## Plasma Physics and Technology Journal

Volume 4 (2017)

### Number 3

**Advanced Nonequilibrium Modelling of DC Tungsten-Inert Gas Arcs**

Baeva M., Uhrlandt D.

*Leibniz Institute for Plasma Science and Technology,
Felix-Hausdorff-Strasse 2, 17489 Greifswald, Germany
*

The paper is concerned with the state-of-the-art nonequilibrium modelling of a DC tungsten-inert gas arc plasma. The advanced description involves the two-way interaction between the plasma and the electrodes. Results in atmospheric pressure argon demonstrating important features of the arc plasma are presented and discussed. First results in the presence of metal vapour released from the molten anode are presented. Outlook for further developments in nonequilibrium arc modelling are discussed.

**Keywords: **
nonequilibrium, arc plasma, magnetohydrodynamic model, diffusion, plasma-electrode interaction.

* * *

**Modelling and Simulation of SF ^{6} High-Voltage Circuit-Breakers - an Overview on Basics and Application of CFD Arc Simulation Tools**

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

^{1}*Siemens AG, Nonnendammallee 104, 13629 Berlin, Germany
*

^{2}*University Paul Sabatier, LAPLACE, 118 route de Narbonne, CNRS-UPS, 31062 Toulouse, France*

The paper gives an overview on the basics of CFD arc simulation tools with respect to the
simulation of the fluid mechanical processes in the interrupter unit of SF^{6} high-voltage
circuit-breakers at no-load and short-circuit switching-off processes. On the example of SF^{6}
self-blast circuit-breakers the complete process from the analysis of the switching-off process
to the creation of a modular simulation model consisting of several sub models is illustrated.
Details to the modelling in the particular sub modules and to the implementation are given. The
capability of a CFD arc simulation tool based on the program package ANSYS/FLUENT is demonstrated
on the basis of selected simulation results. Furthermore case examples for the application of the
presented CFD arc simulation tool in the development process of high-voltage circuit-breakers are
given.

**Keywords: **
high-voltage circuit-breaker, CFD arc simulation tool, modelling, application.

* * *

**Non-equilibrium Studies in Switching Arc Plasmas in Japan**

Tanaka Y.^{1}, Tomita K.^{2}, Inada Y.^{3}, Kumada A.^{4},
Hidaka K.^{4}, Fujino T.^{7},Suzuki K.^{5}, Shinkai T.^{6}

^{1}*Kanazawa University, Kakuma, Kanazawa, Ishikawa 920-1192, Japan*

^{2}*Kushu University, Kasuga, Fukuoka 816-8580, Japan*

^{3}*Saitama University, 542 Shimo-Okubo, Sakura, Saitama 338-8570 Japan*

^{4}*The University of Tokyo,7-3-1 Hongo, Bunkyo, Tokyo 113-8654, Japan*

^{5}*University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577, Japan*

^{6}*Tokyo Denki University, 5 Senju Aasahi, Adachi, Tokyo 120-8551, Japan*

^{7}*Tokyo University of Technology, 1404-1 Katakura, Hachioji, Tokyo 192-0982, Japan*

This paper briefly introduce research work examples of non-equilibrium studies in switching arcs. In understanding arc behavior, one often assumes local thermodynamic equilibrium (LTE) condition in the arc plasma. However, actual arc plasmas are not completely and not always in LTE state because of strong temperature change temporally and spatially, and high electric field application etc. Recently, we have a collaboration work in numerical simulations and experimental approaches for decaying arcs without LTE assumption. First, our numerical model is presented for decaying arcs without chemical equilibrium assumption. Secondly, two experimental methods are introduced for measuring electron density in decaying arcs without LTE assumption: Laser Thomson Scattering method and the Schack-Hartmann method. Finally, comparison results is shown between the LTE simulation, the chemically non-equilibrium simulation, and the above experimental measurements.

**Keywords: **
local thermodynamic equilibrium, chemically non-equilibrium, thermally non-equilibrium, electron density measurement.

* * *

**Mechanisms Responsible for Arc Cooling in Different Gases in Turbulent Nozzle Flow**

Guo Y.^{1}, Zhang H.^{1}, Yao Y.^{1}, Zhang Q.^{2}, Yan J. D.^{2}

^{1}*Pinggao Group Co. Ltd., Pingdingshan City, Henan, China, 467001
*

^{2}*Department of Electrical Engineering and Electronics, the University of Liverpool, Liverpool L69 3GJ, the U.K.
*

A high voltage gas blast circuit breaker relies on the high speed gas flow in a nozzle to
remove the energy due to Ohmic heating at high current and to provide strong arc
cooling during the current zero period to interrupt a fault current. The physical
mechanisms that are responsible for the hugely different arc cooling capabilities of two gases
(SF_{6} and air) are studied in the present work and important gas material properties
controlling the cooling strength identified.

**Keywords: **
SF_{6} replacement, SF_{6} alternative gases, switching arc.

* * *

**Synthetic Testing of Load Current Interruption in Medium Voltage Load Break Switches**

Bendig M.^{1}, Ksoll M.^{1}, Kalter A.^{2}, Schaak M.^{2},
Ermeler K.^{3}, Schnettler A.^{1}

^{1}*Institute for High Voltage Technology, RWTH Aachen University, Schinkelstr. 2, 52056 Aachen, Germany
*

^{2}*Siemens AG, Energy Management Division, Carl-Benz-Str. 22, 60386 Frankfurt am Main, Germany
*

^{3}*Siemens AG, Energy Management Division, Nonnendammallee 104, 13629 Berlin, Germany*

To conduct the mainly active load current test duty according to IEC 62271-103, a directly powered test circuit and therefore a medium voltage connection or a power generator is needed. A newly developed synthetic test circuit allows to replicate the current as well as the full transient recovery voltage (TRV) and the power frequent recovery voltage (RV) of the direct test circuit up to its crest value. It is dimensioned for voltage classes up to 52 kV and can be adapted to test currents between 630 A and 1250 A. The test circuit allows a detailed investigation of load break switches without costly high power sources and loads. Many parameters, like current and voltage steepness at current zero, as well as different parameters defining the TRV steepness can be varied individually.

**Keywords: **
load switching, synthetic testing, circuit simulation, load break switch.

* * *

**Development of an Experimental Approach for Determining the Arc Quenching Capability of Different Gases**

Ksoll M.^{1}, Bendig M.^{1}, Nikolic P. G.^{2}, Schnettler A.^{1}

^{1}*Institute for High Voltage Technology, RWTH Aachen University, Schinkelstr. 2, 52056 Aachen, Germany*

^{2}*Siemens AG, Corporate Technology, G\"unther-Scharowsky-Str. 1, 91058 Erlangen, Germany*

After being in the focus of sciences' and industry's research and development activities for many
years, the investigation of possible SF^{6} (sulfur hexafluoride) gas-alternatives
has been even more intensified after the revision of the European regulation on fluorinated gases
in 2014. This contribution focuses on the scientific assessment of the technical performance
of several SF^{6} gas-alternatives - gases and gas mixtures - currently under discussion.
Therefore, a reference experimental setup, that allows the determination of the arc quenching
capability of different gases as well as the axial resistance distribution of the switching arc
around current zero crossing, is developed. Additionally, first experimental results for the thermal
interruption capability and the arc resistance distribution of SF^{6} and possible
SF^{6} gas-alternatives are shown.

**Keywords: **
arc quenching capability, SF^{6} gas-alternatives, arc resistance distribution.

* * *

**Emission Spectroscopy During High-Current Anode Modes in Vacuum Arc**

Khakpour A., Methling R., Franke St., Gortschakow S., Uhrlandt D.

*Leibniz-Institut for Plasma Science and Technology, Felix-Hausdorff-Str. 2, 17489 Greifswald, Germany
*

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.

**Keywords: **
vacuum arc, high-current anode phenomena, emission spectroscopy.

* * *

**Radiation Transfer in Arc Plasmas**

Bogatyreva N.^{1}, Bartlova M.^{1}, Aubrecht V.^{2}, Kloc P.^{2}

^{1}*Department of Physics, Faculty of Electrical Engineering and Communication, Brno University of Technology, Technicka 3058/10, 616 00 Brno, Czech Republic
*

^{2}*Department of Power Electrical and Electronic Engineering, Faculty of Electrical Engineering and Communication, Brno University of Technology, Technicka 3058/12, 616 00 Brno, Czech Republic
*

In this paper, attention has been given to the absorption properties of the arc plasma at the different pressure conditions. Calculations of the absorption coefficients for a thermal plasma have been performed as a function of the temperature and the frequency. Methods for prediction of the average absorption coefficients were described and compared in detail.

**Keywords: **
air plasma, radiation transfer, absorption coefficient.

* * *

**Diagnostics of Various Phenomena in LV Devices Under Real Switching Conditions**

Valenta J., Samohejl M., Fendrych M., Kloc P., Dostal L.

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

The article deals with issues to be tackled when performing experiments with low voltage devices under real switching conditions and subsequently discusses various phenomena in an experimental device. The first part describes optimum setting of diagnostic equipment - mainly for optical diagnostic methods. The second part describes some phenomena encountered during switching process under real switching conditions -- arc roots movement (cathode and anode spots). These phenomena are not only important for experimental study itself but also form necessary input data for numerical models and their validation.

**Keywords: **
electric arc, optical diagnostics, high speed video, arc root movement.

* * *

**Modelling of Radiative Transfer in Air Arc Plasma**

Bartlova M.^{1,2}, Kloc P.^{1}, Bogatyreva N.^{2}, Aubrecht V.^{1}, Pokorny J.^{2}

^{1}*Technische Universität Braunschweig, Institute for High Voltage Technology and Electrical Power Systems,
38106 Braunschweig, Germany
*

^{2}*Department of Physics, FEEC, Brno University of Technology, Technicka 10, 616 00 Brno, Czech Republic
*

The objective of this work is to compare the accuracy of several approximate models of radiative properties for the prediction of radiative transfer in air arc plasma at the temperatures in the range of 300 - 25 000 K and the pressure of 0.1 MPa. Calculated absorption coefficients are used to generate the parameters of different models. The radiative transfer inside the cylindrically symmetrical air plasma with prescribed temperature profile was studied. The equation of radiative transfer was solved using the P$_1$ and SP$_3$ approximations, calculated radiative source term in the energy equation (net emission) was compared with results obtained by spectral integration.

**Keywords: **
radiative transfer, P_{1} approximation, SP_{3} approximation, mean absorption coefficients.

* * *

**Experimental Temperature Measurements in Miniature Circuit Breaker**

Simek D., Pecek D.

*Faculty of Electrical Engineering and Communication, Brno University of Technology, Technicka 3058/10, 616 00 Brno, Czech Republic
*

Low voltage switching apparatuses efficiency depends on the speed of movement of the switching arc from the contacts to the quenching chamber. The paper is focused on investigation of this movement of an arc. Measurement of radiation spectra of the electric arc burning inside miniature circuit breaker and moving to quenching chamber are presented. Measured radiation spectra contain suitable atomic spectra lines for calculation purposes. The problems connected with the measurements are discussed. The main part of the paper deals with a calculation of temperature of the investigated plasma of the arc. Atomic lines database of National Institute of Standards and Technology was used as a spectral data source for the calculations.

**Keywords: **
switching arc, miniature circuit breaker, atomic emission spectroscopy, temperature measurement.

* * *

**Objective Function for Numerical Mean Absorption Bands Optimization**

Kloc P., Aubrecht V., Bartlova M.

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

Mean absorption coefficients (MACs) offer great potential for fast numerical calculation of radiation heat transfer. They are based on replacing complex absorption coefficient spectrum by a handful of frequency bands with a single, temperature dependent value assigned to each band. Accuracy of radiation transfer calculation thus depends on the accurate interpretation of the mean value inside each frequency band as well as on the proper band distribution. Yet finding optimal band distribution is not an easy task often requiring numerical optimization process. This contribution focuses on the parameters of such optimization process, namely selection of an objective function and its effect on the optimal band distribution. It demonstrates, that improper objective functions can produce physically unreasonable artifacts in the calculation of radiation heat transfer. Optimal formulation of the objective function is proposed in this contribution.

**Keywords: **
mean absorption coefficients, numerical optimization, radiation transfer.

* * *

**A Review of Progress Towards Simulation of Arc Quenching in Lightning Protection Devices Based on Multi Chamber Systems**

Chusov A.^{1}, Rodikova E.^{1}, Murmann M.^{2}, Nordborg H.^{2},
Fuchs R.^{2}

^{1}*Streamer Electric, St Petersburg, 191024, Russia
*

^{2}*Institute for Energy Technology, HSR, Rapperswil, 8640, Switzerland
*

Two distinct modes of follow current suppression were observed in multi-chamber systems (MCS) under lightning overvoltage: Zero Quenching (ZQ) and Impulse Quenching (IQ). Sufficiently lower erosion of electrodes and evaporation of discharge chamber walls makes the IQ more preferable as a mechanism of arc quenching. Since experimental search for best MCS design is both difficult and expensive numerical modeling is considered as a prospective method for geometry optimization. Several steps were made towards development of efficient arc model. This article highlights most important results of arc quenching simulation and current status of arc model development.

**Keywords: **
lightning protection, multi-chamber system, arc discharge, plasma simulations, design optimization.

* * *

**Program Processing Database Data for Calculation of Spectral Lines Width and Shift in Plasma**

Pokorny J.

*Faculty of Electrical Engineering and Communication, BUT in Brno, Technicka 3058/10, 616 00 Brno, Czech Republic*

Electric and magnetic fields cause splitting of energy levels in~an~atom. Transition of electrons
among these levels could be seen as broadening and shift of spectral lines. We
recognize various types of effects, the most important is Stark effect. We developed a program
for calculations of temperature dependence linear coefficients of Stark broadening and
shift of spectral lines. Our results were calcutated for temperatures usual for SF^{6}
circuit breaker.

**Keywords: **
spectral line broadening, spectral line shift, Stark effect, Van der Waals effect.

* * *

**Modeling of the Interaction between the Switching Arc and Hydraulic Driving Mechanism in Gas-blast Circuit Breakers**

Zhang H.^{1}, Cao K.^{2}, Zhang Q.^{2}, Yan J. D.^{2}

^{1}*Pinggao Group Co. Ltd., Pingdingshan City, Henan, China, 467001*

^{2}*Department of Electrical Engineering, University of Liverpool, Brownlow Hill, Liverpool, UK*

The presence of an arc in a circuit breaker interrupter creates an opposing force to the driving mechanism by changing of the pressure field. This opposing force alters the dynamics of the driving mechanism, the travel characteristics of the moving contact and therefore the switching process. The severity of the influence depends on the structure of the interrupter, the travel profile and also the current waveform, especially the magnitude of the fault current. A 252 kV puffer circuit breaker was used in the present work to study the key factors that contribute to the uncertainty of the predicted contact travel based on coupled simulation.

**Keywords: **
coupled simulation, driving mechanism, switching arc.

* * *

### Number 2

**Optical Investigations on Plasma Temperature
Estimation in a Model Spark Gap for Surge Currents**

Rungea T.^{1}, Franke St.^{2}, Gortschakow S.^{2}, Kurrat M.^{1}

^{1}*Technische Universität Braunschweig, Institute for High Voltage Technology and Electrical Power Systems,
38106 Braunschweig, Germany
*

^{2}*INP Greifswald, Felix-Hausdorff-Str. 2, 17489 Greifswald, Germany
*

In this experimental investigation optical emission spectroscopy is used to characterize the radiation of the plasma in a spark gap during surge. Different approaches are used, compared and discussed in order to estimate plasma temperatures. The measurements were carried out in a narrow gap arrangement based on spark gap technology. This model is tested using 8/20 μs surge currents according to the IEC 62475 with amplitudes of 5 kA and 11 kA.

**Keywords: **
arc, temperature, plasma, spark gap, surge current, surge protective device.

* * *

**Advanced Approach for Radiation Transport Description in 3D Collisional-radiative Models**

Kalanov D.^{1}, Golubovskii Yu. B.^{1}, Uhrlandt D.^{2},
Gortschakow S.^{2}

^{1}*Saint Petersburg State University, 7/9 Universitetskaya nab., 199034 St. Petersburg, Russia
*

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

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. 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.

**Keywords: **
radiation transport, resonance radiation, plasma modelling, arcs.

* * *

**Calculation Of Pressure Rise And Energy Of Hot Gases Due
To High Energy Arcing Faults In The Metal-clad
Switchgear**

Iwata M.^{1}, Miyagi T.^{1}, Goda Y.^{1},
Shirai K.^{2}

^{1}*Central Research Institute of Electric Power Industry (CRIEPI), Electric Power Engineering Research
Laboratory, 2-6-1 Nagasaka, Yokosuka-shi, Kanagawa-ken 240-0196, Japan
*

^{2}*Central Research Institute of Electric Power Industry (CRIEPI), Nuclear Fuel Cycle Backend Research Center,
1646 Abiko, Abiko-shi, Chiba-ken 270-1194, Japan
*

This paper presents the 3-D CFD calculation results of the pressure rise due to the High Energy Arcing Faults (HEAFs) in the metal-clad switchgears. The calculations were performed considering the came-off of the roof panel that was observed in the arc tests. The calculated pressure development approximately agreed with the measured one. Furthermore, the energy of hot gases exhausted from the broken roof panel was calculated to investigate the thermal effect of hot gases.

**Keywords: **
internal arc, pressure rise, energy of hot gases.

* * *

**Experimental Stand for Investigations of Insulator
Degradation and Electrode Erosion in High-current
Breaker**

Budin A. V.^{1}, Pinchuk M. E.^{1,2}, Leontev V. V.^{1},
Leks A. G.^{1},
Kurakina N. K.^{1,1}, Kiselev A. A.^{1},
Simakova J. V.^{2,3}, Frolov V. Ya.^{2}

*
^{1}Institute for Electrophysics and Electric Power of Russian Academy of Sciences, Dvortsovaya nab., 18,
St.-Petersburg, 191186, Russia
*

^{2}Peter the Great Saint-Petersburg Polytechnic University, Polytechnicheskaya 29, St.-Petersburg 195251, Russia

^{3}NE Open Joint Stock Company, Partizanskaya , 21, St.-Petersburg, 195248, Russia

An experimental stand for studies of electric arc, electrode erosion and insulator degradation processes in high-current circuit breakers and some preliminary experimental data is described. The setup includes a discharge chamber, a capacitive energy storage with capacitance of 0.11 F, voltage up to 10 kV, and all necessary diagnostic techniques. The stand is designed for modeling current pulse with amplitude of 3–150 kA and duration of the first half period of 1.0–3.0 ms during the process of disconnecting the ring and the pin contacts. The arc is cooled by transverse gas blowing at pressure in the chamber of 0.5–3MPa. Acquired experimental data can be used for verification of the modelling results of the heat transfer processes in the discharge chamber. At the stand, advanced composite materials based on carbon and iron-copper pseudoalloy are studied.

**Keywords: **
high-current high-pressure gas discharge, electrode erosion, insulator degradation, highvoltage
test techniques, high-current circuit breaker, high-voltage engineering.

* * *

**Analysis of Arc Processes in Multi-chamber Arrester for Lightning Protection at High-voltage Overhead Power Lines**

Murashov Iu. V.^{1}, Frolov V. Ya.^{1} Uhrlandt D.^{2},
Gortschakow S.^{2}, Ivanov D. V.^{1}, Sivaev A. D.^{3}

*
^{1}Peter the Great St.Petersburg Polytechnic University, Polytechnicheskaya, 29, 195251, Saint-Petersburg, Russia
*

^{2}Leibniz Institute for Plasma Science and Technology, Felix-Hausdorff-Str. 2, 17489 Greifswald, Germany

^{3}Streamer Electric Company, Nevsky Prospect, 147, 191024, Saint-Petersburg, Russia

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.

**Keywords: **
lightning protection, electric arc extinction, arrester.

* * *

**Quantifying Uncertainties in Mean Absorption Coefficients for a Wall-Stabilized Electric Arc **

Fuchs R., Nordborg H.

*
Institute for Energy Technology, HSR University of Applied Sciences Rapperswil, Oberseestrasse 10, 8640
Rapperswil, Switzerland
*

The quality of arc simulations depends significantly on radiation modeling. Uncertainties due to physical parameters and modeling errors should be systematically quantified. We solve the energy balance equation for a wall-stabilized arc using the P1 model, i.e. without a prescribed temperature profile. We derive the linearized equation and assess the arc voltage sensitivity. This method allows us to optimize the definition of mean absorption coefficients consistently and at low computational costs.

**Keywords: **
sensitivity, mean absorption coefficient, P1 model, optimization, arc simulation.

* * *

**Synthesis of Nanosilver in Plasma-Liquid Microdischarge System**

Chernyak V.^{1}, Hamazin D.^{1}, Kolomiiets O.^{1}, Prysiazhna O.^{1},
Goriachkoa A.^{1}, Trohimchuk A.^{2}, Legenchuk O.^{2}, Lendiel V.^{1},
Fedirchyk I.^{1}

*
^{1}Faculty of Radio Physics, Electronics and Computer Systems, Taras Shevchenko National University of Kyiv,
64/13 Volodymyrska Street, 01601, Kyiv, Ukraine
*

^{2}F. D. Ovcharenko Institute of Biocolloidal Chemistry NAS Ukraine, 42 Acad. Vernadskoho Blvd., 03142, Kyiv, Ukraine

This paper presents the results of investigation of the plasma-liquid system with the
secondary discharge supported by atmospheric pressure microdischarge in the vortex Ar flow. The
plasma treated fluids were aqueous solutions of AgNO_{3}. The microplasma discharge was powered by a
DC supply. The plasma channel behaviour was characterized by photo/video recording, also plasma
was studied using emission spectroscopy technique. The working liquid and firm products created after
the treatment were studied also.

**Keywords: **
microdischarge, secondary discharge, Ag nanoparticles, plasma-liquid system.

* * *

**Post-arc Current Measurement in Mechanical Circuit
Breakers for Hvdc Applications**

Schultz T.

*
High Voltage Laboratory, ETH Zurich, Physikstrasse 3, 8092, Zurich, Switzerland
*

Post-arc currents contain valuable information on the breaker’s performance. In this paper, the dimensioning procedure for a measurement system for such currents, based on a diode clamped shunt resistor is presented. Based on synthetic low and high power tests, the performance of a mock-up is evaluated. Finally, the post-arc current of a model gas circuit breaker, designed for use in DC applications, is measured.

**Keywords: **
post-arc current, mechanical circuit breaker, small current measurement system.

* * *

**Nonequlibrium Plasma Chemistry for Concept of Sustainable Development**

Chernyak V., Nedybaliuk O., Tsymbaliuk O., Fedirchyk I., Chunikhina K., Martysh E., Iukhymenko V., Veremii Iu., Prysiazhnevych I., Prysiazhna O., Prysiazhnyi V.

*
Faculty of Radio Physics, Electronics and Computer Systems, Taras Shevchenko National University of Kyiv,
64/13 Volodymyrska Street, 01601, Kyiv, Ukraine
*

This work is devoted to the exploration of the compatibility of the hybrid plasma-catalytic conversion of liquid hydrocarbons into syngas with the concept of sustainable development. The results of experimental investigations indicate the high efficiency of plasma-catalytic conversion of ethanol to syngas and the small amount of waste (a few percent of feedstock weight). The results of the simulation of the kinetics using ZDPlasKin code for thermochemical and hybrid plasma-catalytic conversion.

**Keywords: **
sustainable development, non-equilibrium plasma chemistry, rotating gliding discharge,
conversion.

* * *

**Influence of Ablation on Differential Arc Resistance**

Bort L. S. J., Freiermuth V., Franck C. M.

*
High Voltage Laboratory, Eidgenössische Technische Hochschule, Zürich, Switzerland
*

The influence of ablation on the du/di behavior of an arc in a model gas circuit breaker
was examined. Specifically the transition from a state without ablation in the nozzle towards states
with ablation was of interest, since prior work indicated that for high currents the voltage becomes
constant or du/di gets even positive if ablation is present. Measurements with different blow pressures
and rectangular DC currents of varying amplitude were compared, using PMMA-nozzles and dry air as
blowing gas. Ablation was measured by weighing the nozzle, scanning the cross section, and using a
coordinate measuring machine. The results agreed well, and confirmed that higher pressure shifts the
d*u*/d*i* curve towards more favorable values.

**Keywords: **
axially blown arc, ablation, passive oscillation, MRTS, HVDC CB.

* * *

**Polymeric Ablation Induced by Free Burning Arcs in Air**

Bator M., Bianchetti R., Suetterlin P.

*
ABB Corporate Research Center Switzerland, Segelhofstrasse 1K, 5405 Baden-Daettwil, Switzerland
*

We investigate the influence of switching arcs on different polymers and their interaction. We describe a set of experiments on a simplified model geometry typical for low voltage switchgear. In a broad range of experimental conditions and parameters such as arc current, polymeric material or contact material, the voltage, the mass loss and the corresponding pressure build-up are examined. From this raw data, we deduce the arc influence on the ablation process as well as the feedback on some arc plasma properties.

**Keywords: **
free burning arcs, low voltage switchgear, plasma properties, polymeric ablation, thermoplastics.

* * *

**Investigation of an Ablation-dominated Arc in a Model
Chamber by Optical Emission Spectroscopy**

Methling R.^{1}, Khakpour A.^{1}, Wetzeler S.^{2},
Uhrlandt D.^{1}

*
^{1}Leibniz-Institute for Plasma Science and Technology (INP), Felix-Hausdorff-Str. 2, 17489 Greifswald, Germany*

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

A switching arc in a model chamber is investigated by means of optical emission spectroscopy. Ignition wire is applied to initiate an arc of several kiloampere between tungsten−copper electrodes. Radiation emitted by the arc plasma is absorbed by a surrounding PTFE nozzle, leading to an ablation– dominated discharge. Video spectroscopy is carried out using an imaging spectrometer combined with a high–speed video camera. Carbon ion and fluorine atom line emission from the heating channel as well as copper, oxygen and nitrogen from ignition wire and ambient air are analyzed with focus on the low–current phases at the beginning of discharge and near current zero. Additionally, electrical parameters and total pressure are recorded while the general behavior of the discharge is observed by another video camera. Considering rotational symmetry of the arc the corresponding radial emission coefficients are determined. Finally, radial temperature profiles are calculated.

**Keywords: **
circuit breaker, mathematical model, electrical switch, short circuit.

* * *

**Analysis of Last Development Results for High Voltage
Circuit-breakers Using New G ^{3} Gas**

Robin-Jouan P.^{1}, Bousoltane K.^{1}, Kieffel Y.^{1}, Trepanier J. Y.^{2},
Camarero R.^{2}, Arabi S. ^{2}, Pernaudat G.^{2}

*
^{1}General Electric Grid Solutions, France*

^{2}Ecole Polytechnique de Montréal, Quebec

Among many alternative gases proposed to replace SF6 as insulating gas, g^{3} (green gas
for grid), fluoronitril based component officially introduced at CIGRE 2014, can be now used for
insulation projects and new environmental friendly circuit breakers. This gas mixture g^{3}, presents a
reduction of the global warming potential by 98% compared to SF_{6} gas and shows quite good dielectric
withstand capability. Many new investigations about thermal and chemical behavior have been done
and are precised in this paper. Last switching test campaigns will be presented for 145 kV applications.
Simulation tools should be updated to be applicable to these projects. Developments and comparisons
with last test results will be analyzed

**Keywords: **
SF_{6} alternative gases, CO_{2}, Circuit Breaker, g^{3}.

* * *

**Analysis of Electromagnetic Processes Inside the Arc
Interrupting System of a High-current Circuit Breaker**

Murashov I.^{1}, Frolov V.^{1}, Ivanov D.^{1},
Kvashnin A.^{2}

*
^{1}Department "Electrical Power Engineering and Equipment", Peter the Great Saint-Petersburg Polytechnic
University, 29 Polytechnicheskaya, 195251 Saint-Petersburg, Russia*

^{2}NE Open Joint Stock Company, 21 Partizanskaya, 195248 Saint-Petersburg, Russia

Description of electromagnetic processes inside an arc interrupting system of high-current circuit breaker is presented in article. Non-stationary mathematical model of the circuit-breaker operation (short-circuit currents mode) is developed. The main regularities of the displacement of the electric arc inside an arc chute are established. The influence of the movable contact position on the conditions for the displacement of the electric arc is presented. Also, the influence of the arc chute material on the motion and interrupting of an electric arc (alternating and direct currents) is established.

**Keywords: **
ablation, switching arc, spectroscopy.

* * *

**Investigating of the Recovery Behaviour of a Small Switching Gap after Current Interuption**

Bosche D., Alija M., Hilbert M., Kurrat M.

*
Institute for High Voltage Technology and Electrical Power Systems - elenia, TU Braunschweig,
Schleinitzstrasse 23, 38106 Braunschweig, Germany
*

The recovery behaviour of switching arcs in a small gap was investigated experimentally. Therefore a simple mechanical model switch without an arcing chamber was designed. For the investigation the current carring contacts are separated. After various arcing times, the current is interrupted by an electronic switch. At a fixed contact distance, the switching gap was tested with variable voltages to investigate the dielectric strength. Based on these results the recovery behaviour was studied using the Weibull distribution function.

**Keywords: **
plasma temperature, switching gap, arc, current zero, reignition, Weibull distribution.

* * *

**Application Of Rf (13.56 MHz) Arc Discharge For Plasma
Chemical Conversion Of Volatile Fluorides**

Kornev R. A.^{1}, Sennikov P. G..^{1}, Nazarov V. V..^{2}

*
^{1}G.G. Devyatykh Institute of Chemistry of High-Purity Substances of RAS, Nizhny Novgorod, Russia*

^{2}Institute of Applied Physics RAS, Nizhny Novgorod, Russia

The report discusses the use of a new type of plasma source of hydrogen plasma based on a RF (13.56 MHz) arc discharge of atmospheric pressure between two electrodes. This discharge was used for hydrogen reduction of the tetrafluorides of silicon, boron and molybdenum. As a result of the studies, the main regularities of the hydrogen reduction process were established and the main synthesized products were determined. Samples of carbides of silicon, boron and molybdenum were prepared.

**Keywords: **
RF arc discharge, boron fluoride, silicon fluoride, molybdenum fluoride.

* * *

**Rotating Constricted Switching Arcs Burning in Gas and
in Vacuum**

Baron D.^{1}, Ettingshausen S.^{1}, Koletzko M.^{3},
Lawall A.^{b}, Rettenmaier T.^{3}, Wenzel N.^{3}

*
^{1}Siemens AG, Energy Management, Medium Voltage & Systems, Frankfurt am Main, Germany*

^{2}Siemens AG, Energy Management, Medium Voltage & Systems, Berlin, Germany

^{3}Siemens AG, Corporate Technology, Erlangen, Germany

The method of controlling high-current switching arcs by transverse magnetic fields (TMF) forcing the constricted arc to rotate in a contact system is being applied successfully to improve the breaking capability of vacuum interrupters and gas circuit breakers. We describe the behavior of magnetically driven switching arcs in vacuum and in gas environment. We report on experiments using high-velocity videography, magnetic probes, and spectroscopy; they deliver the velocity, the temperature and the voltage of an arc. We present models and simulations of the moving constricted arc burning in metal vapor and in air. And we describe a particular switching application of TMF arc control and explain a scaling law of the contact size with the current interruption capability.

**Keywords: **
constricted arc, vacuum arc, gas arc.

* * *

**An Efficient Implementation of the Finite-volume Method
For the Solution of Radiation Transport in Circuit
Breakers**

Mazaheri A.^{1}, Trepaniera J. Y.^{1}, Camarero R.^{1},
Robin-Jouan P.^{2}

*
^{1}École Polytechnique de Montreal, 2900 boul. Edouard-Montpetit, Campus de l'Universite de Montreal, 2500
chemin de Polytechnique, Montreal (Quebec), H3T 1J4, Canada*

^{2}GE Grid-Solutions, Villeurbanne, France

In this paper, we propose to revisit the method to solve the radiation transport equation in circuit breakers to reduce the computation time. It is based on an explicit approach using a space marching algorithm. The method can further be accelerated using a Cartesian grid and using the axisymmetric assumption. Comparisons performed in terms of accuracy and efficiency between the P1 model, the implicit finite-volume discrete ordinate method and the space-marching finite-volume discrete ordinate method show that the explicit approach is more that an order of magnitude faster than the implicit approach, for the same accuracy.

**Keywords: **
radiation, circuit-breaker, finite-volume method, space-marching.

* * *

**Development of Current Limiting Device for Short and
Autonomous Networks**

Vostrov K., Frolov V., Safonov E.

*
Department of Electrical Power Engineering and Equipment, Peter the Great Saint-Petersburg Polytechnic
University, Polytechnicheskaya 29, 195251 St. Petersburg, Russia
*

In this paper, the problem of tripping of high values of short-circuit currents in mediumvoltage networks will be considered. Disconnection of short-circuit currents which can reach 100–300 kA in short networks is difficult task for modern switching equipment due to the impossibility of damping the electric arc generated by such currents, and due to strong thermal and electrodynamic effects on elements of the switching device. Solution based on active current limiting reactor will be presented.

**Keywords: **
current limiting, short circuit, arcless commutation, arc extinction.

* * *

**Vacuum Arc Ion Flux From Vacuum Interrupter Contact Gap**

Kurrat M.

*
Technische Universitaet Braunschweig, Institute for High Voltage Technology and Electrical Power Systems
Schleinitzstrasse 23, 38106 Braunschweig, Germany
*

Dielectric properties of vacuum interrupters are influenced by metal vapour deposition on the inner ceramic surfaces. Therefore these surfaces are partly protected by shield electrodes. The metal vapour originates from the vacuum arc in the contact gap during switching off process. Metal layer thickness on ceramics after switching operations were measured by Gramberg and the negative effect on dielectric performance was demonstrated. In this paper we address the principle transport process of metal vapour in vacuum interrupters. Duning and Beilis performed ion flux measurements from vacuum arcs. We regard experiments with 5 kA effective arc current. There seems to be experimental evidence that the final particle transport onto the ceramic surface within a shield gap can be explained by particle tracing. The measured deposited layer thickness is taken as quantity to validate vapour densities and transport processes in vacuum interrupters.

**Keywords: **
vacuum interrupter, vacuum arc, ion flux, metal vapour, layer deposition, particle tracing.

* * *

**Determination of Cr Density in the Active Phase of a High-current Vacuum Arcs**

Gortschakow S.^{1},Khakpour A.^{1}, Popov S.^{2},
Franke St.^{1}, Methling R.^{1}, Uhrlandt D.^{1}

*
^{1}Leibniz Institute for Plasma Science and Technology e.V. (INP Greifswald), Felix-Hausdorff-Str. 2, 17489
Greifswald, Germany
*

^{2}Institute of High Current Electronics, Siberian Branch of the Russian Academy of Sciences, Tomsk 634055, Russia

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 425.43nm 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.

**Keywords: **
vacuum arc, anode spot, absorption spectroscopy.

* * *

**Interruption of Weakly Cooled Arcs in Air and Airplus**

Ranjan N., Carstensen J., Scheel S.

*
ABB Switzerland Ltd, Corporate Research, Segelhofstrasse 1, 5405 Baden-Dattwil, Switzerland
*

Switching of low current arcs in free burning or weakly cooled conditions is mainly
determined by the thermal properties of the gas. Products with such switching conditions are widely
found in secondary distribution medium voltage (MV) gas insulated switchgears (GIS). In this study,
we compare the current interruption capability of synthetic air and AirPlus^{TM}, i.e. a mixture of
synthetic air with C_{5}F_{10}O fluoroketone (C5-FK). We focus on thermal interruption performance of the
gases. AirPlus mixture corresponds to -25°C condensation temperature of C5-FK. An arc is drawn
between the contacts and cooled by blowing cold gas from a tank. Blowing pressure required for current
interruption is compared. Within the measurement accuracy, the current interruption performance of
both gases is similar. Chemical analysis of the AirPlus mixture after 69 shots was performed using Gas
Chromatography Mass Spectroscopy (GCMS) and it shows very little decrease in the concentration of
C5-FK.

**Keywords: **
weakly cooled arcs, load break switches, C5-FK, thermal interruption.

* * *

**Modeling of Perfluorocarbons Decomposition in Nitrogen Thermal Plasma**

Chau S. W.^{1}, Chen S. H. ^{2}

*
^{1}Department of Engineering Science and Ocean Engineering, National Taiwan University, 1, Sec. 4, Roosevelt
Rd., 10617 Taipei, Taiwan, ROC
*

^{2}Physics Division, Institute of Nuclear Energy Research, 1000 Wenhua Rd., Longtan, 32546 Taoyuan, Taiwan, ROC

This paper develops an axisymmetric flow model to predict the flow field inside a directcurrent plasma torch reactor, where the magneto-hydrodynamic equations, including the continuity, momentum, energy and current continuity equations as well as turbulence transport equations are solved with a finite volume discretization in a segregated manner. The thermodynamic and transport coefficients of thermal plasma are obtained from the condition of local thermal equilibrium, whereas a kinetics model is employed to consider the production and destruction of species due to the chemical reactions in a decomposition process. Species transport phenomena arising in the decomposition process are described by the transport equations for different species. The perfluorocarbons decomposition characteristics in a well-type, non-transferred nitrogen torch reactor are analyzed by the proposed numerical model to disclose the influence of working parameters on the decomposition efficiency.

**Keywords: **
perfluorocarbons decomposition, nitrogen, thermal plasma, direct-current, plasma torch.

* * *

### Number 1

**Contact and Nozzle Wear from 100 Interruptions for a Puffer-Type Air Load Break Switch**

Stoa-Aanensen N., Jonsson E., Runde M.

*
SINTEF Energy Research, 7465, Trondheim, Norway
*

One type test requirement for medium voltage load break switches is to interrupt 100 consecutive "mainly active loads". A puffer-type switch with axial-blown arc has been tested according to the 630 A/24 kV ratings. The nozzle and contact wear were measured regularly to investigate design requirements and the impact from nozzle wear on gas flow. The contact wear is only moderate, while the nozzle wear causes a decrease in pressure build-up, which in turn may influence the interruption performance.

**Keywords: **
load break switch, switchgear, medium voltage, electric arc, puffer switch, nozzle wear

* * *

**Investigation of Pulse Glow Discharge Excitation Modes in N _{2} in a Hollow Cylindrical Combined Cathode**

Bordusau S. Madveika S., Bozhko A., Tsikhan O.

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

Electric discharge excitation modes and N_{2}
pressure range for a stable formation and maintaining
of pulse glow discharge plasma in a hollow combined cathode
have been investigated. It has been found that both of
these parameters are influenced by the constructive
peculiarities of the cathode. It has been established
experimentally that the value of N_{2} breakdown voltage
for the studied construction of the cathode within the range
of 50-250 Pa does not exceed -700 V.

**Keywords: **
hollow cathode, glow discharge, electric pulses, vacuum

* * *

**Recent Trends in Development of High Voltage Circuit Breakers with SF _{6} Alternative Gases**

Seeger M.^{1}, Smeets R.^{2}, Smeets R.^{2},
Yan J.^{3}, Ito H.^{4}, Claessens M.^{1},
Dullni E.^{5}, Falkingham L.^{6}, Franck C. M.^{7},
Gentils F.^{8}, Hartmann W.^{9}, Kieffel Y.^{10},
Jia S.^{11}, Jones G.^{3}, Mantilla J.^{1},
Pawar S.^{12}, Rabie M.^{7}, Robin-Jouan P.^{10},
Schellekens H.^{8}, Spencer J.^{3}, Uchii T.^{13},
Li X.^{11}, Yanabu S.^{11}

^{1}ABB Switzerland Ltd, Corporate Research Center, Segelhofstrasse 1K, CH-5405 Baden-D\"attwil, Switzerland

^{2}DNV GL, Utrechtseweg 310, 6800 ET, Arnhem, Netherlands

^{3}University of Liverpool, Department of Electrical Engineering and Electronics, Liverpool, L69 3GJ, UK

^{4}Mitsubishi Electric Corp., Tokyo Building 2-7-3, Marunouchi, Chiyoda-ku, Tokyo 100-8310, Japan

^{5}ABB AG, Bahnstrasse 39-4, D-40832 Ratingen, Germany

^{6}Vacuum Interrupters Limited, Sir Frank Whittle Business Centre, Great Central Way, Rugby CV21 3XH, UK

^{7}ETH Z\"urich, R\"amistrasse 101, 8092 Z\"urich, Switzerland

^{8}Schneider Electric, 35, rue Joseph Monier, 92500 Rueil-Malmaison, France

^{9}Siemens AG, Corp.Techn., Otto-Hahn-Ring 6, 81739 Munich, Germany

^{10}GE Grid Solutions, 51 Espl. du General de Gaulle, 92900 Puteaux, France

^{11}Xi'an Jiaotong University, 28 Xianning West Road, Beilin, Xi'an, Shaanxi, China

^{12}Crompton Greaves, Dr. Annie Besant Road, Worli, Mumbai -- 40001, India

^{13}Toshiba Corp., Power and Industrial Systems R\&D Center, 8 Shinsugita-cho, Kanagawa 235-8523, Japan

The available knowledge of state-of-the-art of SF_{6} alternative gases
in switching applications was collected and evaluated in
an initiative of the Current Zero Club together with CIGRE.
The present contribution summarizes the main results of this
activity and will also include the latest trends. The main
properties and switching performance of new gases are compared
to SF_{6}. The most promising new gases are at the moment
perfluoroketones and perfluoronitriles. Due to the high boiling
point of these gases, in HV applications mixtures with CO_{2}
are used. For MV insulation perfluoroketones are mixed with air,
but also other combinations might be possible. The dielectric and
switching performance of the mixtures, with mixing ratios that allow
sufficiently low operating temperatures, is reported to be only
slightly below SF_{6}. Minor design changes or
de-rating of switchgear are therefore necessary. Differences
between the gas mixtures are mainly in the boiling point and
the GWP.

**Keywords: **
SF_{6} alternative gases, CO_{2}, circuit breaker

* * *

**The Influence of Microwave CF _{4} Plasma Activation on the Characteristics of Reactive Ion Etching of Mono-Si**

Bordusau S., Madveika S., Lushakova M., Kovalchuk N.

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

The experiments have shown that microwave preliminary ionization of the plasma-forming gas increases the rate of the reactive ion etching of monocrystalline silicon (mono-Si) by four and more times in comparison with the etching process without it. It is established that the mode of plasma activation (the power of microwave discharge) and the value of plasma-forming gas pressure significantly affect the characteristics of mono-Si surface micro-roughness obtained in the result of etching.mixtures are mainly in the boiling point and the GWP.

**Keywords: **
microwave discharge, activation, etching, roughness, surface

* * *

**Investigation of Vacuum Arc Anode Temperatures of Cu-Cr and Pure Cu Contacts**

Franke St.^{1}, Methling R.^{1}, Gortschakow S.^{1}, Abplanalp M.^{2}, Sutterlin R.-P.^{2},
Delachaux T.^{2}, Menzel K. O.^{2}

^{1}INP Greifswald, Felix-Hausdorff-Str. 2, 17489 Greifswald, Germany

^{2}ABB Corporate Research, ABB Switzerland, Segelhofstrasse 1K, 5405 Baden-D\"attwil, Switzerland

The present contribution reports on investigations of electrode temperatures for pure Cu electrodes and Cu-Cr electrodes of different diameters exposed to vacuum arcs with sinusoidal currents of 5-15 kA and an axial magnetic field up to 180$nbsp;mT. It is found that surface temperatures of pure Cu electrodes are significantly lower than for Cu-Cr electrodes of the same diameter. This must be explained by different thermal properties of both materials. Reducing the diameter of Cu-Cr electrodes it is found that surface temperatures increase, but moreover it is shown that the enthalpy stored in the electrode bulk material may effect electrode temperatures on timescales much longer than the current pulse width, particularly if there is no effective heat dissipation after current zero.

**Keywords: **
vacuum arc, anode temperature, thermography

* * *

**Utilisation of the High Speed Camera for the Pin-hole Discharge Diagnostics**

Kozakova Z., Krcma F., Drimalkova L., Hlochova L.

*
Faculty of Chemistry, Brno University of Technology, Purkynova 118, 612 00 Brno, Czech Republic*

The high speed camera was utilised for plasma diagnostics of the DC pin-hole discharge in electrolyte solutions. Two discharge modes were determined. Plasma channels were observed either in the bubble or outside the bubble in the bulk solution, which confirms both thermal and electron theory of the discharge ignition in liquid. In the diaphragm discharge, plasma streamers were better visible on the cathode side of the dielectric barrier because they formed significantly longer channels.

**Keywords: **
discharge in liquid, pin-hole discharge, high speed camera, plasma diagnostics

* * *

**Experimental Investigations on Electrical Plasma Conductivity in a Model Spark Gap for Surge Currents**

Runge T., Kopp T. H., Kurrat M.

*Technische Universitat Braunschweig, Institute for High Voltage Technology and Electrical Power Systems, 38106 Braunschweig, Germany
*

In this experimental investigation the electrical conductivity of plasma is measured during surge current using potential probes. The measurements were carried out in a narrow gap arrangement based on spark gap technology. In order to investigate the electrical conductivity during surge this model is tested using 8/20%nbsp;$mu;s surge currents according to the IEC 62475. The measured behaviour of the electrical conductivity during surge and the uncertainty of these measurements are discussed.

**Keywords: **
arc, electrical conductivity, plasma, spark gap, surge current, surge protective device

* * *

**Plasma Assisted Generation of Micro- and Nanoparticles**

Veklich A.^{1}, Lebid A. Lebid^{1}, Tmenova T.^{1}, Boretskij V.^{1},
Cressault Y.^{2}, Valensi F.^{2}, Lopatko K.^{3}, Aftandilyants Y.^{3}

^{1}Taras Shevchenko National University of Kyiv, 64/13, Volodymyrska str., Kyiv, Ukraine

^{2}Universite de Toulouse; UPS, INPT; LAPLACE (Laboratoire Plasma et Conversion d'Energie); 118 route de Narbonne,
F-31062 Toulouse Cedex 9, France

^{3}National University of Life and Environmental Sciences of Ukraine, Kiev, Ukraine

In this research, the peculiarities of micro- and nanoparticles generation are considered. Two techniques of micro- and nanoparticles' formation using electric arc and underwater discharge plasma sources are proposed.

Molybdenum oxide crystals were deposited on side surface of the bottom electrode (anode)
of the free-burning discharge between metallic molybdenum electrodes. Friable layer of MoO_{3}, which consists of variously
oriented transparent prisms and platelets (up to few hundreds of $mu;m in size), was formed by vapor deposition around the
electrode. In the second technique, plasma of the underwater electric spark discharges between metal granules was used
to obtain stable colloidal solutions with nanoparticles of 20-100 nm sizes.

**Keywords: **
molybdenum trioxide, plasma evaporation, underwater spark discharge, colloidal liquids

* * *

**Changing the Surface Properties of ABS Plastic by Plasma**

Chlupova S., Kelar J, Slavicek P.

*Department of Physical Electronics, Masaryk University, Kotlarska 2, 602 00 Brno, Czech Republic*

The research deals with plasma treatment of acrylonitrile butadiene styrene plastic (ABS). The plastic was treated with Diffuse Coplanar Surface Barrier Discharge (DCSBD) and Gliding arc at atmospheric pressure. ABS was chosen because of its low price, wide use in industry. Samples were analyzed with contact angle measurement and the surface energy was determined as well. The results show that only a few seconds of plasma treatment can cause relatively large wettability change.

**Keywords: **
plasma, surface treatment, DCSBD discharge, ABS plastic,
contact angle, surface energy

* * *

**Properties of Vacuum Arc Influenced by Electrode Diameter and Material in TMF Contact Based on Forced Current Zero**

Wenlei Huo^{1}, Jianwen Wu^{1}, Yun Deng^{1}, Xinchen Jin^{1}, Liying Zhu^{2}

^{1}School of Automation Science and Electrical, Beihang University, Beijing 100191, China

^{2}Institute of Spacecraft System Engineering CAST, Beijing 100094, China

With the increase in electrical equipment in More/All Electric Aircraft, 270V dc power supply systems will be needed. One method for DC interruption is forced current zero (FCZ). Based on FCZ technology with transverse-magnetic-field (TMF) contact, the spiral-type contacts are designed. Experiments with different currents are carried out with contact diameters being 30 mm, 40 mm, and 50 mm, and arcing surface materials Cu-W80 alloy and Cu-Cr50 alloy respectively. It is indicated by the experimental results that breaking capacity of vacuum interrupter and vacuum arc appearance are closely related to the electrode diameter and material. For the same size of electrode diameter, the breaking capacity in Cu-Cr50 is better than that in Cu-W80. With increasing electrode diameter, arc column expansion velocity and diameter increase gradually. Breaking capacity is increasing with larger contact diameter.

**Keywords: **
vacuum arc, forced current zero, transverse magnetic field, breaking capacity, electrode diameter and material

* * *

**Calculation of Arc Power Losses in the Simplified Model of Intensively Blasted Electric Arc**

Senk J., Laznickova I., Jakubova I.

In previous versions of the simplified model of intensively blasted electric arc burning in argon in the arc heater's anode channel, the authors used the constant total power loss coefficient for estimation of arc power losses in all anode channel individual parts. Using this approach, the model with relatively low computational complexity has led to very good agreement between the total computed and experimentally obtained values, but when the computed and measured power losses of individual anode channel segments have been compared, considerable differences have been revealed. In the modified model, theoretically computed net emission coefficient of argon is used in the energy equation to express the arc power losses. This way, satisfactory accordance is achieved between not only the total, but also partial measured and computed values. Exemplary results are given in figures and tables and discussed.

**Keywords: **
electric arc, model, experiment, power loss, net emission coefficient

* * *

**Optical Diagnostics of Switching Arcs Near Current-zero: Speckle Imaging and Interferometry**

Stoller P. C., Carstensen J., Galletti B., Doiron C. B., Sokolov A.

*
ABB Switzerland Ltd., Segelhofstrasse 1K, 5405 Baden-Daettwil, Switzerland *

Optical diagnostics can be used to obtain spatially resolved measurements of the density, temperature, conductivity, and electron density of circuit breaker arcs embedded in transonic flows; these can be used to validate the results of simulations, the accuracy of which can currently be assessed in only a limited way. We compare speckle imaging and an interferometric approach. Both use a pulsed nanosecond laser. The speckle imaging setup does not require a reference beam, but only yields information about the gradient of the refractive index. Its accuracy is sensitive to the alignment of the optical components. Interferometry directly yields high resolution images of the index of refraction, from which the density can be calculated using the Gladstone-Dale relation. By using two laser beams, interferometry provides spatially resolved information about the electron density. Such measurements are a significant step towards more accurate CFD models.

**Keywords: **
circuit breaker, current-zero, interferometry, imaging, density, temperature

* * *

**Numerical Analysis of low voltage Arc Motion Process at Various Frequencies**

Yin J.^{1}, Li X.^{1}, Wang Q.^{2}

^{1}State Key Laboratory of Electrical Insulation and Power Equipment, Xi $'$an Jiaotong University, Xi $'$an, Shaanxi, 710049, China

^{2}School of Sciences, Xi'an University of Technology, Xi'an, Shaanxi, 710048, China

A three-dimensional (3D) magneto-hydro-dynamic (MHD) model of air arc plasma is built to investigate the frequency effects on the arc motion process with different number of splitter plates. Based on this model, the arc voltage and current density are obtained. The arc motion time is normalized with the frequency and compared at different numbers of splitter plate. The result shows that the normalized time and the arc voltage peak increase with increases of the number of splitter plate.

**Keywords: **
magneto-hydro-dynamic (MHD), eddy current, frequency, motion process

* * *

**Influencing Factors on the Dielectric Breakdown Strength in F-gas Free High-voltage Switchgear**

Gossmann S.^{1}, Lutz B.^{2}, Nikolic P. G.^{1}

^{1}Siemens AG, Corporate Technology, G\"unther-Scharowsky-Str.1, 91058 Erlangen, Germany

^{2}Siemens AG, Energy Management, Nonnendammallee 104, 13629 Berlin, Germany

After being in the focus of sciences' and industry's research and development activities for many years, the investigation of possible SF_{6} gas-alternatives has been even more intensified
after the revision of the European regulation on fluorinated gases in 2014. In this contribution the influencing factors on the dielectric
breakdown of clean air are investigated for weak inhomogeneous field and gas pressures up to 10 bar. Modelling approaches and experimental data are compared.

**Keywords: **
F-gas free switchgear, dielectric breakdown, clean air, surface roughness

* * *

**Analysis of Radiation Discretization for Modelling a Spark Gap for Surge Currents**

Sander C.^{1,2}, Schmutz J.-E.^{1}, Kurrat M.^{2}

^{1}PHOENIX CONTACT GmbH \& Co. KG, Flachsmarktstra�e 8, D-32825 Blomberg, Germany

^{2}Institute for High Voltage Technology and Electrical Power Systems, Technical University Braunschweig, Schleinitzstra�e 23, 38106 Braunschweig, Germany

In this paper we address a method for spectrally resolved radiation modelling in thermal plasmas encountered in surge protective devices based on spark gaps. Compared to most switching applications, power input and plasma pressure are much higher which leads to an optically thick plasma with line broadening and enhanced wall ablation. In this situation it is possible to capture the full effect of spectrally resolved radiation on plasma dynamics by performing line-by-line calculations with downsampled absorption spectra. We show that it is possible to achieve radiation convergence with 1000 lines. Approaches for a further reduction of calculation times using band-averaged models and $\kappa$-group models are discussed. The κ-group model is based upon a grouping of the absorption coefficients into subgroups with different ranges of κ before averaging. The spectral calculation results are compared to the approximative methods and significant differences for Rosseland means are observed.

**Keywords: **
spark gap, radiation, spectral, simulation, arc, surge protective device

* * *

**Experimental Study on Arcing Effects to Contact Materials in 270V dc**

Zhu Q.C.^{1}, Li Z.B.^{1}, Wei J.^{1}, Liu Z.X.^{1}, Huang J.^{1},
Zhang D.D.^{1}, Hasegawa M.^{2}

^{1} State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong Univ.of Science and Technology, 430074, Wuhan, China

^{2}Chitose Institute of Science and Technology, 066-8655, Chitose, Hokkaido, Japan

As supply DC voltage levels in automobiles, aviation and aerospace are becoming higher, high voltage and large capacity compact DC electromagnetic relays or contactors are becoming more important. In this paper, experiments were conducted at DC 270V/100A in air and nitrogen, respectively, with CuCr40, CuCr45, CuCr50, CuW60, CuW70 and CuW90 as contact materials. Welding resistance (corresponding to electrical contact life), contact erosion and breaking arc durations were measured, and the obtained results were discussed.

**Keywords: **
contact materials, DC voltage, arcing duration, welding, erosion, relay

* * *

**Device for Protection Against Transient and Temporary Overvoltage Including Limitation of the Specific Energy**

Ehrhardt A., Buhler K. B

*DEHN + SOHNE GmbH + Co.KG., Hans-Dehn-Strass e 1, D-92318 Neumarkt, Germany*

An arrangement is presented which ensures protection against transient and line frequency overvoltage and limits the load on the consumer to a minimum even in case of transient currents. The arrangement consists of a special arrester in the shunt circuit, a fast switch in the series circuit as well as a control and measuring device. The design, mode of operation and parameters of the components of the arrangement are described based on different loads. The protective effect is discussed.

**Keywords: **
overvoltage protection, surge protection, spark gap, semiconductor switch

* * *

**Optimal Band Selection for the Calculation of Planck Mean Absorption Coefficients**

Gnybida M.^{1}, Rumpler Ch.^{2}, Narayanan V. R. T.^{1}

^{1}Eaton European Innovation Center, Borivojova 2380, 252 63 Roztoky, Czech Republic

^{2}Eaton, 1000 Cherrington Pkwy Moon Township, PA 15108, USA

Radiative heat transfer is a major heat loss mechanism in thermal plasmas generated during arc flashes/faults in switchgear applications or
during high current interruption in low voltage circuit breakers. A common way to calculate the radiation balance
is by means of approximate non-gray radiation models like P1 or discrete ordinates (DOM), where the frequency dependent absorption
and emission are described in a number of frequency intervals (bands) using a constant absorption coefficient in each band.
Current work is focused on finding the optimal number of bands as well as band interval boundaries that provide a
reasonable level of accuracy in comparison to a full spectral solution. An optimization procedure has been applied to different SF_{6}
and copper vapor gas mixtures for an assumed temperature profile. Radiation model results using optimized band averaged absorption coefficients
as well as spectral values are provided and discussed for the exemplary temperature profile.

**Keywords: **
radiation, thermal plasma, circuit breaker, SF_{6}

* * *

**Chemical and Electron Interaction Properties of Potential Gaseous Insulation and Arc-quenching Media**

Lili Zhu, Dongxian Tanand, Su Zhao, Dengming Xiao

*Department of Electrical Engineering, Shanghai Jiao Tong University, No.1954 Huashan Rd., 200030,Shanghai, People's Republic of China*

The global warming effects of sulphur hexafluoride (SF_{6}) lead researchers to look for new environmentally-friendly gas media in high-voltage electrical apparatus. The present paper discusses basic chemical and electron interaction properties that brings high insulation strength and good arc interruption capability for a gas. The conclusion shows that gaseous compounds composed of elements in the upright area of periodic table of elements generally have stronger electronegative ability and good electrical properties. And double bond or triple bond in gas molecule can effectively improve the dielectric strength. For gas mixtures, good cooperation of gases will generate synergetic effect, which makes its dielectric strength higher than the weighted average value of each gas. Some aspects in searching for new arc interruption media are also discussed.

**Keywords: **
chemical property, electron interaction, insulation, arc interruption

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**Towards an Efficient Arc Simulation Framework**

Fuchs R., Murmann M., Nordborg H.

Arc simulations require a coupled solution of the flow and electromagnetic equations. Despite of industrial interest, there is no established simulation framework available yet. We assess the usability of STAR-CCM+ for low voltage circuit breaker simulations using a test case of a model arc chamber, since this toolkit allows to define and control the simulation in a single environment. In spite of a partially implemented arc root model, the results agree well with reference data of previous publications.

**Keywords: **
arc simulation,
arc root model,
splitter plates,
low voltage circuit breakers,
computational magnetohydrodynamics

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**Diagnostics of Nitrogen-methane Atmospheric Glow Discharge Used for a Mimic of Prebiotic Atmosphere**

Mazankova V.^{1}, Torokova L.^{1}, Trunec D.^{2}, Krcma F.^{1},
Matejcik S.^{3}, Mason N. J.^{4}

^{1}Faculty of Chemistry, Brno University of Technology, Purkynova 118, 612 00 Brno, Czech Republic

^{2}Faculty of Science, Masaryk University, Kotlarska 2, 611 37 Brno, Czech Republic

^{3}Faculty of Mathematics, Physics and Informatics, Comenius University, 842 48 Bratislava, Slovakia

^{4}Department of Physical Sciences, Open University, Walton Hall, Milton Keynes MK7 6AA, UK

The exploration of planetary atmosphere is being advanced by the exciting results of
the Cassin-Huygens mission to Titan. The complex chemistry revealed in such atmospheres leading to the
synthesis of bigger molecules is providing new insights into our understanding of how life on Earth developed.
This work extends our previous investigation of nitrogen-methane (N_{2}-CH_{4}) atmospheric glow
discharge for simulation chemical processes in prebiotic atmospheres. In presented experiments 2 %
of water vapor were addet to nitrogen-methane gas mixture. Exhaust products of discharge in
this gas mixture were in-situ analysed by Fourier Transform Infra Red spectroscopy (FTIR). The major products identified in spectra were: hydrogen cyanide, acetylene and acetonitrile.

**Keywords: **
prebiotic atmosphere, Fourier Transform Infra Red spectroscopy, glow discharge

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**Implosive Thermal Plasma Source for Energy Conversion**

Sonsky J.^{1}, Tesar V.^{1}, Gruber J.^{1}, Maslani A.^{2}

^{1}Institute of Thermomechanics of The Czech Academy of Sciences, Dolejskova 1402/5, 182 00 Prague, Czech Republic

^{2}Institute of Plasma Physics of The Czech Academy of Sciences, Za Slovankou 1782/3, 182 00 Prague, Czech Republic

Laboratory scale thermal plasma source for magnetohydrodynamic or magnetocumulative generator was developed. The thermal plasma is created from combustible stochiometric mixture of hydrogen and oxygen by spherical implosion of convergent detonation wave. Resulting high velocity plasma is observed by capturing emitted light by hi-speed camera to determine plasma velocity and also spectroscopically in order to estimate of plasma temperatures. Construction of the implosion plasma source is discussed.

**Keywords: **
implosion, thermal plasma, detonation wave

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**Study of the Insulating and Arc-quenching Performance of CO _{2} and Its Mixtures: A Brief Review**

Zhao H.^{1}, Gu W.^{2}, Li X.^{3}

^{1}School of Automation, Northwestern Polytechnical University, Xi $'$an, Shaanxi, 710072, China

^{2}Sieyuan Electric Co., Ltd. Shanghai, 201108, China

^{3}State Key Laboratory of Electrical Insulation and Power Equipment, Xi $'$an Jiaotong University, Shaanxi, 710049, China

SF_{6}, which is widely used as an insulating or arc-quenching medium in electrical apparatus, has a strong global warming potential.
Recently, CO_{2} and its mixtures attract great attention as a promising alternative gas. This paper presents our calculation and measurement
results on the insulating and arc-quenching capabilities of CO_{2} and its mixtures, including the discharge parameters, arc characteristics,
post-arc breakdown properties, and arc-quenching capabilities. On the basis of our study and other published literatures, a discussion of and perspectives on current research and future research directions are presented as well.

**Keywords: **
insulating, arc-quenching, CO_{2}

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**Investigation on the Influence of Gas Pressure on CO _{2} Arc Characteristics in High-Voltage Gas Circuit Breakers**

Guo Z., Li X., Zhang Y., Guo X., Xiong J.

* State Key Laboratory of Electrical Insulation and Power Equipment, Xi $'$an Jiaotong University, Xi $'$an 710049, China*

CO_{2} is identified as a promising alternative gas of SF_{6}. The magnetohydrodynamics (MHD) arc model is established for a CO_{2} circuit breaker.
The influence of gas pressure is studied. The simulations are carried out for 0.5 MPa, 0.7 MPa and 0.9 MPa absolute filling pressure,
allowing predictions of pressure and temperature distributions. The arc time constant θ and the power loss coefficient *Q* is extracted.
The thermal interruption capability is estimated to grow with increasing filling pressure.

**Keywords: **
CO_{2}, gas pressure, circuit breaker, Mayr equation

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**Evolution of the Cathode Spot Distribution in an Axial Magnetic Field Controlled Vacuum Arc at Long Contact Gap**

Tezenas du Montcel B.^{1,2}, Chapelle P.^{1}, Jardy A.^{1}, Creusot C.^{2}

^{1}Institut Jean Lamour - UMR 7198 CNRS/Universit'e de Lorraine, Laboratoire d'Excellence DAMAS, CS 50840, 54011 Nancy Cedex, France

^{2}SuperGrid Institute SAS, 130 rue Leon Blum, BP1321, 69611 Villeurbanne, France

The distribution of cathode spots in a CuCr25 vacuum arc controlled by an axial magnetic field and ignited on the lateral surface of the cathode is investigated for long gap distances, from the processing of high-speed video images. The processing method includes also estimating the current carried by a single spot and reconstructing the distribution of the current density at the cathode. Various distributions depending partly on the arc current are described.

**Keywords: **
vacuum arc, axial magnetic field, long gap, cathode spot distribution, experimental study

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**Feedbacks in Non-equilibrium Oxidative Plasma Reacting with Polyethylene**

Kadnikov D. V., Ovtsyn A. A., Shibaev S. A. Smirnov S. A

*Department of technology devices and materials for electronic equipment, Ivanovo State University of Chemistry and Technology, Sheremetevsky Avenue 7, 153000, Ivanovo, Russia
*

The experimental results on studies of loading effect at the action of a glow DC
discharge in oxygen and air on polyethylene film are presented. At the increase
in a polymer amount under a treatment the specific rates of etching and CO_{2}, CO, H_{2}O, H_{2} product formation rates are decreased. The gas temperature is changed slightly. The reduced electric field strength is increased in oxygen plasma and decreased in air plasma.

**Keywords: **
air plasma, oxygen plasma, loading effect, gas temperature, reduced electric field strength, polyethylene

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