利用红外辐射加热炉及绝缘电阻测量系统,研究了ZC-YJV和YJV两种电缆,在穿涂有不同厚度钢结构防火涂料金属管保护方式下,模拟IS0 834标准火灾条件时,绝缘电阻的失效时间及温度.结果表明,两种型号的电缆在试验的涂层厚度范围内,绝缘失效时间与涂层厚度呈正比例关系,幂指数为1.3,当金属管外防火涂料的涂层厚度小于1 mm或大于3 mm时,保护效果均不明显,防火涂料的涂层厚度范围应以1 ～2.5 mm为宜.不同型号的电缆其绝缘失效温度有所不同,绝缘失效温度越高耐火性能越好,在火灾中保持线路完整性的能力越强.%The insulation failure time and temperature of ZC-YJV and YJV electric cables that were inserted in the fire retardant coating coated conduit were studied by means of the infrared radiation heating furnace and insulation resistance measurement system. The temperature-time curve inside the furnace was similar to the ISO 834 standard one. The results show that, for the two kinds of cable, the insulation failure time increases along with the thickness of the coating,and the power of exponent is 1. 3. The suitable range of the coating thickness is from 1 mm to 2. S mm, for, with the steel structural coating thinner than 1 mm or thicker than 3 mm, the protective effect is not remarkable for the relative small expansion multiple. Different types of cable have different insulation failure temperatures. And the higher the temperature, the better the fire resistance of insulation.
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