Dynamics of glowing contacts triggered by poor electrical contact
ZHANG Jing1, CHEN Tao1, HUANG Lida1, SU Guofeng1,2, SUN Zhanhui1, CHEN Jianguo1
1. Institute of Public Safety Research, Department of Engineering Physics, Tsinghua University, Beijing 100084, China; 2. Hefei Institute for Public Safety Research, Tsinghua University, Hefei 230601, China
Abstract：Glowing contacts triggered by poor electrical contact are one of the most important ignition sources for fires. The glowing contacts with high temperature are commonly hidden in electric wires. The glowing contact involves complex coupling between the copper oxidation, heat transfer, and electric field. The relationships between the key parameters are investigated experimentally by measuring the growth rate of the oxide bridge length as well as the glowing contact resistance and temperature. The results show that the oxide bridge length and the glowing contact resistance increase with time. The maximum contact temperature increases with time up to 1 400-1 600℃. Increasing currents increase the oxide bridge growth rate and growth time. The increasing rate of the resistance first increases and then decreases with the current increase. The results further show that the glowing contact is due to interactions between the oxidation extent, the changes in the copper oxide resistivity with the current, and the increases in the specific heat with temperature.
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