电缆敷设数量和间距对电缆燃烧特性的影响分析

Study on the influence of laying quantity and laying spacing on the burning characteristics of cables

通过氧指数测试仪、垂直燃烧测试仪和辐射锥测试分析了耐火电缆和普通电缆的护套层的燃烧性能,并结合电缆燃烧试验分析电缆数量和敷设间距对电缆燃烧性能的影响。结果表明:普通电缆护套层的极限氧指数(LOI)为25.5%并通过垂直燃烧V-0级测试,燃烧过程中存在明显收缩卷曲现象,无法有效保护内部线芯材料;而耐火电缆护套层的LOI达到34.5%,燃烧过程中能够形成致密的膨胀炭层,可有效保护内部线芯结构。电缆燃烧试验表明:电缆的火灾危险性随电缆敷设数量的增加而逐渐增大,随电缆敷设间距增加而逐渐减小。与紧密排列时相比,电缆敷设间距为电缆直径的2倍时耐火电缆和普通电缆的平均质量损失分别降低了87.1%和97.6%,平均炭化长度分别降低了92.6%和92.9%,电缆的火灾危险性最低。此外,与耐火电缆相比,普通电缆的火灾危险性受电缆敷设数量和间距的影响更大。

The combustion properties of the sheath layer materials of fire-resistant cables and common cables were analyzed via oxygen index(LOI)tester,vertical combustion tester and radiation cone.Combined with cable tunnel model test,the influence of the quantity of cables and laying spacing on the combustion properties of two kinds of cables were investigated.The results show that the LOI value of the sheath layer materials of common cables is 25.5%,and it passes the vertical combustion V-0 rating,and there is obvious shrinkage curl phenomenon during the combustion process,it can not effectively protect the internal core material.The LOI of fire-resistant cable is 34.5%,and it can form a dense expanded carbon layer to protect the internal core structure effectively during the burning process.Cable burning test shows that the fire hazard of cables increases gradually with the increase of cable laying quantity and decreases gradually with the increase of cable laying spacing,among which the fire hazard of cables is the lowest when the cable laying spacing is 2 times of the cable diameter.Compared to the tight arrangement,the average mass loss of fire-resistant cables and common cables are reduced by 87.1%and 97.6%respectively,and the average char length was reduced by 92.6%and 92.9%,respectively.In addition,compared with fire-resistant cables,the fire hazard of common cables is more influenced by the quantity and spacing of cable laying.