Modelling and sensitivity analysis of the thermal behaviour of cables for different current conditions

Asymmetry, unbalance and nonlinearity of loads affect the current distribution in both phase and neutral conductor cores in three phase power supply systems. Especially in cases of nonlinear single phase loads the neutral conductor can be loaded with an excessive current. Consequently, cable temperature, which is directly related to the power dissipation, is highly affected. Applying a maximum insulation temperature as boundary condition, the power conducting capacity of LV-cables will substantially be affected by asymmetry, unbalance and especially nonlinearity of loads. Physical cable parameters with respect to both thermal resistance and cable geometry were analyzed in order to determinate the most relevant influencing parameters. The temperature distribution in the cable section is thermally calculated and is subsequently simulated, using 2D finite element modelling. Finally, measurements of the cable temperature are performed verifying the simulation results.