Calculation of the ampacity of high voltage cables by accounting for radiation and solar heating effects using FEM

摘要

The paper presents a finite-element model for the evaluation of the ampacity of an underground 110-kVnthree-phase system of cables in normal operation and in case of emergency. The proposed model takes theneffects of convection, radiation, and solar heating at the trench surface into account, which enhances the previousnapproaches. The calculations performed have shown that these phenomena affect the heating of cablesnand that the IEC approach that treats the trench surface as an isothermal plane at ambient temperature, widelynused in practice, might underestimate the ampacity of cables in certain cases. The model considers in detailnthe shape and construction of the cable trench, and the thermal properties of backfilling materials and concretenand asphalt covers including the effects of the drying out of soil. The effects of various approximationsnhave been also investigated. The model has been applied to a real life example, and the calculation resultsnhave been compared to some experimental data. Copyright © 2011 John Wiley & Sons, Ltd.