Electrical Engineering

, Volume 101, Issue 4, pp 1295–1309 | Cite as

Eliminating the effect of hot spots on underground power cables using cool pavements

  • Dardan KlimentaEmail author
  • Dragan Tasić
  • Bojan Perović
  • Jelena Klimenta
  • Miloš Milovanović
  • Ljiljana Anđelković
Original Paper


It is well known that hot spots limit the ampacities of underground power cables. There are many commonly applied methods to control the thermal environment in hot spots of underground power cables. However, applications of cool pavements for this specific purpose would be a novelty in the field of power cable engineering. This paper considers the use of different cool pavements in combination with thermally stable bedding and/or pure quartz sand for mitigating or eliminating the thermal effect of an actual hot spot on the ampacities of a 110 kV cable line and a group of four 35 kV three-core cables installed in Belgrade, the Republic of Serbia. In the hot spot, the 110 kV cable line is installed in parallel with the group of 35 kV cables and crosses a district heating pipeline. All distances between these underground installations are lower than the recommended ones, and the 110 kV and 35 kV cables are laid at depths greater than required. The mutual thermal effects between the underground installations in the hot spot are simulated using FEM-based models for different environmental conditions. An experimental background is also provided. In comparison with the corresponding base cases, it has been found that the ampacities of the 110 kV cable line and group of 35 kV cables can be increased up to 25.1% and 60.9% in summer, and up to 62.8% and 170% in winter, respectively.


Ampacity Cool pavement Finite element method (FEM) Hot spot Power cable Thermal effect 

List of symbols

Variables and coefficients


Conductor diameter (m)


Heat transfer coefficient due to convection [W/(m2 K)]


Load current (A)


Cable ampacity (A)


Thermal conductivity [W/(m K)]


Length of the normal vector \( \vec{n} \) (m)


Solar irradiance incident on the earth surface (W/m2)


Volume power of heat sources (W/m3)


Specified heat flux on the upper surface of the heating-pipe duct (W/m2)


Effective conductor resistance to the flow of alternating current, i.e. effective a.c. resistance (Ω/m)

\( S_{\text{c}}^{\prime} \)

Geometric cross-sectional area of conductor (m2)


Unknown temperature or unknown surface temperature (K)


Temperature of the air contacting the earth surface (K or °C)


Temperature of the most thermally loaded conductor (°C)


Continuously permissible temperature of cables (°C)


Wind velocity (m/s)

x, y

Cartesian spatial coordinates (m)


Solar absorptivity (dimensionless)


Thermal emissivity (dimensionless)


Stefan–Boltzmann constant [W/(m2 K4)]


2D and 3D

Two-dimensional and three-dimensional

EUR and €

National currency of the European Union member states


Finite element method


High-density polyethylene


Single-core power cable, N—standardised/norm type, A—aluminium conductor, 2X—cross-linked polyethylene insulation, S—copper screen, FL—longitudinally and crosswise water-tight, and 2Y—polyethylene outer sheath


Three-core power cable, N—standardised/norm type, A—aluminium conductor, EK—metal sheath of lead with corrosion protection on each sheath, E—thermoplastic sheath and inner protective covering, lapped bedding with additional layer of plastic tape, B—armour of steel tape, and A—outer protection of fibreous material (jute) in compound




Pure quartz sand


International System of Units


Thermally stable bedding


Cross-linked polyethylene



This paper was based on research conducted within the project TR33046 funded by the Ministry of Education, Science, and Technological Development of the Republic of Serbia. Also, the authors would like to thank Aleksandra D. Kuč for her technical assistance.


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  • Dardan Klimenta
    • 1
    Email author
  • Dragan Tasić
    • 2
  • Bojan Perović
    • 1
  • Jelena Klimenta
    • 3
  • Miloš Milovanović
    • 1
  • Ljiljana Anđelković
    • 1
  1. 1.University of Priština in Kosovska MitrovicaKosovska MitrovicaSerbia
  2. 2.University of NišNišSerbia
  3. 3.ProElectric SDKraljevoSerbia

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