Cable tray cable is easy to catch fire. Why? Some of the materials used in the cable are flammable. When the ignition and combustion of local cable reaches high temperature, it will melt. When the ignition temperature exceeds the adjacent cable, it will cause the cable to burn for a long time. This problem is very serious, not only damaging the bridge, but also endangering the safety of people. In order to solve the fire problem, we need to know what causes the bridge cable to catch fire. Therefore, the following are some reasons for the fire of Jinan cable bridge.

　　1. 电缆电流设计不当

　　1. Improper design of cable current

　　电缆负荷选择不当，部分电缆长期满载或经常超负荷运行，导致电缆沟、隧道温度升高、电缆老化、受潮、过热等短路自燃。

　　Improper selection of cable load, long-term full load or frequent overload operation of some cables, resulting in temperature rise of cable trench and tunnel, cable aging, damp, overheating and other short-circuit spontaneous combustion.

　　2. 电缆安装和施工不当

　　2. Improper cable installation and construction

　　在电缆桥架施工中，有的机组没有采取防火措施，电缆敷设混用，经常会产生有毒烟雾，将中低压电缆和高压电缆敷设在一起;在铺设电缆时，部分施工人员没有严格遵守操作规程和技术要求，经常因刮擦、碰撞、压力、扭转等原因造成电缆外层损坏。水易受湿气影响，运行过程中保温层损坏，引起电弧和火灾。

　　In the construction of cable bridge, some units have not taken fire prevention measures, and the cable laying is mixed, which often produces toxic smoke, laying the medium and low voltage cables together with the high voltage cables; when laying the cables, some construction personnel fail to strictly abide by the operating procedures and technical requirements, and often damage the outer layer of the cables due to scratch, collision, pressure, torsion and other reasons. Water is easy to be affected by moisture, and the insulation layer is damaged during operation, causing arc and fire.

　　3.电线电缆故障

　　3. Wire and cable failure

　　电线电缆的故障有以下几种:(1)电缆桥架电缆生产粗糙，保温层受潮，导致电缆头和端子盒在运行中失效和自燃、爆炸;

　　The faults of wires and cables are as follows: (1) the production of cable bridge and cable is rough, and the insulation layer is damp, which leads to the failure, spontaneous combustion and explosion of cable head and terminal box in operation;

　　(2)有些电缆技师操作不严格，不注意卫生，杂质、污物清洗不干净，造成接口接触不良;

　　(2) Some cable technicians operate not strictly, do not pay attention to sanitation, impurities, dirt cleaning is not clean, resulting in poor interface contact;

　　接头工艺不精细，生产质量不高，防火措施少，在发生故障时受高压、大电流冲击造成接头起火;

　　The joint process is not fine, the production quality is not high, and the fire prevention measures are few. The joint fires due to the impact of high voltage and large current in case of failure;

　　(4)接地电缆不良，地线焊接不牢固，接触不良，电阻值过大，导致电缆接地故障电流比正常短路电流小，使电流保护器不能及时切断故障，并出现电弧、火花。

　　(4) The grounding cable is poor, the ground wire is not welded firmly, the contact is poor, and the resistance value is too large, which causes the cable grounding fault current to be smaller than the normal short-circuit current, so that the current protector cannot cut off the fault in time, and there are arcs and sparks.

　　让我们总结一下原因引起的济南电缆桥架主要是电线电缆过载,短路,过多的接触电阻和外部热源作用,在短路,局部过热等故障状态和外部加热作用,绝缘材料电阻下降,失去绝缘能力甚燃烧,然后引起火灾。因此，在施工过程中必须考虑火灾因素。做好防火措施和应急准备是非常重要的。

　　Let's summarize the main causes of Jinan cable bridge are wire and cable overload, short circuit, excessive contact resistance and external heat source effect. In short circuit, local overheating and other fault states and external heating effect, the resistance of insulation material decreases, loss of insulation capacity or even burning, and then fire. Therefore, fire factors must be considered in the construction process. It is very important to do well in fire prevention measures and emergency preparedness.