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The continuous increase in the demand for electricity makes it necessary to modernize or build new transmission lines. This, in turn, results in research that is still being carried out on the optimal use of power cables. In the paper, an improved analytical method for the determination of the current rating of power cables was proposed. The method...
Contexts in source publication
Context 1
... dependence of the current rating of the cable on the thermal resistivity of the soil. Figure 7 shows the dependence of the rated current of the cable on the depth of burial. The calculations were made for cables buried in the soil of thermal resistivity ρsoil = 1.25 Km/W. ...
Context 2
... dependence of the current rating of the cable on the thermal resistivity of the soil. Figure 7 shows the dependence of the rated current of the cable on the depth of burial. The calculations were made for cables buried in the soil of thermal resistivity ρsoil = 1.25 Km/W. ...
Citations
... Various studies have highlighted the advantages of computer-based calculators and finite element methods for thermal calculations regarding cables. The reliability and accuracy of the results acquired using these methods have been demonstrated [10,11]. ...
Underground cable installation in historical areas, natural protected areas, narrow streets, or residential areas with high traffic flows is very difficult due to both legal permits and the conditions of the work sites. The trefoil layout requires a smaller channel than the flat layout. However, the trefoil layout carries some risks, such as damage to the cables together in the event of short circuit faults and reduced ampacity in single-side-bonded systems. This study’s scope examines the current carrying capacities and thermal effects of directly buried underground cables in trefoil and vertical layouts using CYMCAP power cable analysis software. A field investigation was also carried out to verify the analysis results. The performance of the recommended method was evaluated by considering current and temperature measurements from the fieldwork and analysis. According to the studied cable design, the current carrying capacities of the cables in flat and vertical layouts are similar and higher than in the trefoil layout. However, it should be taken into consideration that these results will vary depending on a cable system’s design parameters. As a result, this article emphasizes that a vertical layout can be considered as a layout option in certain areas.
... In [11], an estimation of the temperature rise of a highpower contactless transformer used in railway power supply systems was made by means of the method of thermal resistances. In [12], the method of thermal resistances, together with analytical expressions for current density, was used to determine the ampacity of a three-phase cable with round conductors. ...
... Among them, finite elements are the most often encountered (e.g., [4,5,8,10]), but sometimes finite differences are used (e.g., [9]). However, numerical methods often require considerable computational effort; therefore, circuit-based methods are used, like the method of thermal resistances (e.g., [7,11,12]), or other thermoelectric equivalent methods, like in [16]. To enhance the accuracy and lower the computational effort, finite elements and circuit-based methods are sometimes used together (e.g., [17,18]). ...
... Due to the complex form of g(ξ, θ), it is impossible to calculate the integrals in (12) analytically for g given by Equations (5) and (1). Nevertheless, Formula (12) may be the basis for obtaining simplified solutions, e.g., by expanding the Bessel functions appearing in (1) into appropriate series [30]. ...
This paper presents a semi-analytical method for determining the distribution of the thermal field in a system of two parallel round conductors, taking into account the skin and proximity effects. The method of a suitably constructed Green’s function was applied to find an analytical expression for the eigenfunctions describing the temperature distributions. In turn, the relevant integrals, which cannot be determined analytically, were calculated numerically. The foundation of the method is the knowledge of the current density distribution in the conductors. As a result, the steady-state distribution of the temperature field in the conductors for various parameter values can be determined. The obtained numerical results were positively verified using the finite element method. Using the developed method, the share of skin and proximity effects in the temperature rise and steady-state current rating was evaluated. Closed analytical formulas were obtained for the AC case with the skin effect taken into account. When the skin depth is smaller than the wire radius, the skin effect has quite a large impact on the conductor temperature. The impact of the proximity effect is much smaller but clearly noticeable when the distance between the wires is smaller than five times the wire radius. In addition, the influence of the value of the heat transfer coefficient on the thermal field of the conductors was also examined.
