含防爆盒的三芯电缆中间接头散热性能及载流量研究

为了避免电缆遭受外力破坏，防止中间接头故障后蔓延至临近电缆，电缆中间接头需加装防爆盒，如此势必延长中间接头热传导的路径，影响其散热性能。为了进一步探究配电网三芯电缆中间接头加装防爆盒后的温度及载流特性，本文以20kV三芯电缆中间接头为例，建立考虑接触电阻的三芯电缆中间接头磁-热耦合模型，计算了289A电流下含防爆盒的中间接头温升，对比运行数据验证了仿真计算的准确性，然后进一步分析了防爆盒对中间接头载流量的影响规律。结果表明：防爆盒内的空腔会大大降低中间接头的散热性能，相比于电缆本体时，载流量约下降37.1%，而灌注环氧树脂ab胶后，可以大幅度增强中间接头的散热，相对于未灌胶时载流量提升近41.1%。研究结果可为防爆盒的设计及中间接头运维的制定提供参考，有益于电缆的安全稳定运行。

Research on Heat Dispersion and Ampacity of Three-Core Cable Joints with Explosion-Proof Box

To avoid cable faults caused by outside destroy and prevent the failure of cable joints from spreading to other nearby cables after a fire, the explosion-proof box must be added to the newly installed cable joints according to the latest regulation. Given that the sealing of explosion-proof box will increase the heat transfer path, it will inevitably affect the heat dissipation performance of cable joints. To further study the temperature rise and ampacity characteristics of the three-core cable intermediate joint with explosion-proof box in distribution network, this paper takes the joint of 20kV three-core cable as an example, then develops the magnetic-thermal coupling model of the three-core cable joint on the basis of contact resistance. The temperature rise of the joint with explosion-proof box under 289A current is calculated, and the accuracy of simulation calculation is verified by comparing the operation data. Finally, the influence of the explosion-proof box on the current carrying capacity of the joint is analyzed. The cavity in the explosion-proof box greatly reduces the heat dissipation performance of the joint. Compared with cable body, the ampacity is reduced by about 37.1%, while the heat dissipation of the joint can be greatly enhanced by pouring the epoxy resin ab glue, The current carrying capacity is increased by nearly 41.1% compared with that without the epoxy resin ab glue. It can provide a reference for the development of operation strategy, which is helpful to the safe and stable operation of three-core cables.