Induced losses are a significant part of the total losses generated in HVAC cables. Presently, IEC 60287-1-1 is used to calculate the ratio of induced loss in a cable's metal sheath to its conductor loss (λ1), assuming uniform current density in both conductors and sheaths. Although this assumption is reasonable for smaller cables, it is questionable for larger cables in close proximity, such as three-core export cables in the Offshore Wind Farm projects. The effects of this non-uniform current density cannot be easily treated via a straightforward, purely analytical approach, since conductor currents are not effectively represented by linear ones in larger cables, while sheath currents are also unevenly distributed. The present study employs two-dimensional finite element models to evaluate how accurate the Standard method for calculating the λ1 factor is in cables with a nonmagnetic armor. Their validity is further enhanced by means of filament method. The IEC 60287 appears to overestimate the temperature, particularly for larger conductor sizes, by up to 7 °C (8%). Finally, suitable reductive factors are suggested, which could improve the accuracy of the IEC method.

中文翻译：

---

三叶形电缆布置中邻近效应对护套损耗的影响

感应损耗是 HVAC 电缆产生的总损耗的重要组成部分。目前，IEC 60287-1-1 用于计算电缆金属护套中的感应损耗与其导体损耗 (λ1) 的比率，假设导体和护套中的电流密度均匀。尽管这种假设对于较小的电缆是合理的，但对于距离较近的较大的电缆，例如海上风电场项目中的三芯出口电缆，这是有问题的。这种不均匀电流密度的影响无法通过简单的纯分析方法轻松处理，因为在较大的电缆中导体电流不能有效地由线性电流表示，而护套电流也分布不均匀。本研究采用二维有限元模型来评估用于计算 λ1 因子的标准方法在具有非磁性铠装的电缆中的准确度。它们的有效性通过灯丝方法进一步增强。IEC 60287 似乎高估了温度，尤其是对于较大的导体尺寸，高达 7 °C (8%)。最后，提出了合适的还原因子，以提高IEC方法的准确性。