火灾条件下电缆绝缘失效预测模型研究

Study on the insulation failure prediction model of cable in fire

通过物理模型简化方法、导热微分方程数值求解、模型输入参数确定等研究,建立了火灾条件下电缆绝缘失效预测模型,并进行模型验证试验。将电缆内部结构简化为一维三层物理模型,给出简化后电缆物理模型内部结构参数计算方法;通过基本假设构建表征电缆内部温度分布的导热微分方程式,建立以混合层热扩散系数、火场环境温度变化和电缆绝缘失效温度为输入参数的电缆绝缘失效预测模型,并给出了模型计算输入参数的确定方法;采用ZR-YJV电缆在SDR-1型电缆热辐射实验炉中开展实验,获得电缆绝缘失效温度、绝缘失效时间和环境温度变化过程;实验结果表明,预测模型计算绝缘失效时间的相对误差较小。

Based on the research on simplified method of physical model, heat conduction equation solving method and input pa- rameters determination, a cable insulation failure prediction model in fire was established, and the validation test was car- ried out. The internal structure of the cable was simplified to a one-dimensional physical model with three layers, to derive the calculation method of internal structure parameters of cable physical model. Differential equation of heat conduction, which could reflect the internal temperature of cable, was constructed based on basic assumptions, to establish a cable insulation cable failure prediction model with mixed layer heat diffusion coeffi- cient, environment temperature change and insulation cable fail- ure temperature as input parameters. The method to determine model input parameters was also proposed. ZR--YJV and SDR --1 cable thermal radiation furnace were selected in the experi- ments to obtain insulation failure temperature and time, as well as environmental temperature change of the cable. The experi- mental results showed that the constructed model had relative small error in predicting cable insulation failure time.