Slavoljub R. Aleksić

Hybrid Boundary Element Method for Multi-Layer Electrostatic and Magnetostatic Problems

Abstract A hybrid numerical method is proposed involving a successful combination of the equivalent electrodes and boundary element method. Electric field and electric potential distribution are determined by using both equivalent electrodes and equivalent charges. Greens function for potential of the charge per unit length, placed in free space, on the boundary of two dielectrics, is used. Magnetic-field distribution is determined by applying equivalent currents through magnetic vector potential and substitution of Amperes microscopic currents with total currents. The accuracy of the developed method is highlighted with some simple numerical examples.

Hybrid Boundary Element Method and Quasi-TEM Analysis of Two-Dimensional Transmission Lines—Generalization

Abstract The hybrid boundary element method, based on the equivalent electrodes method and the boundary element method, is presented in this article. This method is applied on several examples for calculating the characteristic impedance of transmission lines. It should be emphasized that the combination of the equivalent electrodes method and a new variant of the boundary element method can be efficiently implemented in quasi-transverse electromagnetic analysis of transmission lines without loss of accuracy. All results for the characteristic impedance of the observed transmission lines are compared to corresponding ones obtained by the finite-element method.

Analytical-numerical approach for levitation force calculation of a cylindrical bearing with permanent magnets used in an electric meter

Two different approaches of levitation force calculation in electric meters magnetic bearings with two permanent magnets are presented in this paper. The first one is an analytical-numerical method. The results obtained using this method are compared with results calculated numerically by using the 2D-FEM program Opera 13 of Vector Fields. The results are presented in a graphical form.

A Novel Approach to the Positive DC Nonlinear Corona Design

Abstract This article is aimed at proposing one very simple method for electric field and potential distribution determination in the case of large charges at electrodes surfaces when the electric field takes a very high value and induces corona discharges. The method also enables capacitance calculation as well as a dimension of the corona region. By using appropriate analogies, parameters of grounding systems driven by high currents can also be determined.

Analysis of wire antenna structures above lossy homogeneous soil

Characteristics and performance of antennas positioned in the air above lossy half-space are more or less influenced by its electrical parameters. This influence is mathematically expressed by so-called Sommerfelds integrals that are not solvable in a closed form. In this paper, a number of simple approximations will be used for their evaluation. In order to illustrate the range of validity of those approximations, a few practically important antenna structures will be analysed solving the Halléns integral equation and applying the point-matching method. Obtained results will be then discussed and compared to available ones of other authors. Based on presented results, corresponding conclusions will be made.

Interaction magnetic force calculation of radial passive magnetic bearing using magnetization charges and discretization technique

Calculation of the interaction magnetic force between two ring permanent magnets with radial magnetization is presented in the paper. Such configuration corresponds to a radial passive magnetic bearing. The simple and fast analytical approach is used for this calculation based on magnetization charges and discretization technique. The results for interaction magnetic force obtained using proposed approach are compared with finite element method (FEM). The advantage of presented approach is its simplicity and time efficiency since only complete elliptic integrals of the second kind are used and other additional integrations are avoided in this calculation.

Interaction Magnetic Force Calculation of Ring Permanent Magnets Using Ampere's Microscopic Surface Currents and Discretization Technique

Abstract Calculation of the interaction magnetic force between two ring permanent magnets of trapezoidal cross-section and a ring permanent magnet above the infinite linear magnetic plane is presented in this article. The simple and fast analytical approach is used for these calculations based on the distribution of microscopic surface Amperes currents and the discretization technique. The results for the interaction magnetic force obtained using the analytical method and discretization technique are compared with the finite-element method by using FEMM 4.2 software (Meeker, n.d.).

Analysis of a MV XLPE cable termination design with embedded electrodes

Insertion of embedded electrodes (EEs) inside a MV XLPE cable termi- nation strongly affects electric field around the terminati on and accordingly must be carefully considered. In this paper, influence of embedded e lectrodes on voltage distri- bution in some constructions of the 20 kV cable terminations was analyzed. Different options were considered for a specific number of the EEs along the cable insulation surface, taking into account possible effects of floating or grounded EEs, their differ- ent position and separation. In every option, a basic method of stress relieving with resistive layer over the end of semi conducting screen and primary cable insulation was applied. Reference design was a cable termination without EE. Its voltage dis- tribution, total electric field and tangential component we re observed for comparison. The stress relief materials, in the shape of pads or tubes, we re used. Their properties were kept the same in all constructions. Voltage distributi on was monitored, starting from the end of the primary cable insulation in the vicinity of the phase conductor and ending at the cable insulation attached to the semiconducting screen end at ground potential. The different design options were experimentally verified.

Determination of Magnetic Field for Different Shaped Permanent Magnets

The paper presents the magnetic field calculation of permanent magnets, homogeneously magnetized in known direction. Method used in the paper is based on a system of equivalent magnetic dipoles. The results that are obtained using this analytical method are compared with results obtained using FEMLAB software. Magnetic field and magnetic flux density distributions of permanent magnet are shown in the paper.

One Method for Strong Electric Field Reduction at Cable Terminations and their Influence on Environment

Cable terminations and cable joints belong to the most sensitive and the weakest parts of electrical power lines. At the places of cable connecting and ending, the exterior cover is removed, and the radial character of electric field is disturbed. Because of high voltage, the inhomogeneous electric field exists on those parts of the cable, having the highest intensity at the ends of the covers, or screen. Using additional grounded or floating electrodes, it is possible to control and decrease the intensity of the electric field, depending on their position, which has strong influence on the electric field strength. The procedure for determining optimal length and position of the grounded electrode related to the cable end is presented in the paper. The simplest calculation can be carried out using equivalent electrodes method (EEM), and that obtains very high accuracy of the calculated values.