热辐射作用下电缆绝缘失效时间预测  

Study on predicting cable insulation failure in case of heat radiation

作　　者：舒中俊[1] 王霁[1] 孙青辉[1] 张克俭[1] 

机构地区：[1]中国人民武装警察部队学院,河北廊坊065000

出　　处：《安全与环境学报》2011年第5期188-192,共5页Journal of Safety and Environment

基　　金：公安部应用创新计划项目(2010YYWJXY121)

摘　　要：电缆绝缘材料在火灾条件下的失效时间对于电缆工程的设计和施工是一个非常重要的参数,这些数据多以试验的方式获得。以试验结果为基础,在假设的前提下,运用传热学理论建立了电缆在热辐射作用下其内部的温度分布模型,并应用MATLAB软件中的pdepe函数求得了模型的数值解,即电缆内部各点温度随时间的变化关系,据此获得电缆绝缘失效时间。以ZR-VV电缆为研究对象,应用该模型计算得出了热通量分别为3 kW/m^2、5 kW/m^2、7 kW/m^2、24 kW/m^2、40 kW/m^2和56 kW/m^2时,电缆内部的温度分布及失效时间。计算值与试验结果吻合较好,说明使用所建立的模型可以近似预测电缆在不同热辐射条件下的绝缘失效时间。The present paper is inclined to introduce our study results on how to predict the cable insulation failure in case of heat radiation because we believe that it is of fatal importance for the construction workers to know how to prevent such disastrous accidents. It is just for such reasons that we have been attaching particular attention to the study of the vulnerability of electrical cables when exposed to fire, trying to gain the precise data leading to the failure. For this study goal, we have conducted a series of experiments based on reviewing technical literature concerning the problem. However, the critical in- sulation failure moment or instant, at which the failure is supposed to take place can only be predicted by establishing a temperature model of cable in different fire conditions. Therefore, this paper has pro- posed a model of internal temperature distribution of the cable when it is exposed to external radiation sources based on the results of our ca- ble insulation failure experiments, the reasonable hypotheses and heat transfer theories concerned. And in turn we have established the dif- ferential equation by using the MATLAB function of pdepo, and found the time-temperature relation at each point of the cable. The internal temperature of ZR - VV cable has been worked out by means of the model in six heat flux points, which were 3 kW/m2, 5 kW/m2, 7 kW/m2, 24 kW/m2, 40 kW/m2 and 56 kW/m2, respectively. The six heat flux points can be used to simulate the fire scenario of cable placed inside the wall or exposed directly to the fire. Numerical sim- ulation results from the model tests prove to be in corrspondence with the experimental ones. Thus, it can be concluded that once setting the accurate and reasonable parameters of all the other kinds of ca- ble, the insulation failure moment or instant of a cable can be pre- dicted by using the model when exposed to a heat flux. Hence, the numerical results prove to be useful for designing a cable project and fire hazard assessment as a reference.

关 键 词：安全工程 电缆 热辐射 温度场 绝缘失效 MATLAB 

分 类 号：X934[环境科学与工程—安全科学]