Comparison of finite element analysis to IEC-60287 for predicting underground cable ampacity

The ampacity of underground power cable lines is limited by the maximal allowable temperature of the conductor. Normally the IEC 60287 standard is used for steady state ampacity calculation. The standard employs the concept of thermal equivalent circuit. An alternative to the standard is the finite element (FEA) simulation of electromagnetic and thermal field around cables. This paper presents a systematic comparison of IEC calculation vs. FEA simulation for various cable line layout. The simulation includes coupled AC magnetic formulation with attached circuit and heat transfer formulation. The comparison shows that IEC and FEA gives almost same results with single-core cables laid in trefoil or flat formations. In case of cable duct bank with a number of lines, FEA shows a stronger electromagnetic and thermal interference than predicted by the IEC 60287 standard.