BVR多芯铜导线过电流故障下燃烧及火焰传播研究*

为深入研究BVR多芯铜导线过电流故障下燃烧及火焰传播特征，采用堆栈技术分析导线受热形变，并利用高速摄像机记录故障导线发热、熔断及绝缘燃烧现象，研究导线发热形变、熔断时间及燃烧时火焰传播速度与电流值变化关系。结果表明:当I=136 A时，导线不发生熔断，只有当高温线芯直接接触周围可燃物才可引发火灾；当I=153 A时，导线会发生熔断现象，且熔断时间随过电流值升高而缩短；当I=204 A时，导线发生熔断，断路电弧引燃周围热解气体，火焰前沿迅速蔓延至导线两端，平均火焰前沿传播速度达2.2 m/s，平均明火持续时间达8.2 s，整根导线无需外界可燃物即可发生明火燃烧。研究结果可为起火原因认定提供技术指导。

Study on combustion and flame propagation of BVR multi-core copper wire under overcurrent fault

In order to study the flame propagation characteristics of the combustion engine under the overcurrent fault of the Bvr multi-core copper conductor,the stack technology is used to analyze the thermal deformation of the conductor,and the high-speed camera is used to record the phenomena of heating,melting and insulation burning of the fault conductor,the relationship between the current value and the heating,deformation,fuse-out time of the conductor and the flame speed during combustion is studied.The results showed that when I=136 A,the wire did not fuse,and the fire occurred only when the high-temperature core directly contacted the surrounding combustibles.When I=153 A,the wire would fuse,and the fusing time shortened with the increase of current value,reducing from 66 s at 153 A to 16 s at 238 A.When I=204 A,the wire would fuse,then the open-circuit arc after the fusing would ignite the surrounding pyrolytic gas and cause combustion.Meanwhile,the flame front would rapidly propagate to both ends of the wire with an average propagation speed of 2.2 m/s,the average duration of open flame reached 8.2 s,and the whole wire would occur the open flame combustion without requiring the external combustibles.The research results can provide technical guidance for determining the cause of fire in fire investigation.