Abstract:

In order to accurately study the phenomena of core heating and insulation burning of copper- clad aluminum wire under different overcurrent conditions. Taking 2.5 mm2 PVC multi- strand copper-clad aluminum wire as the research object, the over current faults of 40, 50, 60, 70, 80 A were simulated respectively, the changes of core heating, fusing, arc ignition and insulation burning of overcurrent conductor with current value were studied by using high-speed image and video analysis technology. The results show that when the over current value is less than 40 A, only the core of the wire is heated and the insulation is pyrolyzed and fumed, the core is not blown. When the over current value is greater than 50 A, the heating of the wire core is intensified and the fusing time is getting shorter and shorter from the average of 120.8 s in 50 A to 19.8 s in 80 A. When I=50 A, the arc ignites the pyrolytic gas around which forms combustion within the maximum range of 8.4 cm. When I≥60 A, the flame ignited by the arc will spread to the left and right ends of the conductor, but the flame spreading rate will first accelerate and then slow down with the increase of current value, it will be the fastest at 70 A with an average of 7.13 m/s. 

Key words:  electrical fire, overcurrent fault, copper clad aluminum wire, core heating, insulating combustion