Application of finite element method to compare the installation requirements in a buried cable according to IEC60287 standards

In this paper, the thermal analysis of an installed underground XLPE- insulated single core power cable with flat formation, is presented. Quickfield© is the software used to simulate and evaluate the current rating in the buried cable, using specific boundary conditions. Quickfield© is a Finite Element Method CAD modeling software that supports a variety of electromagnetic, thermal and stress analysis problems that have either two-dimensional
x-y
symmetry or axial symmetry. IEC 60287 standards are applicable to the conditions of the steady-state operation of cables, at all alternating voltages and direct voltages up to 5 kV, buried directly into the ground without partial drying-out of the soil. The current rating calculations (IEC60287.1-1) and thermal rating calculations (IEC60287.2-1) were used for calculation purposes. A system of three single core power cables arranged in flat formation is buried in multi-layered soil. The cable line burial depth used is 1000mm, the thermal resistivity of the soil is 1.2K.m/W and the temperature of the soil used is 30˚C. These boundary conditions were used to simulate and evaluate the current rating of the cable. The purpose of this study is to compare the current rating of an underground XLPE-insulated single core power cable calculated according to IEC60287 from a manufacturer to the simulation results. The results were obtained using the finite element software Quickfield© to show the impact on the outcome on real life installation conditions. The results obtained with the software, when the assumption is made that the soil is radial and also isotherm, correlates with the calculated results obtained using the analytical method based on the analogy between an electrical circuit and a heat flow circuit. The analogy used when calculating the current rating was that the heat flow in the circuit corresponds to the current rating in a buried cable. The simulation results were analysed and compared with the manufacturer's data and calculated according to IEC60287 standards.