Abstract
In the last decade, design engineers have been increasingly required to calculate the ampacities of cable lines using the finite element method (FEM) according to IEC TR 62095, especially for cases that cannot be solved analytically based on IEC 60287. In this regard, CIGRE Study Committee B1 noted in 2020 that there are many gaps in the technical report IEC TR 62095 and then published in 2025 a technical brochure. However, a certain number of those gaps still remained unaddressed. This paper proposes concrete solutions for addressing several gaps related to underground single-core power cables in trefoil formations. 110 kV single-core cables with cross-linked polyethylene insulation are considered, and FEM-based modeling is used for their steady-state thermal analysis. FEM-based models utilized here assume that the cables are installed directly in the dried-out soil, without cable bedding, under the most unfavorable ambient conditions. Appropriate analytical IEC-based models are used to verify the correctness of the proposed solutions. The ampacity obtained using the FEM differs from the corresponding IEC 60287-based value by only -0.263%, and the maximum conductor temperature deviations from the continuously permissible temperature are lower than 0.01 °C. The differences guarantee the reliability of FEM-based calculations.