Ampacity Calculation Of Power Cables By The Multi-field Coupling

Calculating the cable ampacity accurately under laying environment is verysignificant to improve the cable utilization rate and to guarantee long-term andstable operation of the cable. The method of determining the cable ampacitymainly include experimental method、analytic method and numerical method.Determining the cable ampacity by experiment is high cost and not a universalidiosyncratic. The ampacity of cables under complicated laying conditions iscalculated by analytic method exits certain deviation with the actual load capacity.But in recent years, numerical method based on the finite element method and thecomputer technology gains more and more attention on the calculation of thecable ampacity, which has overcome the shortcomings of the two previousmethods.In this paper, the models of electromagnetic field and temperature field of thecable under three typical laying conditions are established by ANSYS, which areused to calculate all kinds of cable losses and the cable ampacity and optimize thearrangement of multi-loop power cables. Moreover, this paper verifies thereliability of several formulas in IEC standard through the finite elementsimulation. The model of actual corrugated sheaths cable is established throughANSYS, which is used to calculate the cable loss and the ampacity. Thesimulation results are compared with the calculations by the IEC standard. Theinfluence of metal sheath on the total armour loss factor of three-core cables withsteel tape armour and the factors affecting the sheath’s loss factor of SL type cableare analysed in this paper,which are not pointed out clearly in IEC standard.The results indicate that the finite element method can handle complex boundary conditions，calculate the multi-field coupling problems, achieve thecalculation of nonlinear field. Therefore the computer simulation based on thismethod is an effective means to calculate the ampacity of the cable under specialstructure and complex laying conditions.