Electromagnetic and Thermal Analysis of Power Losses in Metal Sheaths of Unarmored and Armored Power Cables

In this study, active power losses occurring in the metallic sheaths of single-core unarmored and armored power cables utilized in high-voltage power transmission and distribution systems are rigorously investigated via analytical and electromagnetic approaches. Under alternating current (AC) operating conditions, the underlying physical mechanisms generating induced eddy and circulating currents on the sheath surface are mathematically derived based on Maxwell's equations and Faraday's Law of Induction. Skin and proximity effects, which introduce asymmetry into the current density distribution across the conductor cross-section, are explicitly modeled in compliance with the international standard IEC 60287. To quantitatively evaluate the impact of these theoretical formulations on practical engineering systems, a comprehensive full-step analytical scenario is established for a single-core 1×240 mm² XLPE-insulated steel-sheathed cable line under a solid-bonded configuration at both ends. The restrictive effects of the induced sheath losses on the cable's thermal budget and core ampacity are explicitly quantified and discussed