<p>The insulation layer of electrical wiring conductors is mostly made of polyvinyl chloride (PVC) and polyethylene (PE) materials. These materials are prone to ignition under overload or external heating conditions, making them a research hotspot for fire accident investigators and researchers in related fields. To address the issue of short circuits and subsequent fires caused by conductor overheating, this study employed an infrared thermal imager to monitor the evolution of wires under overload conditions and analyzed the pyrolytic characteristics of the external insulation material. By observing the behavior of copper conductors under different current intensities (85, 90, 112.5, 130, 135, 157.5, and 180 A), the thermal degradation process of the insulation layer, the temperature variation patterns of the conductors, and the degree of deformation were analyzed. The results indicated: (1) under overload conditions, the insulation layer of the conductor will smoke, bubble, peel, and carbonize. The initial times of smoking, bubbling, peeling, and carbonization follow a quadratic relationship with the current value. (2) In the temperature distribution of the conductor, a common characteristic under different currents is that the temperature is highest in the middle of the conductor and decreases toward the ends. The temperature change of the insulation layer is significantly influenced by the current, with 135A as the critical point, dividing the temperature change into two stages. (3) During pyrolysis, the conductor softens, and the degree of bending deformation increases with the current value. The relationship between the current value and the degree of deformation is expressed as: <InlineEquation ID="IEq1"> <EquationSource Format="TEX">$y = A + B * I + C * I^{2}$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>y</mi> <mo>=</mo> <mi>A</mi> <mo>+</mo> <mi>B</mi> <mrow /> <mo>∗</mo> <mi>I</mi> <mo>+</mo> <mi>C</mi> <mrow /> <mo>∗</mo> <msup> <mi>I</mi> <mn>2</mn> </msup> </mrow> </math></EquationSource> </InlineEquation>. The research conclusions, based on the observed thermal degradation process and temperature variations, provide experimental evidence and technical support for the investigation of electrical fire accidents, particularly in understanding the thermal failure mechanisms under overload conditions.</p>

Thermal failure behavior of single-core PVC-insulated copper wires under overload fault conditions

期刊论文
发表日期：

2025年11月8日

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Weifeng Wang,
Yixiang Liu,
Cuizhen Lu,
Mengyang Dong,
Zhangkun Chen,
Yu Shao,
Jingyi Zhang,
Xiangjun Liu

摘要

The insulation layer of electrical wiring conductors is mostly made of polyvinyl chloride (PVC) and polyethylene (PE) materials. These materials are prone to ignition under overload or external heating conditions, making them a research hotspot for fire accident investigators and researchers in related fields. To address the issue of short circuits and subsequent fires caused by conductor overheating, this study employed an infrared thermal imager to monitor the evolution of wires under overload conditions and analyzed the pyrolytic characteristics of the external insulation material. By observing the behavior of copper conductors under different current intensities (85, 90, 112.5, 130, 135, 157.5, and 180 A), the thermal degradation process of the insulation layer, the temperature variation patterns of the conductors, and the degree of deformation were analyzed. The results indicated: (1) under overload conditions, the insulation layer of the conductor will smoke, bubble, peel, and carbonize. The initial times of smoking, bubbling, peeling, and carbonization follow a quadratic relationship with the current value. (2) In the temperature distribution of the conductor, a common characteristic under different currents is that the temperature is highest in the middle of the conductor and decreases toward the ends. The temperature change of the insulation layer is significantly influenced by the current, with 135A as the critical point, dividing the temperature change into two stages. (3) During pyrolysis, the conductor softens, and the degree of bending deformation increases with the current value. The relationship between the current value and the degree of deformation is expressed as: $y = A + B * I + C * I^{2}$ $y = A + B * I + C * I^{2}$ . The research conclusions, based on the observed thermal degradation process and temperature variations, provide experimental evidence and technical support for the investigation of electrical fire accidents, particularly in understanding the thermal failure mechanisms under overload conditions.