Research On Fire Prevention Of Underground Cable Channel In Substation

With the rapid development of the society,the construction requirements for urban infrastructure are becoming higher and higher.The construction of municipal pipelines should be transformed according to urban planning,which will make the underground cable pipes become the main mode of power supply for the substation.However,underground cables and pipelines bring convenience to human beings,but at the same time,they also cause fire risks.Once the underground cable fires,it will not only produce a large number of toxic fumes,but more seriously affect the normal operation of the substation,causing serious economic losses.Therefore,this paper studies the fire protection of underground cables in substations,and then puts forward reasonable fire-retardant measures and fire protection suggestion when cable fires happen.This paper makes a theoretical study on the causes and characteristics,hazard analysis and flame retardant mechanism of cable fire.Combined with the calculation principle of fluid dynamics model and combustion model,the risk and influence factors of underground cable fire and the fire protection effect of the fire wall to underground cable trench are simulated with PyroSim.The results and conclusions are as follows:(1)Through the summary of the characteristics of underground cable fire,fire cause and flame retardant mechanism,cable classification and combustion characteristics,the development law of underground cable fire is obtained,which provides a certain theoretical basis for the simulation of underground cable fire,the analysis of influence factors and the research of fire resistance of fire wall.By simulating the fire scene of underground cable and analyzing the danger of the fire,the spread process of the smoke of underground cable fire,the characteristics of temperature field,the content of flue gas and the change process of CO volume fraction are obtained.(2)By using PyroSim simulation software to analyze the effect of fire resistance of the cable trench wall.The results are as follows:In view of the danger of the underground cable fire and the disadvantages of the traditional resistance wall,a new type of fire wall can be set up effectively to slow the spread of the flame and prevent the cable from being delayed.For the cable fire simulation in the effective time,under the action of the new type of fire wall,there is no smoke in the periphery of the fire source area,and the effect of smoke isolation is achieved.The temperature reaches 20 degrees centigrade,the effect of heat insulation is reached,the heat release rate reaches 13300 kw,the decrease of 700kw;the burning rate of0.97kg/s,The new type of fire wall reduces the heat release rate and the burning amount of the cable,and the new resistance wall reduces the harm of the underground cable fire and inhibits the transmission of the 0.64kg/s.The new resistance wall reduces the damage of the underground cable fire and inhibits the transmission of the CO.By improving the structure and material of the traditional fire resisting wall aspect,the fire resistance and good effect of the new firewall.(3)Through the flame retardant simulation study of cable sheath material and cable tunnel section structure,the results show that the flame retardant PVC sheath material and polypropylene sheath material have a good smoke suppression effect.The circular section cable tunnel played the role in heat insulation,the peak value of heat release rate and heat release rate were the lowest,and the burning rate reached 1.16kg/s.The circular section structure cable tunnel effectively reduced the heat release rate and the combustion volume of the cable.(4)The simulation of underground cable fire from three aspects of laying depth,cable spacing and cable arrangement is carried out.The results show that the laying depth of underground cables has a great influence on the cable fire in a certain range.The greater the laying depth of the cable,the less energy of the heat exchange with the ground,the shadow of the cable fire.The smaller the 1m,the better the laying depth is,and the reasonable laying distance is conducive to the heat dissipation of the cable itself.When the spacing of the cable is between 0.1~0.2m,the cable will affect each other and the cable temperature will increase.It is suggested that the selection of 0.15 m cable laying spacing is appropriate;the selection ofreasonable cable arrangement will have a certain influence on the cable fire.The parallel arrangement of cable is lower and the cable should be selected first.The form of parallel arrangement.