Plasma Physics and Technology journal

Plasma Physics and Technology Journal
Volume 2 (2015)

Number 1

An Experimental Study of the Photoelectron Work Function Change of Silver-Based Contacts Induced by Arcing in Air

Akbi M. ^1,2,3

¹ Department of Physics, National Preparatory School for Engineering Studies (ENPEI), B.P. 05, Rouiba, DZ-16012, Algiers, Algeria
²Department of Physics, Faculty of Sciences, University of Boumerdes (UMBB), Independence Avenue, DZ-35000, Boumerdes, Algeria
³Laboratoire “Arc Electrique et Plasmas Thermiques”, CNRS, UPRES-A 6069, 24, Avenue des Landais, F-63177, Aubière Cedex, France

The influence of industrial conditioning (polishing, mechanical shocks and electrical arcs in air) on the electron emission and morphology of contact pastilles made of pure silver [Ag (99.999%)], silver–nickel alloy [Ag–Ni (60/40)], silver–tungsten alloy [Ag–W (50/50)], and silver–tungsten carbide [Ag–WC (50/50)] was investigated. The electronic emission behavior of pure silver Ag and silver-metal alloys (Ag-Me), for both virgin and arced electrical contacts, were studied. Contacts were mounted in a contactor working repeatedly on air (laboratory atmosphere). When submitted to 500 opening electric arcs, the electron work function of an electromechanically conditioned contact Ag-Ni (60/40), measured photoelectrically by using Fowler’s method of isothermal curves, is φ = (4.50 ± 003) eV at room temperature, while for virgin Ag contacts, it was (4.30 ± 003) eV. The in-crease in the electron work function (EWF) is due to the progressive inclusion of silver oxide in the Ag contact surface during arcing in air.
The conditioned (500 arcs) silver-metal alloys studied in this work exhibit the same electronic emission behavior, namely arcing in air increases their EWF. We demonstrated that the electromechanical conditioning by successive electrical arcs affects the surface characteristics such as microstructure, roughness and photoelectron work function. The paper addresses a breakdown of a vacuum gap containing an insulator sputtered with electrode material. A mechanism for development of repeated discharges in the given electrode configuration is described.

Keywords: electron work function, photoemission, Fowler’s method, contact materials, electrical arcs, cathode phenomena

* * *

Arc Simulation in Low Voltage Switching Devices, a Case Study

Bianchetti R.¹, Adami A.², Fagiano L.¹, Gati R.¹, Hofstetter L.¹

¹ABB Schweiz AG, Corporate Research, CH-5405 Baden, Switzerland
²ABB S.p.A. – ABB SACE Division, IT-24123 Bergamo, Italy

Arc simulations are becoming a valuable tool in the development of low voltage switching devices. Sim-ulations reveal physical quantities that are experimentally not accessible and help in the investigation of the underlying phenomena. However, the strong interaction between different processes and the intrinsic multi-scale nature of the problem, both in time and space, pose great challenges to accurate and efficient simulations. At ABB Corporate Research, we developed a simulation tool capable of simulating the be-havior of low voltage switchgear. To verify the accuracy and predictive capability of our platform, we validate the simulations by comparing their results with available experimental findings. After describing the tool, we provide here evidence of the good agreement between measured and simulated data on several commercial ABB devices.

Keywords: arc, simulation, multiphysics, air switching

* * *

Investigation of the Process of Microwave Plasma Ashing of Photoresist Films from Semiconductor Wafers Using the Method of Optical Emission Spectroscopy

Bordusau S. V., Madveika S. I., Lushakova M. S.

Belarusian State University of Informatics and Radioelectronics, P.Brovki, 6, 220013, Minsk, Belarus

The results of the analysis of photoresist protection coating removal dynamics in oxygen microwave plasma as well as the character of light emission intensity change of spectral line O1 (λ=844,6 nm), used to control the removal of photoresist in case of processing a big number of silicon wafers, are presented. The obtained results enable supplementing phenomenological model of plasmachemical destruction of photoresist films in the volume of oxygen microwave plasma.

Keywords: plasma, microwave discharge, photoresist, films, ashing

* * *

Validation of a Non-invasive Measuring Method to Determine the Arc Position of an Axially Blown Switching Arc

Forschelen M., Nikolic P. G., Stoffels M., Schnettler A.

Institute for High Voltage Technology, RWTH Aachen University, Schinkelstrasse 2, 52056 Aachen, Germany

Today’s research on circuit breaker concepts for alternative insulation and quenching gases is focused on the understanding of the physical processes during a switching process as well as the interaction of the blow gas flow and the switching arc. In order to determine these influences a non-invasive measuring method is established which allows the determination of the spatial arc resistance distribution of an axially blown switching arc to gain a deeper understanding of the cooling processes. In addition, this system is capable of detecting the position of the switching arc by means of trilateration with a measurement system consisting of multiple capacitive field probes. The measurement system is adapted to a laval nozzle geometry and investigations in nitrogen are performed. The results of these investigations are compared to basic optical investigations on switching arcs within this laval nozzle to validate the applicability of the assumptions made for the position determination.

Keywords: non-invasive diagnostics, arc position, arc resistance distribution, optical investigations

* * *

Optical and Tribological Properties of PVD/CVD Diamond-like Carbon Films

Golosov D. A., Melnikov S. N., Zavadski S. M., Ermolenko M. V.

Belarusian State University of Informatics and Radioelectronics, 6 P.Brovka str., 220013 Minsk, Belarus

The optical and tribological properties of diamond-like carbon (DLC) films deposited by the combination of magnetron sputtering of graphite and plasmochemical dissociation of methane were studied. It was established that at methane concentration in the gas mixture Ar/CH4 at about 5–10 % the formation of DLC films with refraction index n ≥ 2.0, microhardness larger than 1000 HK and friction coefficient of 0.06–0.08 becomes possible.

Keywords: diamond-like carbon, magnetron sputtering, methane dissociation, refractive index, friction coefficient, microhardness

* * *

Effect of Resonance Radiation Trapping on the Excited State Densities in Free-Burning Arc Plasmas

Gorchakov S.¹, Baeva M.¹, Golubovskii Yu.², Kalanov D.², Uhrlandt D.¹

¹ Leibniz Institute for Plasma Science and Technology, Felix-Hausdorff-Str.2 17489 Greifswald, Germany
² Saint-Petersburg State University, Ulyanovskaya st.3 198504 St.Petersburg, Russia

Modern arc models takes into account collisional-radiative schemes for better agreement with experiment. Radiation transport phenomena play an important role in redistribution of excited species densities. Influence of resonance radiation transport on spatial distribution of excited atoms in argon arc plasma was studied by numerical model. Solution of the Holstein-Biberman equation was based on the matrix method. Results are compared with conventional effective lifetime approach.

Keywords: free-burning arc, radiation transport, excited species, argon plasma

* * *

Arc Extinguishing in the DC and Photovoltaic Networks

Huttner L., Jurcacko L., Valent F., Vary M.

Slovak University of Technology in Bratislava, Faculty of Electrical Engineering and Information Technology,
Ilkovičova 3, 812 19 Bratislava, Slovakia

In this contribution the various behaviors of arc voltage created with extinguishing system and the influence on current and energy released behavior in the extinction system are theoretically and experimentally analyzed. In the area of photovoltaic it represents the increase of working voltages up to 1500 V. In the experimental part the oscilogrammes of DC current interruption with various extinction systems are presented. For the reliability of current interruption mainly in the photovoltaic (PV) networks it is necessary to dedicate increased attention to development and design of switch and protection gears.

Keywords: DC current, extinguishing chamber, PV source, switchgear

* * *

The Modeling and Analysis of the Current Density in Current Gauges and Contact Syste

Kolimas L.¹, Kulas S.²

¹ Warsaw University of Technology, Institute of Electrical Power Engineering, Warsaw, Poland
² Military University of Technology, Faculty of Electronics, Warsaw, Poland

Transmission lines and contact assemblies adapted for conducting considerable values of constant and momentary current ratings are usually built as the set of many isolated parallel paths, in addition spaces between electric contacts are little compared with their width. Ensuring the big power-driven load capacity to a maximum is aimed at it. In these types of paths flow of the electricity through each of them is, how it could be expected, uneven. It is an effect of the occurrence of skin effect and an effect of closer acquaintance. So, we cannot increase their power-driven load capacity proportionally to the amount of transmission lines. Inductances are different, depending on the place of the path. The following calculations are supposed to explain and to depict, which from paths (in case of contact assemblies – electric contacts) will be mostly exposed at the flow of the electricity, as well as will let the resistance understand the relation of the contact effect of the material and the structure of joints.

Keywords: contact systems, current gauges, current density

* * *

Breakdown Mechanism in Transformer Oil ITO 100

Kudelcik J.¹, Varačka L.¹, Poljak S.²

¹ Departement of physics, Faculty of Electrical Engineering
² Department of Design and Mechanical Element, Faculty of Mechanical Engineering
^1,2 University of Žilina, Univerzitná 1, 010 26 Žilina, Slovakia

The DC breakdown characteristics of dielectric liquid – transformer oil were measured. The experimental results showed that the breakdown voltage in transformer oil increases with the external pressure. This pressure dependence indicated the involvement of gas phase process during the development of stage of the prebreakdown process. The initial state of breakdown development on the basis of bubble theory was explained. Using the Braginskii-Martin's analytical model parameters of breakdown channel were calcu-lated. Development of vapor channel after breakdown was recorded by high speed camera.

Keywords: streamer, breakdown, arc channel, temperature

* * *

Measurement of Electric Conductivity of Hot Gas in a SF6-circuit Breaker Interrupting Fault Currents

Leu C.¹, Gossel S.¹, Birle M.¹, Reichert F.²

¹ Technische Universität Ilmenau, Research Unit High-Voltage Technologies, Ilmenau, 98693, Germany
² Siemens AG, E T HP CB R&D ENG 1, Berlin, 13629, Germany

The realization of a new measurement method to determine electric conductivity of hot SF₆-gas during interruption fault currents in an original self-blast circuit breaker is presented. The method is based on evaluation of phase shift between sinusoidal kHz-high voltage and current, applied on a sensor. This needs a kHz-resonance voltage generator and adapted sensors as a part of an electromagnetic shielded measurement system to determine time dependent electric conductivity with high resolution.

Keywords: SF₆-circuit breaker, hot gas flow, electric conductivity

* * *

A Review on Electrical Performances of Nanocrystalline Contact Materials

Li Z., Huang J., Yang X., Wei J.

State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology,1037 Luoyu Road, Wuhan 430074, China

Nano technology is one of new areas in material developments, and nanocrystalline contact materials, such as CuCr and AgSnO2, may have different electrical performances from microcrystalline contacts. A review is made in this paper to compare performance differences between nanocrystalline and microcrystalline contact materials, including arcing durations, welding behaviors, chopping currents, breakdown voltages, and breaking capacities.

Keywords: welding, electrical contact, arc duration

* * *

Arc Simulation at Shunt-Reactor Switching in H.V. Circuit Breakers

Madarasz Gy. A., Szabo K., Kiraly L.

Hyundai Technology Center Hungary, Hermina u 22, 1146 Budapest, Hungary

High energy re-ignitions occur in h.v. circuit breakers, when interrupting shunt-reactor currents. The escalating high frequency over-voltages, which are proportional to the arcing time, are stressful both to the reactor and the circuit breakers. We simulated the electric, thermal and flow field inside the thermal chamber and determined the reduced electric field distribution. Analysing the simulation results the main factors to improve the shunt-reactor breaking capacity are demonstrated.

Keywords: arc simulation, circuit breaker, shunt reactor switching

* * *

Study of Nitrogen Atom Recombination by Optical Emission Spectroscopy

Mazánkova V.¹, Trunec D.², Krčma F.¹

¹ Faculty of Chemistry, Brno University of Technology, Purkyňova 118, Brno 612 00, Czech Republic
² Masaryk University, Kotlarska 2, 611 37 Brno, Czech Republic

The reaction kinetics in nitrogen flowing afterglow was studied by optical emission spectroscopy. The DC flowing post-discharge in pure nitrogen was created in a quartz tube at the total gas pressure of 1000 Pa. The optical emission spectra were measured along the flow tube. It was found that N atoms are the most important particles in the late nitrogen afterglow. In order to explain the decrease of N atom concentration, it was also necessary to include the surface recombination of N atoms to the model.

Keywords: optical emission spectroscopy, nitrogen afterglow, surface recombination coefficient

* * *

Phenomena in Complex (Dusty) Plasma Studied under Microgravity Conditions

Molotkov V. I.¹, Lipaev A. M.¹, Zhukhovitskii D. I.¹, Naumkin V. N.¹, Thomas H. M.², Khrapak S. A.^1,2, Huber P.²

¹ Joint Institute of High Temperatures, Russian Academy of Sciences, Izhorskaya 13, Bd. 2, 125412 Moscow, Russia,
² Research Group Complex Plasma, DLR, Oberpfaffenhofen, 82234 Wessling, Germany

Complex (dusty) plasmas are composed of weakly ionized gas and charged microparticles and represent the plasma state of soft matter. The investigations which are not available on ground have been per-formed onboard the International Space Station (ISS) with the help of the “Plasma Crystal-3 Plus” (PK-3 Plus) laboratory. A number of interesting phenomena has been observed. The phase transition from iso-tropic plasma into electrorheological plasma was initiated. The crystal-liquid phase transition was ob-tained in large 3D isotropic dusty plasma. The slow compression of the dust particle subsystem has been investigated.

Keywords: complex plasma, plasma crystals, solid-liquid transitions, microgravity

* * *

Development of Prototype Low-cost and High-strength Fault Current Interrupting Arcing Horns for 77 kV Overhead Transmission Lines

Ohtaka T. ¹, Iwata M. ¹, Goshima H.¹, Awazu H.², Omote T.², Nakanishi T.³, Kamimura K.³, Uehara M.³

¹ Central Research Institute of Electric Power Industry, 2-6-1 Nagasaka, Yokosuka-shi, Kanagawa 240-0196, Japan
² Kansai Electric Power Co., Inc., 6-2-27 Nakanoshima, Kita-ku, Osaka-shi, Osaka 530-6691, Japan ² Nippon Katan Co., Ltd., 13-1 Isoshimaminamimachi, Hirakata-shi, Osaka 573-1020, Japan

Fault Current Interrupting Arcing Horns (FCIAH) are newly designed arcing horns installed on transmis-sion line towers as a countermeasure against lightning damage that greatly contribute to reducing power interruption by interrupting fault current independently within an AC cycle. This paper describes the de-velopment of two new prototype FCIAH for further cost reduction and strength enhancement, using computational fluid dynamics and short-circuit tests.

Keywords: Fault Current Interrupting Arcing Horns, lightning, arc, computational fluid dynamics

* * *

CFD Arc Simulation of a Switching-off Process in a Model Chamber

Petchanka A.¹, Reichert F.¹, Methling F.², Franke S.²

¹ Siemens AG, EM HP CB R&D EN, Nonnedammallee 104, 13629 Berlin, Germany
² Leibniz Institute for Plasma Science and Technology (INP Greifswald), Felix-Hausdorff-Str. 2, 17489 Greifswald, Germany

This paper deals with the investigation of the switching arc process in a model chamber by CFD arc simulation. A transient axisymmetric model based on the @Fluent software is used. The applied arc model considers electromagnetic phenomena, radiative transfer, ablation of PTFE parts and pin motion as well. The influence of the boundary conditions for the solution of the current continuity equation is highlighted. The obtained results are validated by measurements on the model chamber.

Keywords: CFD arc simulation, model chamber, switching-off process

* * *

Development of a Plasma Solver for Surge Protective Devices using Spark Gap Technology

Sander C.¹, Rüther J.², Kurrat M.²

¹ PHOENIX CONTACT GmbH & Co. KG, Flachsmarktstraße 8, D-32825 Blomberg, Germany
² Technische Universität Braunschweig, Institute for High Voltage Technology and Electrical Power Sys-tems, Schleinitzstraße 23, 38106 Braunschweig, Germany

In this article we present the development of a single-fluid plasma model using the open-source CFD-based modelling framework OpenFOAM for the simulation of surge protective devices. The model uses a pressure based flow solver and supports the use of common radiation models such as the P1 model. Empirical models for electrode sheaths can be used and coupling the simulation to external circuits is possible. Some initial results are presented and compared with high-speed camera recordings.

Keywords: spark gap, simulation, plasma, arc, lightning, surge protective device

* * *

Modelling of Intensively Blasted Electric Arc

Senk J., Jakubova I., Laznickova I.

Faculty of Electrical Engineering and Communication, Brno University of Technology, Technicka 12, 616 00 Brno, Czech Republic

The paper deals with a simplified model of an intensively blasted electric arc burning in the anode chan-nel of an arc heater. The model is based on the energy conservation law, continuity equation and Ohm’s law. For computation, transport and thermodynamic properties of working medium and real experimental results describing the external manifestation of the arc are necessary. Many experimental data have been collected during numerous experiments made out with a modular arc heater operated under various ex-perimental conditions, each experiment being characterized by the arc current, voltage, the sort and flow rate of working gas, and the flow rates and temperatures of cooling water in individual segments of the device. In the presented model a rectangular temperature profile of the arc is used. A dependency of the arc column radius rA on the distance from the cathode is prescribed and parameters of the function rA(z) are estimated using the total power balance at the output cross-section of the anode channel. Special at-tention is paid to the region near the beginning. The dependencies of the arc temperature and electric field intensity on the distance from the cathode are calculated and iterations are stopped if the sums of computed increments agree with the measured values. Computed dependencies are given in diagrams and discussed.

Keywords: intensively blasted electric arc, arc heater, argon, modelling

* * *

Deposition of Fluorocarbon Plasma Polymer Nanoparticles and their Basic Properties

Serov A.^1,2, Choukourov A.¹, Artemenko A.¹, Kuzminova A.¹, Biederman H.¹, Hrabovsky M.²

¹ Department of Macromolecular Physics, Charles University in Prague, V Holesovickach 2, Prague, Czech Republic
² Thermal Plasma Department, Institute of Plasma Physics, Za Slovankou 3, Prague, Czech Repub-licLaboratorio de Espectroscopia, Instituto de Ciencias Fisicas, Universidad Nacional Autonoma de Mexico, A.P. 48 3, C.P. 62251, Cuernavaca, Morelos, Mexico

Fluorocarbon plasma polymer nanoparticles have been fabricated using gas aggregation cluster source (GAS) equipped with a planar magnetron with PTFE target. A beam of nanoparticles 20 – 200 nm in diameter was generated. Fluorocarbon nanoparticle films have shown very good water repellent properties. Films immersed in ethanol for two hours exhibited excellent stability that was also good in case of water. Measurements using a deflection system showed the presence of both neutral and charged nanoparticles.

Keywords: poly(tetrafluoroethylene), magnetron sputtering, plasma polymerization, superhydrophobic

* * *

Measurements of Gas Pressure into the MV Arc Plasma Environment

Smugala D.¹, Oramus P.¹, Krysztofiak P.¹, Bonk M.², Piekarski P.³, Domurad Z.³, Kaczmarczyk T.⁴

¹ ABB Corporate Research Centre, Starowislna 13A, 31-038 Krakow, Poland
² AGH University of Science, Mickiewicza 30, Krakow, Poland ³ ABB MV Products Technology Centre, Leszno 59, Przasnysz, Poland ⁴ Institute of Power Engineering, Mory 8, Warsaw, Poland

Current interrupters equipped with arc quenching system based on combination of forced air flow and gassing material were the object of the research described in this paper. Arc quenching gas pressure inside the extinguishing chamber in direct vicinity of plasma arc was recorded by means of developed measurement system resistant for heavy duty conditions existent inside the chamber during breaking. Gas pressure was estimated for several values of load current at 12/24 kV source voltage.

Keywords: arc quenching, measurement, gas pressure, arc energy, arc plasma

* * *

Air Flow Measurements during Medium-Voltage Load Current Interruptions

Stoa-Aanensen N. S.^1,2, Runde M.²

¹ Norwegian University of Science and Technology, Trondheim 7491, Norway
² SINTEF Energy Research, Trondheim 7465, Norway

Air has been considered a good alternative to SF₆ as arc quenching medium for load break switchgear at medium voltage ratings. In this work, the air flow characteristics and influence from the electric arc have been studied for typical currents and over-pressures. The cooling air velocity is typically in the range 150 - 200 m/s and thus well below supersonic speed. The arc and the surrounding hot air severely affect the air flow pattern by causing clogging in the contact and nozzle region.

Keywords: load break switch, switchgear, medium voltage, arc, air flow, thermal interruption

* * *

The Influence of Admixtures on the Composition of Products by Nitrogen-Methane Atmospheric Glow Discharge

Torokova L.^1,2, Mazankova V.¹, Krcma F.¹, Mason N. J.², Matejcik S.³

¹ Faculty of Chemistry, Brno University of Technology, Purkynova 119, 612 00, Brno, Czech Republic
² Department of Physics and Astronomy, Open University, Walton Hall, Milton Keynes MK7 6AA, UK
³ Department of Experimental Physics, Comenius University, Mlynska dolina F-2, 842 48 Bratislava, Slovakia

This work extends our experimentally studies with simulation of Titan’s atmosphere by atmospheric glow discharge. This work is devoted to estimate the influence of CO₂ and/or CO on reactivity in the Titan’s atmosphere. The exploration of planetary atmosphere is being advanced by the exciting results of the Cassin-Huygens mission to Saturn and Titan, its most famous moon. Most of the studies were mainly interested in the reactivity of the N₂-CH₄ gaseous mixture and with the primary products of reactions, but the atmosphere of Titan also contains oxygenated volatile species.

Keywords: Titan’s atmosphere, atmospheric glow discharge, FTIR spectroscopy

* * *

Calculation of the Heat Affected Zone Coupled with the Arc Simulation in Tig Welding Process Considering the Marangoni Effect

Toropchin A.¹, Frolov V.¹, Pipa A. V.², Uhrlandt D.²

¹ Peter the Great St Petersburg Polytechnic University, 29 Polytechnicheskaya, 195251 Saint-Petersburg, Russia
² 2Leibniz-Institute for Plasma Science and Technology (INP Greifswald), Felix-Hausdorff-Str. 2, 17489 Greifswald, Germany

The present article is focused on a tungsten inert gas (TIG) welding process in two operation regimes, a normal and a constricted one. A computational model is applied for simulations of the liquid weld pool and the heat-affected zone of the workpiece coupled with a simulation of the welding arc. Welding experiments are used for model validation. Temperature profiles obtained from high-speed images with spectral filters correspond well with arc simulation results for both operation regimes.

Keywords: tungsten inert gas welding, constricted arc, arc simulation, weld pool

* * *

Peculiarities of Interaction of Electric Arc Plasma and Composite Electrodes’ Working Surface

Veklich A.¹, Lebid A.¹, Minakova R.², Kryachko L.², Grechanyuk N.²

¹ Taras Shevchenko National University of Kyiv, 64/13, Volodymyrska str., Kyiv, Ukraine
² Frantsevich Institute for Problems of Materials Science NAS of Ukraine, 3, Krzhizhanovsky str., Kyiv, Ukraine

The aim of this work is complex investigations of interaction between electric arc discharge plasma and Cu-Mo composite electrodes’ working surface. The destructions of working layer of such electrodes, caused by discharge plasma influence, were studied. The mutual correlation of plasma properties and destruction behavior of electrodes surface was found.

Keywords: composite materials, electric arc plasma, switching arcs

* * *

Multi-Spark Plasma Actuator for Flow Control

Veklich A., Boretskij V., Fesenko S., Lebid A.

Taras Shevchenko National University of Kyiv, 64/13, Volodymyrska str., 01601 Kyiv, Ukraine

Plasma properties of spark discharge at multi-electrode actuator, designed for flow control, are discussed. Optical emission spectroscopy is used in investigation of such plasma. No effect of metal particles eroded from electrodes on properties of spark discharge plasma was observed. A method of excitation temperature determination by reconstructing of experimentally registered spectrum of the spark was developed.

Keywords: spark plasma, optical spectroscopy, spectrum modelling

* * *

Investigation of the Influence of Plastic Evaporation on Pressure Rise due to Fault Arcs in Electrical Installations

Wetzeler S., Pietsch G. J.

Institute for High Voltage Technology, RWTH Aachen University, Schinkelstr. 2, 52056 Aachen, Germany

Internal arcs in electrical installations cause a sudden pressure rise due to heating of the gas surrounding the arc. The pressure rise may endanger personnel, the electrical installation and even the switchgear building. Based on the need to design switchgear more compact, plastic materials are used. The interaction of the arc with these materials releases gases by evaporation and thereby influences the pressure rise within the installation as well as the energy balance of the arc. In order to analyse these effects in detail, some commonly used plastics are exposed to a high current arc. In this contribution the pressure development in a closed vessel equipped with different plastic materials, their mass losses and the portion of electrical energy causing overpressure, known as thermal transfer coefficient or k_p–factor, are determined at three values of the filling pressure of the vessel. The plastic materials under investigation are epoxy, polyamide 6.6, polybutyleneterephtalate, polycarbonate and silicone rubber. With the information provided, the influence of the different plastics on pressure development can be predicted.

Keywords: internal arcs, plastic evaporation, pressure calculations

* * *

Volume 2, Number 2

Detailed Investigation of Breakdown Prediction Models for High Voltage Circuit Breakers

Aded Hussein S., Vassilev A., Joly A., Robin-Jouan Ph.

ALSTOM Grid - High Voltage Switchgear Research Center ARC 130 rue L. BLUM 69611 Villeurbanne France

Although studied for several decades, detailed knowledge on the leader mechanism conducting to a dielectric breakdown seems to be still insufficient. For this reason, based on home-made 2D-Euler CFD code, the present study handles the pressure and temperature as controlling parameters to consider for the efficient prediction of the dielectric breakdown. Moreover, it presents the limits of the suggested theoretical approach. This theoretical and numerical investigation is correlated with corresponding power test results on HV mock-ups.

Keywords: numerical simulation, restrike mechanism, breakdown criterion, parametric analysis

* * *

Influence of the Upstream Parameters on the Thermal Limit for HV Gas-Blast Devices

Averyanova S., Tonkonogov E.

St. Petersburg Polytechnic University, Electrical Engineering and Power Industry Department St. Petersburg, Russia

Increasing the intensity of the interaction between switching arc and gas flow can lead to increasing the HV gas-blast devices thermal interruption ability. The numerical investigations of the two-pressure monoflow arc-extinguishing chamber equip with open heating volume are discussed. Numerical simulation and experimental data have shown that this chamber changes the gas parameters in the upstream region, so the thermal interruption ability increases.

Keywords: interruption ability, upstream region, turbulence, numerical simulation

* * *

The Rotating Gliding Discharge in Quartz Tube and Open Half-Space at Atmospheric Pressure

Chernyak V. Ya., Chernolutsky D. L., Kolgan V. V., Martysh Eu. V., Solomenko Ol. V., Nedybaliuk O. A., Luskin A. E., Solomenko Ok. V., Iukhymenko V. V., Shapoval V. A.

Taras Shevchenko National University of Kyiv, Faculty of Radio Physics, Electronics and Computer Systems. Ave academic Glushkov 4 g, Kyiv, Ukraine

Rotating sliding discharge (RGD) was investigated into limited volume and open half-space. The cur-rent-voltage characteristics of the discharge and its specifications are described. The results of optical research: photos and emission spectra of the discharge are presented.

Keywords: RGD, plasma, plasma chemistry, erosion

* * *

Arc Fault Protection System in Low-Voltage Installations for Protecting Installations and Persons

Ehrhardt A.

DEHN + SÖHNE GmbH + Co.KG., Hans-Dehn-Straße 1, 92318 Neumarkt, Germany

Overcurrent protective devices are often not sufficient to protect installations and persons from the ef-fects of arc faults. Fast active protective devices, which limit the arc duration to some milliseconds, pro-vide significantly increased protection. This article deals with the design of and requirements on such an active protection system, which consists of an arc detection device and a short-circuiter. Both fixed in-stallation and a mobile arrangement of the system will be presented.

Keywords: arc fault, arc detection, short-circuiter, protection of installations, live working

* * *

Plasma Injectors Based on Rotating Gliding Discharge with Reverse Vortex Flow with Liquid Electrode

Fedirchyk I.¹, Nedybaliuk O.¹, Chernyak V.¹, Liptuga A.²

¹ Taras Shevchenko National University of Kyiv, 64/13, Volodymyrska Street, 01601, Kyiv, Ukraine
² V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine, 41, pr. Nauki, 03028, Kyiv, Ukraine

The researched plasma-liquid system was developed to create discharge that is compliant with industrial requirements. Current-voltage characteristics of discharge and their dependence on interelectrode dis-tance are obtained. The main components of plasma are presented based on spectroscopy results. Meas-ured electron, vibrational and rotational temperatures prove that system is able to generate non-equilibrium discharge plasma at atmospheric pressure without severe electrode erosion.

Keywords: plasma catalysis, rotating gliding discharge, plasma injector, liquid electrode

* * *

Special Aspects of DC Air Plasma Torch’s Operating Modes under Turbulent Flow Conditions

Frolov V., Murashov I., Ivanov D.

Peter the Great St. Petersburg Polytechnical University, 29 Polytechnicheskaya, 195251 Saint-Petersburg, Russia

The article is dedicated to the analysis of plasma flow turbulization processes inside DC air plasma torches. The influence of plasma torch’s arc current and plasma gas flow rate on plasma flow turbulization inside the torch channel is described. Also, measurements of voltage fluctuation due to motion of point of arc attachment are presented in the article. The mathematical model for the analysis of arc processes inside and outside of plasma torches is developed.

Keywords: plasma torch, spraying technology, turbulence

* * *

The Device for Dynamic Matching of the E-type Discharge Plasma System and Output Tract of Electric Pulses Generator

Godun D. V., Bordusau S. V., Dostanko A. P.

Belarusian State University of Informatics and Radioelectronics, P.Brovki, 6, 220013, Minsk, Belarus

To reduce the reactivity of a glow pulse discharge, the device for stepwise matching of the communica-tion channel of the power stage of electric pulses generator exciting plasma and the plasma discharge as a dynamic load was developed and tested. The peculiarity of this device is the use of a wide range soft-ware-controlled inductive element. The use of mixed analog and digital units circuitry provides stable regulation of inductance from 600 μH to 20 mH. Experimental testing of the device with the E-type dis-charge system at frequencies from 5 kHz to 60 kHz showed a decrease of the phase shift between the current pulses and the discharge voltage and the reduction of the spurious emissions on power pulses tra-jectories. It makes possible to increase the energy efficiency of plasma process and reliability of the op-eration of pulse generator with plasma as a load.

Keywords: plasma, electric generator, matching

* * *

Influence of Copper Vapor on Dielectric Properties of Hot CO2 at Different Pressures from 0.4 MPa to 0.8 MPa

Guo X.¹, Li X.¹, Zhao H.¹, Jia S.¹, Murphy A. B.²

¹ State key laboratory of electrical insulation and power equipment, Xi’an Jiaotong University, No. 28 XianNing West Road, Xi’an, Shaanxi Province 710049, China
² CSIRO Manufacturing Flagship, PO Box 218, Lindfield NSW 2070, Australia

The influence of copper vapor on dielectric properties hot CO₂ at different pressures has been analyzed in this paper. By solving the Boltzmann equation, the electron energy distribution functions and the critical reduced electric field strength (E/N)_cr were obtained. The results indicate that copper markedly reduces (E/N)_cr of CO₂-Cu gas mixtures because of copper's large ionization cross section. Additionally, increasing the gas pressure effectively dellays the pick temperature of(E/N)_cr.

Keywords: copper vapor, CO₂, dielectric properties, Boltzmann equation

* * *

Enthalpy Probe Diagnostics of Steam/Argon Plasma Jet

Hlina M.^1,2, Hrabovsky M.¹

¹ Institute of Plasma Physics AS CR, v.v.i, Za Slovankou 1782/3, CZ-182 00 Prague 8, Czech Republic
² Charles Univ Prague, Dept Analyt Chem, Albertov 6, CZ-12843 Prague 2, Czech Republic

DC plasma torch with argon/water stabilization features extreme properties of the exiting plasma jet. The plasma mass flow rate is very low while the temperature reaches very high values. Plasma properties were measured by enthalpy probe connected to a mass spectrometer. The measurements of enthalpy, temperature, density and dynamic pressure were carried out for three different arc currents and at atmos-pheric pressure. The dependences of plasma characteristics on arc current were shown.

Keywords: enthalpy probe, thermal plasma, plasma diagnostics

* * *

Optimization of 3-band Mean Absorption Coefficients

Kloc P., Aubrecht V., Bartlova M., Coufal O.

1Centre for Research and Utilization of Renewable Energy, FEEC, Brno University of Technology, Technicka 10, Brno, Czech Republic

In this paper we present a process for mean absorption coefficient optimal band selection applied to the 3-band model of radiation in an air electrical arc. For fixed temperature, the divergence of radiation flux in an infinite cylindrical plasma column is calculated using spectrally resolved absorption coefficient and serves as a reference value. Optimization process is used to properly select the bands of 3-band mean absorption approximation using both unmodified and limited Planck mean absorption coefficient. The ac-curacy of aforementioned two approximation methods is evaluated.

Keywords: radiation transfer, mean absorption coefficient, Planck mean, divergence of radiation flux

* * *

Investigation of a Multi-Chamber System for Lightning Protection at Overhead Power Lines

Kozakov R.¹, Khakpour A.¹, Gorchakov S.¹, Uhrlandt D.¹, Ivanov D.², Murashov I.², Podporkin G.³, Frolov V.²

¹ Leibniz Institute for Plasma Science and Technology (INP Greifswald), Felix-Hausdorff-Str. 2, 17489 Greifswald, Germany
² Peter the Great St. Petersburg Polytechnical University, 29 Polytechnicheskaya, 195251 Saint-Petersburg, Russia
³ Streamer, Electric Company Inc., Office 17N, 147 Nevsky Prospect, Saint-Petersburg 191024 Russia

A multi-chamber system with composite electrodes fitted into silicone rubber has been recently proposed for lightning protection of power lines. The arc extinction during a current pulse in the arc chamber has been studied. Optical emission spectroscopy and high speed imaging used in experiments allowed to es-timate plasma temperature and velocity of the jet. Erosion coefficients for electrode materials were esti-mated. Investigations of different materials of the arc chamber were carried out.

Keywords: lightning protection, arc extinction, optical emission spectroscopy, arc temperature

* * *

Theoretical Analysis of Low Vacuum Microwave Discharge Exciting and Maintaining Conditions in Resonator Type Plasmatron

Madveika S. I., Bordusau S. V.

Belarusian State University of Informatics and Radioelectronics, P.Brovki, 6, 220013,Minsk, Belarus

The efficiency of a cavity microwave resonator using for getting large volume (more than 4000 cm³) low vacuum plasma for group treatment of products in the microelectronics technology has been evaluated. The results showed that the value of electric field breakdown intensity about E0 ≈ 200 V/cm in a resonator system for low vacuum can be already achieved at a microwave power higher than 50 W. The conditions of preserving resonating properties at exciting plasma with a volume of 9000 cm³ in resonator and in case of placing a various number of silicon wafers in the microwave discharge have been analyzed.

Keywords: microwave plasma, resonator, waveguide

* * *

Measurement of Copper Vapors in Water-Argon Thermal Plasma Jet

Maslani A., Sember V., Hrabovsky M.

Institute of Plasma Physics AS CR v.v.i., Za Slovankou 3, 18200 Prague, Czech Republic

Plasma jet generated by water-argon plasma torch is enriched by copper evaporated from the anode sur-face. In this contribution we present results of measurement of emission spectral lines of neutral copper along the jet. We are able to monitor presence of copper vapors in the jet and in addition we use copper lines to obtain excitation temperature. This temperature seems to represent kinetic temperature of turbu-lent downstream regions of the jet with good accuracy.

Keywords: DC arc, plasma jet, copper atoms, excitation temperature

* * *

Spectroscopic Study of Arc Temperature Profiles of a Switching-off Process in a Model Chamber

Methling R.¹, Franke St.¹, Uhrlandt D.¹, Gorchakov S.¹, Reichert F.², Petchanka A.²

¹ Leibniz Institute for Plasma Science and Technology (INP Greifswald), Felix-Hausdorff-Str. 2, 17489 Greifswald, Germany
² Siemens AG, EM HP CB R&D EN, Nonnendammallee 104, 13629 Berlin, Germany

A model chamber was applied to emulate a switching-off process which is very similar to those in real high-voltage circuit-breakers. The arc between moved W-Cu electrodes through a PTFE nozzle in SF6 was considered. Transparent windows in the chamber wall and a slit in the nozzle enabled an optical in-vestigation of the arc cross section several milliseconds before current zero. The side-on radiance of fluo-rine atom lines has been measured. Considering rotational symmetry of the arc the corresponding radial emission coefficients have been determined. Radial temperature profiles have been obtained with uncer-tainties below 10% considering change of window transmission and optical depth of the line radiation. The experimentally determined temperature profiles are used to validate a CFD simulation of the switch-ing-off process in the model chamber.

Keywords: circuit-breaker, arc temperature, spectroscopy

* * *

Spectroscopic Measurements of Arc Temperatures in a Model HV Circuit Breaker

Methling R.¹, Franke St.¹, Uhrlandt D.¹, Gortschakow S.¹, Panousis E.²

¹ Leibniz Institute for Plasma Science and Technology (INP Greifswald), Felix-Hausdorff-Str. 2, 17489 Greifswald, Germany
² ABB Corporate Research, ABB Switzerland, Segelhofstrasse 1K, 5405 Baden-Dättwil, Switzerland

Optical emission spectroscopy was applied to determine radial plasma temperature profiles over the arc cross section of an axially blown arc. Two gases are investigated - technical air and CO2. The diagnostics is based on optical emission spectroscopy in appropriate wavelength ranges containing atomic and ionic lines of oxygen as well as nitrogen and carbon, respectively. Radial temperature profiles are obtained from emission coefficients including pressure measurements and calculated plasma compositions.

Keywords: optical emission spectroscopy, arc, circuit breaker

* * *

Plasma-Catalytic Reforming of Raw Material for Biodiesel Production

Nedybaliuk O.¹, Fedirchyk I.¹, Chernyak V.¹, Bortyshevskyy V.², Iukhymenko V.¹, Korzh R.², Demchina V.³, Dragnev S.⁴

¹ Taras Shevchenko National University of Kyiv, 64/13, Volodymyrska Street, City of Kyiv, 01601, Ukraine
² Institute of Bioorganic Chemistry and Petrochemistry of NASU, 50, Kharkivske Shosse, City of Kyiv, Ukraine
³ Gas Institute of NASU, 39 Degtyarivska Street, City of Kyiv, 03113, Ukraine
⁴ National University of Bioresources and Environmental Sciences of Ukraine, 15, Heroyiv Oborony Street, City of Kyiv, 03041, Ukraine

Plasma-catalytic reforming of liquid hydrocarbons is considered in this paper. Rotating gliding discharge was used as the generator of non-equilibrium plasma. Vegetable oil (raw materials for the production of bio-diesel) and ethanol were used as model hydrocarbons. Efficiencies and transformation coefficients for the processes of vegetable oil and ethanol reforming are calculated.

Keywords: plasma-catalytic reforming, rotating gliding discharge, synthesis gas, ethanol, vegetable oil

* * *

Design and Test of a Technology Demonstrator for a CO₂ Filled Circuit Breaker with Two Heating Volumes

Nikolic P. G., Forschelen M., Wetzeler S., Schnettler A.

Institute for High Voltage Technology, RWTH Aachen University, Schinkelstrasse 2, 52056 Aachen, Germany

The revision of the European regulation on fluorinated greenhouse gases revived the search for possible SF6 (sulphur hexafluoride) substitutes as arc quenching and insulating medium in high voltage gas circuit breakers and gas insulated switchgear. Nevertheless an objective evaluation of possible SF6 alternatives requires a deep knowledge and understanding of the physical and technical limits of these technologies. In previous investigations the thermal interruption capability of the possible substitute CO₂ (carbon dioxide) was investigated by means of circuit breaker models. By comparison with computational fluid dynamics simulations design criteria for circuit breakers filled with CO₂ are determined in this research work. Based on these a technology demonstrator of a circuit breaker is constructed for a short circuit current of I_sc = 25 kA_rms with a switching chamber adapted to the physical and thermodynamic properties of CO₂. Therefore a nozzle system with two heating channels supplied from two heating volumes is used. The thermal interruption capability of this CO₂ circuit breaker is experimentally investigated in a synthetic test circuit and the number of succeeding successful current interruptions is determined. Finally an outlook on the dielectric strength of the demonstrator is given based on simulative investigations and modelling.

Keywords: circuit breaker, SF6 substitution, CO₂, technology demonstrator

* * *

Internal Arc CFD Simulation of Long Single Phase HV-GIS

Ostrowski J., Galletti B., Hencken K., Lehmann J., Seeger M.

ABB Corporate Research, Segelhofstrasse 1k, CH-5405 Baden, Switzerland

A novel one-dimensional CFD-tool for the simulation of the pressure build up during internal arc faults in long single phase High Voltage SF6 Gas Insulated Switchgear (HV-GIS) is presented in this paper. We do not use the common empirical thermal transfer coefficient (Kp factor) in our tool. Instead a more physically motivated approach has been developed and is introduced here. The approach includes important cooling mechanisms that prevent excess gas/plasma-temperatures and subsequent numerical instabilities. In order to understand if the approach is valid, we prescribe the arc-energy from a benchmark experiment. Then we compare the simulated pressure build-up curve with the measured pressure build-up.

Keywords: internal arc, simulation, CFD, high voltage, gas insulated switchgear, SF6-Al

* * *

Application of Laser Arc Imaging Technology to Observe Arc Behavior and Contact Motion

Qu J.¹, Yuan S.¹, Wang Q.², Li X.¹

¹ State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an Jiaotong University No.28, Xianning West Road, Xi'an, Shaanxi, 710049, China
² School of Sciences, Xi’an University of Technology, Xi’an, Shaanxi, China

The arc behavior and the contact motion in a miniature circuit breaker with transparent housings are ob-served by a laser arc imaging system. In the system, an expanded laser beam is used to illuminate the arc quenching chamber, and the chamber with burning arc is recorded by a high speed camera. In front of the camera, an optical band-pass filter is mounted. The recorded frames provide crucial information of the arc behavior and the contact motion. Some quantitative results including displacements and velocity of the movable contacts are collected from the frames.

Keywords: laser imaging technology, arc behavior, contact motion, low voltage circuit breaker

* * *

Cathode Arc Root Movement: Models Comparison

Quemeneur J.¹, Freton P.¹, Masquere M.¹, Gonzalez J. J.¹, Joyeux P.²

¹ Université de Toulouse UPS; LAPLACE (LAboratoire PLAsma et Conversion de l’Energie UMR 5213); 118 route de Narbonne, 31062 Toulouse cedex 9, France
² Hager Electro SAS, Boulevard d’Europe, BP3, 677215 Obernai Cedex, France

Efficiency of the Low-Voltage Circuit Breaker (LVCB) goes through the fast movement of the arc from the contact to the splitter plates. Consequently, any complete fluid model of this process must allow the displacement of the electrical arc roots. In this paper, we will investigate the arc movement both experi-mentally and theoretically.

Keywords: thermal plasma modelling, low-voltage circuit breaker, LVCB, arc movement

* * *

Switching Performance of Weakly Cooled Arcs

Ranjan N., Carstensen J., Stoller P., Schwinne M., Over D., Votteler T.

ABB Switzerland Ltd, Corporate Research, Segelhofstrasse 1, 5405 Baden-Dättwil, Switzerland

Understanding the response of a low current and weakly cooled arc in subsonic axial flows is important to effectively control the switching in medium voltage switchgear. We have looked into the effect of blowing overpressure on the switching behaviour of an arc in air for conditions relevant to load break switches. The transient recovery voltage was chosen according to the active load break test duty.

Keywords: low current arcs, subsonic flows, low blowing, load break switches

* * *

Studies on the Thermal Re-ignition in SF6 High-Voltage Circuit-Breakers by means of Coupled Simulation

Reichert F.¹, Petchanka A.¹, Freton P.², Gonzalez J. J.²

¹ Siemens AG, EM HP CB R&D E, Nonnendammallee 104, 13629 Berlin, Germany
² Université de Toulouse, LAPLACE, 118 route de Narbonne, CNRS-UPS-INP, F-31062 Toulouse, France

The paper presents a modelling approach to study the switching capacity of SF6 high-voltage circuit breakers with respect to the thermal re-ignition. This approach is based on the coupling of a model for the thermal re-ignition and a model describing the transient response of an external circuit. It is pointed out that the switching capacity can be evaluated taking into account the simulated trends for the transient recovery voltage similar to the approach in real tests. The different behaviour of the regarded SF6 self-blast circuit-breaker at different arcing times is highlighted using simulation results for pressure, temperature and electrical conductivity.

Keywords: high-voltage circuit-breaker, CFD, switching arc, thermal re-ignition

* * *

Interaction of Hydrogen Microwave-Induced Plasma with Titania Nanotube Arrays (TONT)

Savitsky A., Pankov V.

Belarusian State University, 4 Nezavisimosti av., 220050 Minsk, Republic of Belarus

Experimental research of hydrogen plasma interaction with a surface of TONT is presented. Atomic hydrogen absorption results in formation of hydrides, while molecular hydrogen can be absorbed just physically. It is shown, that energy of hydrogen plasma is a major factor that defines the interaction mechanism and kinetics of the process.

Keywords: plasma, hydrogen, sorption, desorption, electrochemistry

* * *

Preliminary Spectroscopic Investigation of HVCB Contacts Erosion

Wang Z. X.^1,2, Spencer J. W.², Yan J. D.², Jones G. R.², Humphries J. E.², Rong M. Z.¹, Wang X. H.¹

¹ Xi’an Jiaotong University, 28 Xianning West Rd., Xi’an, 710049, China
² University of Liverpool, Brownlow Hill, Liverpool, L69 3GJ, UK

Spectral emissions from arcs in air between electrodes used in high-voltage circuit breakers (HVCBs) have been investigated at AC currents up to 32kA peak. Time-resolved average temperature and copper atoms concentration have been derived from the arc spectra. The copper vapor mass deduced from these measurements was used to estimate the electrode erosion rate which was compared with directly meas-ured material loss. High speed photographs of the arc were taken to provide further electrode erosion in-formation. The results indicate the possibility of using the approach for online monitoring of in-service HCVBs.

Keywords: spectroscopic, condition monitoring, electrode erosion, HVCB

* * *

Net Emission Coefficient of Nitrogen-PTFE Gas Mixture in Thermal and Chemical Equilibrium

Yang F.¹, Yuan D.², Yan J. D.¹

¹ Department of Electrical Engineering and Electronics, University of Liverpool, Liverpool, L69 3GJ, United Kingdom
² Pinggao Group Co Ltd, Nanhuandong Road, Pingdingshan, Henan Province, PR China, 467001

The net emission coefficient (NEC) of pure nitrogen gas and its mixture with PTFE vapour in plasma state is calculated over the pressure range of 1 to 100 bar and temperature range of 300 to 35,000 K. 26 species are included in the NEC calculation for N₂-PTFE mixture. Results are compared with existing data to assess the applicability of the method.

Keywords: NEC, nitrogen, PTFE, radiation

* * *

Experimental Study on Rotary Arcs in CO₂ Model Gas Circuit Breaker

Yoshino T.¹, Kawano H.¹, Mori T.¹, Miyazaki K.¹, Fujino T.²

¹ TOSHIBA Co., 2-1 Ukishima-cho Kawasaki 210-0862, Japan
² University of Tsukuba, 1-1-1 Tennnodai Tsukuba 305-8577, Japan

The present study has examined the influence of rotary arcs with a permanent magnet in CO₂ gas circuit breaker under conditions of low and high current interruption. The rotary arc extremely increases extinction peak and decreases arc conductance of 200ns before current zero in the case of low current condition, because the rotary arc generates the rotation gas velocity and enhances turbulent energy transport, when there is no pressure rise of thermal puffer in the case of low current.

Keywords: rotary arc, CO₂, GCB

* * *

Fast tracking abstracts for volume 2, number 2.

Volume 2, Number 3

Modelling Radiative Properties of SF₆ Arc Plasma

Bartlova M., Bogatyreva N., Aubrecht V.

Faculty of Electrical Engineering and Communication, Brno University of Technology, Technicka 10, 616 00 Brno, Czech Republic

The objective of this work is to compare the accuracy of several approximate radiative properties models for the prediction of radiative transfer in SF₆ arc plasma at the temperatures in the range of 300–25000 K and pressure of 1 MPa. Calculated absorption coefficients are used to generate the parameters of different approximate models. In order to compare the accuracy of various approximate models, the radiative transfer inside the cylindrically symmetrical SF₆ plasma with prescribed temperature profile was calculated using the P1-approximation.

Keywords: plasma radiation, SF₆ arc plasma, radiative property modelling

* * *

Diffuse Coplanar Surface Barrier Discharge: Influence of Gas Humidity on Plasma Parameters

Cech J., Stahel P., Dvorakova H., Cernak M.

CEPLANT - R&D Center for Low-Cost Plasma and Nanotechnology Surface Modification, Masaryk University, Kotlářská 2, 611 37 Brno, Czech Republic

It was found that the working gas humidity influences substantially the parameters of diffuse coplanar surface barrier discharge. The absolute humidity of air or N₂ has a strong influence on the discharge pattern and its macroscopic homogeneity. The amount of H₂O in working gas influences also generated radicals and the plasma chemistry. We suggest that the humidity of working gas should be a controlled parameter of in-line atmospheric pressure plasma treatment under real industrial conditions.

Keywords: DCSBD, barrier discharge, atmospheric pressure, humidity, pattern, OES

* * *

The Problem of Chemically Active Plasma Nonequilibrium. Review

Chernyak V., Nedybaliuk O., Martysh E., Solomenko O., Fedirchik I., Iukhymenko V., Prysiazhnevych I., Veremii Iu.

Taras Shevchenko National University of Kyiv, Faculty of Radio Рhysics, Electronics and Computer Systems, Kyiv, Ukraine A.J. Drexel Plasma Institute Drexel University 3141 Chestnut Street Philadelphia, PA 19104, USA

Data on the negative impact of exothermic chemical reactions on the level of non-isothermal plasma are presented. Therefore the transition from the plasma activation of the fuel mixture (fuel/oxidant) to only plasma activation of oxidant leads to a substantial increase in the coefficient of electric energy transformation into chemical energy (α) of produced synthesis gas in hybrid plasma-catalysis system of hydrocarbons reforming (α ≤ 400).

Keywords: non-isothermal plasma, plasma-catalysis system, hydrocarbons reforming

* * *

Microdischarge in the Vortex Gas Flow

Chernyak V., Solomenko Ok., Solomenko Ol., Lendiel V., Kalustova D., Prysiazhnevych I.

Taras Shevchenko National University of Kyiv, Glushkova av. 4g, Kyiv, Ukraine

Current-voltage characteristics of the DC microdischarge were investigated in the work. The plasma jet parameters ware evaluated by emission spectroscopy method. The component composition and the temperatures of excited electronic, vibrational and rotational levels of plasma component of microplasma were determined by using emission spectra. It was found that nitrogen was the main component of microdischarge plasma. Also NO and OH molecular bands were presented in the spectrum.

Keywords: atmospheric pressure plasma, microdischarge, plasma jet

* * *

Change of the Thermal Profile in the Modern MCCB by the Different Electrical Contact Resistance

Dostal L., Dohnal P., Valenta J.

Centre for Research and Utilization of Renewable Energy (CVVOZE), Technicka 10, 616 00 Brno, Czech Republic

The paper deals with the change of temperature rise of the MCCB at the steady state.
The critical parts under the study are main contacts and contact lever. The movable contact in focus is modern, rotoactive system which moves contact along a circular path and his material is harder than the fixed one. It causes sequential sag of the movable contact followed by a deformation of the fixed one. Consequently, the contact area between the pair of contacts is increasing, but the contact material is losing during the arc quenching. Rests and dirt layers appear on the contact surfaces and causes increase electric and thermal resistances between contacts. Temperature rise of the device with additive layers after arcing increases against new one at the steady state. The profiles of the temperature rises are computed using finite volume method (FVM). The first part of the paper focuses on the calculation of the thermal losses of the electrical current path at rated current with the different electrical contact resistance.
The last part of the paper describes laboratory measurements performed for numerical calculations verification. Results of the laboratory measurements proved the accuracy of the finite volume method model.

Keywords: MCCB, temperature profile, thermal losses, Computational Flow Simulation

* * *

Change of the Thermal Profile in the Modern MCCB by the Different Electrical Contact Resistance

Dostal L., Dohnal P., Valenta J.

Centre for Research and Utilization of Renewable Energy (CVVOZE), Technicka 10, 616 00 Brno, Czech Republic

Keywords: MCCB, temperature profile, thermal losses, Computational Flow Simulation

* * *

Preliminary Study of Mixing of Plasma Species in a Hybrid-Stabilized Argon-Water Electric Arc

Jenista J.¹, Takana H.², Uehara S.², Nishiyama H.², Murphy A. B.³, Bartlova M.⁴, Aubrecht V.⁴

¹ Institute of Plasma Physics AS CR, v.v.i., Za Slovankou 3, 182 00 Praha 8, Czech Republic
² Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi, 980-8577, Japan ³ CSIRO Materials Science and Engineering, PO Box 218, Lindfield NSW 2070, Australia
⁴ Brno University of Technology, Technická 8, 616 00 Brno, Czech Republic

This paper focuses on numerical simulation of mixing of plasma chemical species in the discharge and near-outlet regions of the worldwide unique type of thermal plasma generator with hybrid stabilization of electric arc by axial argon flow and tangential water vortex. Results of simulation for 300-500 A indicate inhomogeneous mixing of argon and oxygen-hydrogen species for all currents. The argon diffusion mass flux is driven mainly by the concentration and temperature space gradients.

Keywords: arc discharge, combined diffusion coefficients, inhomogeneous mixing, mass fraction

* * *

Nisin Immobilization on Plasma Treated Polyvinyl Alcohol Films

Kolarova Raskova Z.¹, Stahel P.², Hrabalikova M.¹, Sedlarik V.¹

¹ Centre of Polymer Systems, Tomas Bata University in Zlin, tr. Tomase Bati 5678, 76001 Zlín, Czech Republic
² Department of Physical Electronics, Faculty of Science, Masaryk University, Kotlarska 267/2, Brno Czech Republic

Nisin protein attachment on chemically crosslinked polyvinyl alcohol surface activated in atmospheric Dielectric Coplanar Surface Barrier Discharge was carried out in this work. Plasma activated PVA surfaces show improved level of nisin attachment in comparison with untreated films. In addition, the extent of the nisin surface immobilization and its release strongly depends on crosslinking degree of PVA substrate.

Keywords: nisin, polyvinyl alcohol, surface modification, antimicrobial activity, crosslinking

* * *

Why the Arc, and its Interactions with the Electrodes, Are Important in Predictive Modelling of Arc Welding

Murphy A. B.

CSIRO Manufacturing, PO Box 218, Lindfield NSW 2070, Australia

The importance of two-way interactions between the arc and electrodes in welding is demonstrated by three examples: the influence of weld pool surface deformation on heat transfer, the momentum and energy transferred by droplets, and the effects of metal vapour on the arc and weld pool. It is concluded that a predictive model of arc welding requires the arc to be included in the computational domain. This will also facilitate calculation of properties such as microstructure and residual stress.

Keywords: arc welding, computational modelling, metal vapour, droplets, thermal plasma

* * *

Development of Long Flashover and Multi-Chamber Arresters and Insulator-Arresters for Lightning Protection of Overhead Distribution and Transmission Lines

Podporkin G. V.

Streamer Electric Company, 195220 Saint-Petersburg, Russia

Long Flashover Arresters (LFAs) were suggested and developed for lightning protection of Medium voltage lines 3-35 kV against induced overvoltages and direct lightning strokes. Main feature of LFAs is increased length of lightning flashover path. The LFA's length may be several times greater than that of an insulator (string, etc.). Due to a special inner structure the LFA impulse flashover voltage is lower than that of the insulator and when subjected to lightning overvoltage the LFA flashovers before the insulator. Increased length of flashover insures quenching of power arc follow when current crosses zero. This phenomena can be called “zero quenching”. Main advantage of LFAs is that current and energy pass outside the arresters. Reported also are results of research and development of multi-chamber arresters (MCA) and insulators (MCIA) that combine characteristics of insulators and arresters. The base of multi-chamber arresters (MCA), including MCIA, is the multi – chamber system MCS. MCS of first generation comprises a large number of electrodes mounted in a silicon rubber length. Holes drilled between the electrodes and going through the length act as miniature gas discharge chambers. MCS of this type insures power arc quenching when follow current crosses zero (“zero quenching”). MCS of second generation has more complicated chamber design but it quenches impulse arcs without a follow power arc (“impulse quenching”). The devices permit protection of overhead power lines rated at 10 to 220 kV and above against induced overvoltages and direct lightning strokes without using a shield wire.

Keywords: lightning protection, overhead lines, flashover, arc, quenching, multi chamber arresters

* * *

Pulsed Plasma Spraying of Liquid Feedstock for Coating Elaboration

Rat V., Mavier F., Bienia M., Lejeune M, Coudert J.F.

CNRS, University of Limoges, ENSCI, SPCTS UMR7315, European Ceramic Centre 12 rue Atlantis 87068 Limoges cedex, France

Self-sustained nitrogen pulsed plasma is studied by electrical and optical diagnostics. It is used to deposit coatings when the injection of suspensions of nanoparticles is synchronized with the arc voltage.

Keywords: pulsed plasma torch, plasma spraying, diagnostics, model

* * *

Arc Modeling Challenges

Rümpler Ch.¹, Narayanan V.R.T.²

¹ Eaton, 1000 Cherrington Pkwy, Moon Township, PA 15108, USA
² Eaton, Bořivojova 2380, 252 63 Roztoky, Czech Republic

Modeling of arcing phenomena has evolved towards becoming a state-of-the-art tool, supporting the design process of power distribution equipment in low-, medium-, and high-voltage applications. Modeling provides a better understanding of the physical processes within the devices which is needed in order to enhance product performance and mitigate risks in the development cycle. In this contribution, modeling challenges related to some of these applications are discussed: a) the calculation of thermodynamic and transport properties, b) the modeling approach for contact arm motion during arc interruption in lowvoltage molded case circuit breakers (MCCB’s), c) the model approach for arc flash events in mediumvoltage (MV) switchgear.

Keywords: arc simulation, plasma transport properties, circuit breaker, switchgear

* * *

Investigation of Plasma Properties in a Narrow Gap for Short Time Current

Runge T., Kopp T., Kurrat M.

Technische Universität Braunschweig, Institute for High Voltage Technology and Electrical Power Systems, Schleinitzstraße 23, 38106 Braunschweig, Germany

In the current study an experimental model was established, in which the plasma is quenched in a defined narrow gap and tested with an 8/20 µs impulse current with an amplitude of 23 kA. The experimental model is equipped with an outlet duct of different cross sectional areas. The measured data such as arc voltage and current are used in order to estimate the plasma properties electrical conductivity and pressure.

Keywords: surge current, plasma properties, lightning protection, spark gap

* * *

Future Perspectives on High Voltage Circuit Breaker Research

Seeger M.

ABB Switzerland Ltd, Corporate Research, Segelhofstrasse 1, CH-5405 Baden-Dättwil, Switzerland

The research on high voltage circuit breakers using SF₆ is addressed. An overview of current state of research in this field will be given and possible future research directions will be discussed on examples. Such directions are, for example, the radiative energy transport, the understanding and description of ablation processes at the nozzle and contact surfaces, the influence of ablated vapors on pressure build up and interruption capability, the electric breakdown processes, departures from equilibrium, turbulence and the importance of magnetic fields and 3D modelling.

Keywords: arc, circuit breaker, high voltage, SF₆

* * *

Extended Methods of Emission Spectroscopy for the Analysis of Arc Dynamics and Arc Interaction with Walls

Uhrlandt D., Methling R., Franke St., Gorchakov S., Baeva M., Khakpour A., Brüser V.

Leibniz Institute for Plasma Science and Technology (INP Greifswald), Felix-Hausdorff-Str. 2, 17489 Greifswald, Germany

Recently, a number of improved methods of optical emission spectroscopy have been proposed for the study of high-current arcs with special emphasis on the treatment of optical thick arc radiation and analysis of the arc dynamics. The paper gives a short review on these methods focusing on the determination of plasma properties by means of comparison of measured and simulated emission spectra and the use of high-speed video spectroscopy. The application of these methods is demonstrated for a specific example; the study of the interaction of arcs with side walls and the impact of ceramic coatings on the wall’s protection. For that purpose, a free burning arc experiment with CuW electrodes is used. The strong electrode erosion causes the arc operation in copper vapour with high stability and reproducibility. The arc temperature profile is obtained from measurements of copper line radiation complemented with radiation transport simulations. The impact of the arc radiation on the evaporation of different ceramic coatings of side walls is studied by video spectroscopy. The resulting impact on the heat load of the walls is derived from thermographic measurements.

Keywords: optical emission spectroscopy, plasma temperature, arc wall interaction

* * *

Diagnostics of Extinguishing Process in Low Voltage Devices by Pressure Field Measurement

Valenta J., Dohnal P., Dostal L.

Centre for Research and Utilization of Renewable Energy, FEEC, Brno University of Technology, Technicka 10, Brno, Czech Republic

The article deals with the diagnostics of extinguishing process in low voltage devices by the means of pressure measurement in several points. The first part explains the technique of pressure measurement in switching devices and focuses on proper sensor properties and the problems of natural frequencies of the whole setup. The second part contains an example of pressure measurement analysis of the real device under real conditions, i.e. with the values of short-circuit currents in the range of tens of kA of prospective current with full voltage performed in the Laboratory of switching devices, Brno University of Technology. The last part compares the diagnostics method based on pressure measurement with other diagnostics techniques suitable for arc burning study under real conditions.

Keywords: pressure measurement, extinguishing process

* * *

Modelling of Turbulent SF6 Switching Arcs

Zhang Q.¹, Yan J. D.¹, Yan G.²

¹ Department of Electrical Engineering and Electronics, the University of Liverpool, Brownlow Hill, Liverpool, L69 3GJ, UK
² Henan Pinggao Group Co., Ltd. Nanhuandong Road, Pingdingshan City, 467001, China

The present work aims at a comparative study of the performance of relevant turbulence models in predicting the behaviour of SF_{6_{switching arcs during the current zero period. Turbulence models studied include the Prandtl mixing length model, the standard k-ε model and its two variants, i.e. the Chen-Kim model and the RNG model. In order to demonstrate the effects of turbulence, a laminar flow case is also modelled. Based on the computational results, a detailed analysis of the physical mechanisms encompassed in each flow model is given to show the adequacy of each model in describing the rapidly varying arcing process during the current zero period. The computed values of the critical rate of rise of recovery voltage (RRRV) are subject to verification by experimental results covering a wide range of discharge conditions. The relative merits of the flow models are discussed.}}

Keywords: SF₆ switching arcs, turbulence models, current zero period

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Fast tracking abstracts for volume 2, number 3.