8 results
Search Results
Now showing 1 - 8 of 8
- ItemAnalysis of Arc Processes in Multi-chamber Arrester for Lightning Protection at High-voltage Overhead Power Lines(Praha : Czech Technical University in Prague, Faculty of Electrical Engineering, Department of Physics, 2017) Murashov, I.V.; Frolov, V.Y.; Uhrlandt, D.; Gortschakow, S.; Ivanov, D.V.; Sivaev, A.D.Nowadays multi-chamber arresters are widely distributed as devices of lightning protection of overhead power lines. A mathematical modelling of processes in the discharge chamber of multichamber arrester is necessary to carry out in order to improve its breaking capacity. A three-dimensional mathematical transient model of thermal, gas-dynamic and electromagnetic processes taking place in the discharge chamber of multi-chamber arrester is presented in the article. Basic assumptions, model equations, a computational domain and the boundary conditions are described. Plasma turbulence is taken into account. The results of the calculation i.e. distributions of plasma temperature and overpressure in the discharge chamber at different time points are shown. The analysis of the results was carried out. It is shown that the presence of cavities in the electrodes design promotes electric arc extinction in the discharge chamber of multi-chamber arrester.
- ItemAnalysis of erosion resistance of CuC arcing contacts manufactured by plasma spraying technology(Praha : Czech Technical University in Prague, Faculty of Electrical Engineering, Department of Physics, 2019) Derevyankin, P.; Frolov, V.; Gonzalez, D.; Gortschakow, S.; Methling, R.; Uhrlandt, D.Results of the erosion resistance study of the CuC electrodes manufactured by plasma spraying technology are presented. The diagnostics has have been performed by means of high-speed camera technique and optical emission spectroscopy which has been synchronised with electrical diagnostics. After the load material analyses, namely determination of mass loss and analysis of micro sections, have been done. It has been found that the erosion rate depends on conditions applied for the formation of coating layer, which was deposited either in air or in argon plasma. Furthermore, the erosion rate is significantly lower in the case of air plasma spraying.
- ItemModelling and experimental investigations of DC electric arcs in argon and carbon dioxide(Praha : Czech Technical University in Prague, Faculty of Electrical Engineering, Department of Physics, 2019) Mohsni, C.; Baeva, M.; Franke, S.; Gortschakow, S.; Gonzalez, D.; Araoud, Z.; Charrada, K.In this work an arc model is employed along with electric and spectroscopic measurements to study DC electric arcs in Ar and CO2. The model is aimed at describing the arc and the electrodes. Simulation and experimental results are shown for currents between 150 A and 210 A.
- Item3D analysis of low-voltage gas-filled DC switch using simplified arc model(Praha : Czech Technical University in Prague, Faculty of Electrical Engineering, Department of Physics, 2019) Gortschakow, S.; Gonzalez, D.; Yu, S.; Werner, F.Electro-magnetic simulations have been used for the visualization of distribution of Lorentz force acting on a DC switching arc in low-voltage contactor. A simplified plasma model (black-box model) was applied for the description of arc conductivity. Arc geometry was gained from the high-speed camera images. Influence of arc position, arc current and of external magnetic field has been studied. Results have been compared with optical observations of the arc dynamics.
- ItemDetermination of Cr Density in the Active Phase of a High-current Vacuum Arcs(Praha : Czech Technical University in Prague, Faculty of Electrical Engineering, Department of Physics, 2017) Gortschakow, S.; Khakpour, A.; Popov, S.; Franke, S.; Methling, R.; Uhrlandt, D.Melting and evaporation of the anode surface strongly influence the interruption capability of vacuum circuit breakers, because they lead to injection of atomic vapour into the inter-electrode gap. Determination of the vapour density and its dynamics with respect to different anode phenomena is therefore of great importance. Results of Cr density measurements in a high-current vacuum arc by using broadband absorption spectroscopy are presented. The vapour density of atomic Cr is determined after the formation of anode spots as well as close to the current zero. Cr I resonance lines at 425.43 nm have been used for the analysis. An AC current pulse with maximum value of 7 kA and a frequency of 100 Hz is applied to a vacuum arc between two cylindrical butt electrodes made of CuCr7525 with a diameter of 10 mm. The high-current anode modes are observed by means of high-speed camera imaging. The temporal evolution of the Cr ground state density is presented and discussed.
- ItemEmission Spectroscopy During High-Current Anode Modes in Vacuum Arc(Praha : Czech Technical University in Prague, Faculty of Electrical Engineering, Department of Physics, 2017) Khakpour, A.; Methling, R.; Franke, S.; Gortschakow, S.; Uhrlandt, D.A vacuum interrupter reaches its interruption limit once high-current anode phenomena occur. High-current anode modes lead to an increase of the anode surface temperature and an increased generation of metal vapor, which may result in a weakening of the dielectric recovery strength after current zero. In this work, different discharge modes in a vacuum arc for AC 50 Hz including diffuse, footpoint, anode spot type 1 and type 2, and anode plume are investigated. Electrodes made of CuCr7525 with diameter of 10 mm are used. The final gap length is about 20 mm. Time and space resolved optical emission spectroscopy is used to examine the temporal and spatial distribution of atomic and ionic copper lines. The distribution of atomic and ionic lines parallel and perpendicular to the anode surface is investigated. Radiator density is also determined for CuI, CuII, and CuIII near the anode surface.
- ItemAdvanced Approach for Radiation Transport Description in 3D Collisional-radiative Models(Praha : Czech Technical University in Prague, Faculty of Electrical Engineering, Department of Physics, 2017) Kalanov, D.; Golubovskii, Y.B.; Uhrlandt, D.; Gortschakow, S.The description of radiation transport phenomena in the frames of collisional-radiative models requires the solution of Holstein-Biberman equation. An advanced solutuion method for 3D plasma obejcts is proposed. The method is applicable for various line contours in a wide range of absorption coefficients. Developed approach is based on discretization of the arbitrary plasma volume on a Cartesian voxel grid. Transport of photons between the cells is computed using the ray traversal algorithm by Amanatides [1]. Solution of the particle balance equations with computed in advance radiative transfer matrix is demonstrated for various typical arc shapes, like e.g. free-burning arc and cylindric arc. Results are compared with corresponding calculations using previously developed approaches. As the method is suited for finite geometries and allows for a strict solution of the radiation transport equation, applicability ranges of previous approximations can be specified.
- ItemInfluence of resonance radiation transport on chemical equilibrium in an argon arc(Praha : Czech Technical University in Prague, Faculty of Electrical Engineering, Department of Physics, 2019) Gortschakow, S.; Kalanov, D.; Golubovskii, Yu.Deviations from chemical equilibrium in argon arc plasma are analysed by means of collisional-radiative model. Corresponding comprehensive kinetic scheme has been developed and applied form study of free-burning arc at the conditions typical for welding applications. While the natural lifetime have been used for radiation emitted from highly excited argon states, the resonance radiation was described taking into account the radiation transport effects. Resulting spatial distributions of excited argon atoms are compared for the cases of LTE and two-temperature plasma using different approaches for the description of the resonance radiation transport.