SUMMARYAn approach to numerical modelling of temperature distributions around buried power cables using finite element analysis is presented in this paper. The finite element algorithms are based on time-dependent heat sources of the environment and temperature-dependent material properties of the cables. The nonlinear steady-state and transient heat transfer algorithms are applied to the problem of controlling thermal environment in an actual hot spot of a 110 kV cable line installed in Belgrade, Republic of Serbia. Moreover, this paper outlines the influence of an underground heating pipeline on ampacities of the cable line, and two retrofitting procedures for optimising the thermal properties of cable environment. Two suggested procedures for thermal optimisation of the actual hot spot are: the use of a new-mixed corrective backfill and the use of quartz sand. Finally, actual test cases using the measured data indicate the possibilities of using the proposed algorithms.

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This paper describes a new concept in construction of cable terminations for medium voltages. Layers with a high permittivity and embedded electrodes (EEs) were used. Three groups of configurations were examined. In the first group, the layer of high permittivity was placed partly over the cable insulation and partly over the cable screen. In the second group, the high permittivity layer (HPL) was placed partly over the cable insulation and partly under the semiconducting material, connecting with cable insulation screen. In the third group the cable screen was partly inserted into the H P L whose other part was placed over the cable insulation. The EEs were made in a shape of rings around the HPL. The rings were made either of copper tape or copper wire. Different positions of the EEs were examined. Numerical models of the cable L