Experimental Study on Overcurrent-induced Short-circuit Fire of RVVB Wires and Characteristics of Slashing Melted Beads
In order to study the process of overcurrent-induced short-circuit failure of RVVB wire and the typical characteristics of splashing melted beads,a 220 V overcurrent-induced short-circuit failure apparatus was built.The short-circuit process was analyzed with the initial short-circuit time and arc duration recorded by video imaging technology.The splashing melted beads were collected to analyze their morphological and typical organizational characteristics.The results show that when the wire is heated from the inside to the outside,the PVC insulation is gradually carbonized to failure,and there is an exponentially decreasing relationship between the initial short-circuit time and the current value of the wire.According to the different morphology,the splashing melted beads can be divided into spherical beads,connected spherical beads,cratered beads,semi-spherical beads,connected semi-spherical beads,connected rods and beads with points connected,and the metallographic organization can be divided into four categories.The results can provide some help for identifying the causes of failures.
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