防火泥在阻燃A类电力电缆中的应用验证
Application Verification of Fireproof Mud in Flame-Retardant Class A Power Cables
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摘要: 针对额定电压0.6/1 kV阻燃A类电力电缆燃烧性能不稳定的问题,以WDZA-YJY 3×50 mm2+1×25 mm2、2×95 mm2、4×120 mm2+1×70 mm2、3×185 mm2 等4种规格电缆为研究对象,分析常规结构(非紧压绞合圆形铜导体 + 交联聚乙烯绝缘 + 聚丙烯填充绳 + 绕包高阻燃带 + 挤管式护套)的不足,通过3次优化提升其燃烧性能:第1次将导体改为紧压型线铜导体、填充绳替换为阻燃材料;第2次增加高阻燃带绕包层数至4层、护套挤出方式改为半挤压式;第3次引入防火泥挤包隔氧层替代传统填充绳与部分包带结构。试验结果表明,常规结构电缆燃烧试验合格率仅20%,炭化高度普遍超过2.1 m,优化后电缆炭化高度均不大于0.9 m,一次性通过阻燃A类燃烧试验,合格率达100%,且性能成本比显示第3次改进的结构性价比较高。研究显示,防火泥隔氧层与高阻燃带的复合结构通过膨胀隔氧、吸热降温及物理阻火的协同作用,可显著抑制火焰传播,为阻燃A类电缆的设计提供了技术范本,但需要注意外径增大、载流量下降等衍生问题以平衡综合性能。Abstract: Four cable specifications (WDZA-YJY 3×50 mm2+1×25 mm2, 2×95 mm2, 4×120 mm2+1×70 mm2, and 3×185 mm2) were focused on to address the instability in combustion performance of 0.6/1 kV flame-retardant Class A power cables. Shortcomings of conventional structure (non-compacted stranded round copper conductor + cross-linked polyethylene insulation + polypropylene filling rope + wrapped high flame-retardant tape + tube-type extruded sheath) were analyzed, and three rounds of optimization were conducted to enhance their combustion performance. First optimization: replacing the conductor with a compacted profile copper conductor and the filling rope with a flame-retardant material; second optimization: increasing the number of high flame-retardant tape wrapping layers to 4 and changing the sheath extrusion method to semi-extrusion; third optimization: introducing a fireproof mud extruded oxygen barrier layer to replace traditional filling rope and partial tape structure. Test results showed that pass rate of conventional structure in combustion tests was only 20%, with carbonization heights generally exceeding 2.1 m. After optimization, all cables exhibited carbonization heights below 0.9 m, successfully passing flame-retardant Class A combustion test on the first attempt with a 100% pass rate. Performance-cost ratio analysis indicated that the third improved structure had extremely high cost-effectiveness. The study demonstrated that composite structure of the fireproof mud oxygen barrier layer and high flame-retardant tape significantly suppressed flame propagation through synergistic effects of expansion-induced oxygen isolation, heat absorption cooling, and physical fire resistance, providing a technical template for the design of flame-retardant Class A cables. However, attention must be paid to derivative issues such as increased outer diameter and decreased current-carrying capacity to balance comprehensive performance.
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