fusing current can be calculated through the metallurgical analysis.