The construction of the transmission lines, in the middle of the cities, are always a big challenge for the designers, industry, government and electric utilities. Components of the project, in the electrical, mechanical and civil works are designed for a high reliability, however, the underground cable design according to international standards have some discrepancies, due to this challenge, a new proposal for the new design and engineering failure analysis. Our findings included a case study of a real underground transmission lines with important contribution with models and mathematical calculation for ampacity calculation as function of depth, temperature, screen connection, materials and thermal analysis for transitory and normal operation of the underground cable in high voltage. This novel proposal generates a recommendation for an update of the international standards IEEE, IEC in the next version.

在城市中部，传输线的建设对设计师，工业，政府和电力公司始终是一个巨大的挑战。在电气，机械和土木工程中，该项目的组件设计具有很高的可靠性，但是，由于这一挑战，根据国际标准进行的地下电缆设计存在一些差异，因此需要进行新设计和工程故障分析的新建议。我们的发现包括对真实地下地下输电线路的案例研究，该模型对深度和温度，屏蔽层连接，材料和热分析的功能进行了计算，载流量的模型和数学计算对于高压地下电缆的瞬态和正常运行具有重要作用。