外热源干扰下电缆载流量计算及通风增容分析

Calculation of Cable Capacity and Ventilation Capacity-increase Analysis Under External Heat Source Interference

为了更加准确地计算外热源干扰下电缆沟电缆载流量,实现通风增容目的,建立了外热源干扰下热-流耦合三维模型。采用ANSYS仿真获得电缆温度分布,进而利用双点弦截法精确计算电缆载流量,并在不考虑外热源情况下,通过IEC标准验证了该模型的准确性。通过实例仿真分析得出,外热源功率(表面温度)每升高1K,载流量下降0.9~1.8A;载流量随距离增大而变大,直至2.5m时影响不大;电缆载流量随通风速度变大而变大,但增长梯度变小;通风温度每升高1K,载流量下降3.5A,呈线性相关趋势。这为外热源干扰下电缆沟敷设提供了最佳施工方案,且为电缆沟电缆增容提供了指导。

Three-dimensional model of external heat source heat-flow couple was established for the accurate calculation of cable trench ampacity and the capacity-increase of ventilation.ANSYS was used to simulate cable temperature distribution.And then the double point string cutting method was adopted to calculate the cable ampacity.The accuracy of this model was verified in comply with IEC standard regardless of the external heat source.The example simulation analysis indicates that when external heat source power（surface temperature）increases 1 K,the ampacity reduces 0.9-1.8 A;The ampacity increase with the distance going larger until 2.5 m.The cable ampacity increases with the ventilation increasing,but the increase gradient is smaller;The ventilation temperature increase 1 K,the ampacity decreases 3.5 A,they are in a linear correlation trend.Therefore,it provides optimal plan for establishing cable duct facilities as well as provides guidance for cable capacity-increase.