The work presents a comprehensive study of thermal plasma of electric arc discharge between composite electrodes of compositions Mo-50Cu-2Al2O3, Mo-50Cu-2Y2O3 and Mo-50Cu-5Y2O3 (in wt.%). The experiments were carried out in an argon flow at atmospheric pressure and a current of 3.5 A. A combination of spatially resolved synchronized optical emission spectroscopy and laser absorption spectroscopy methods was used to diagnose plasma parameters. The radial distributions of the excitation temperature and the number densities of copper and molybdenum atoms were determined using the Boltzmann plot technique. Based on the experimentally determined plasma parameters, the equilibrium plasma composition was calculated taking into account the dissociation and ionization products of oxide additives, in particular stable monoxides YO and AlO.
Dielectric behaviour of g3 or CO2/O2 mixtures after current interruption have been studied by numerical model. Arc properties during the arcing phase were determined from two-dimensional axisymmetric time-dependent magneto-hydrodynamic simulations. The probability of arc re-ignition (breakdown) after current interruption have been then estimated from evaluation of streamer criterion for the whole calculation domain. Corresponding input data - critical electric fields and effective ionisation coefficients - have been determined from the solution of kinetic Boltzmann equation for the electrons.
For several years now, the gradual electrification of aircraft has been one of the levers for the transition in the aeronautical field. Of course, the all-electric aircraft remains a prospect that does not apply to commercial aviation, but the more electric aircraft, and even hybridisation, seem to constitute concrete developments. Under these conditions, an increase in the electrical power of on-board grids seems inevitable. Future voltages are likely to be +/- 270 VDC or more. Such a change entails new constraints, including the need to switch off DC grids at such voltages and, moreover, at sub-atmospheric pressures. In this article, we present experimental work concerning the opening (at DC voltage) of a contact under aeronautical pressure conditions. The experimental conditions are as follows: pressure is between 200 hPa and 1000 hPa, supply voltage is 540 VDC, and the current when the contact is closed is 50 A. The change in contact voltage and current are measured. The influence of pressure on these signals and on the arc structure observed in fast cinematography is presented.
Ultra-fast opening mechanical switches are proposed as key components for medium-voltage DC circuit breakers, enabling rapid fault current commutation to a parallel capacitor. After arc extinction in the commutating switch, the gas-filled gap is exposed to rapidly rising transient voltages, and the success of commutation depends on fast dielectric recovery. This paper presents a method to estimate the arc temperature at the time of arc extinction and its subsequent decay after full current interruption in a fast-elongating arc with short arcing times. A modified Lowke model, accounting for arc thermal inertia, is used to track the evolution of arc temperature and radius from arc initiation up to arc extinction. Post-extinction gas temperature decay is modeled using heat transfer in a simplified cylindrical geometry. Finally, the dielectric breakdown voltage of the gap is estimated via critical field theory, accounting for temperature-dependent breakdown fields.
To meet the decarbonization objectives set forth by the European Union, the aerospace sector is engaged in the development of a novel category of regional hybrid aircraft that integrates advanced DC technologies alongside conventional systems. This publication presents the proposed direct current (DC) system of the next-generation hybrid aircraft focusing on one of the protection elements developed for the kilo-volt DC (KHVDC) network, namely a mechanical contactor. The contactor design, its key characteristics as well as the chosen numerical model are presented and discussed in detail. The magnetohydrodynamics (MHD) model, details and focuses on a solution that integrates two distinct Ansys software packages, Fluent and Electronics Desktop (Maxwell 3D), chosen to enhance the electric arc modeling in non-linear magnetic environments. The qualitative results obtained from the numerical model will be discussed against experimental observations.
The effect of driving dual frequencies in a separate-Electrode dual-frequency capacitively coupled argon plasma discharge is investigated using a Particle-in-Cell with Monte Carlo Collisions (PIC-MCC) model. The frequency (13.56 MHz) is applied on one electrode, while the opposite electrode is powered by a variable frequency ranging from 27.12 MHz to 67.8 MHz. Our numerical results demonstrate that the combined electrical and geometric asymmetry effects enable quasi-independent control of ion bombardment energies at each electrode. Specifically, increasing the high frequency on the large-area electrode leads to a marked rise in the ion energy at the opposite, low-frequency powered small electrode, even as the DC self-bias voltage decreases. Furthermore, we find that the high-frequency powered electrode consistently sustains the highest ion energies, irrespective of its surface area.
Accurate high-voltage arc simulation is vital for optimizing circuit breakers, critical for power grid protection. Complex arc phenomena, especially radiative heat transfer, pose significant computational challenges. This paper validates the Equal Emission Banding (EEB) method for efficient radiation transfer in switching arcs. The method balances accuracy and computational time, improving precision without significant overhead. This advancement is expected to aid future research.
The ozone destruction at higher gas temperatures was studied in a quartz cuvette. The cuvette was heated by a resistance wire wound on the outer surface of the cuvette. The cuvette was filled with ozone and the time dependence of ozone concentration in the cuvette was measured by absorption spectroscopy. The rate constant for ozone decay was derived from this time dependence. The influence of the rate constant on surface condition (the surface concentration of adsorbed oxygen atoms and molecules) was studied. The surface concentration of adsorbed oxygen atoms was changed by reactions with gaseous molecular oxygen just before the cuvette was filled by ozone. The cuvette temperature was set to 40, 50 and 60 ◦C. The measured rate constants increase with increasing temperature from the value 1.27 × 10−4 s−1 to 1.88 × 10−4 s−1. The influence of temperature and cuvette surface coverage on ozone decay constants is discussed.
We present a three-dimensional (3D) Magneto Hydrodynamic Model (MHD) at two temperatures (electronic and ionic) of inter-electrodes plasma, simulated with Ansys Fluent coupled with specific developments in C language. The stationary model describes a subsonic arc in vacuum at 15 kA between copper contacts, submitted to an Axial Magnetic Field (AMF). Due to high temperatures, losses by radiation need to be considered. Even if departures from Local Thermal Equilibrium (LTE) exist, currently due to lack of appropriate data, net emission coefficient data calculated under LTE are used and attributed exclusively to electron energy equation. Two cases are investigated in this study, with or without considering the radiation in the electrons energy equation. The study highlights the importance of better characterizing radiative losses in order to improve the reliability of numerical models.
Proposed hybrid DC circuit breaker concepts rely on the arc voltage in vacuum interrupters to commutate fault currents to parallel branches. This paper presents an extensive experimental investigation of the diffuse vacuum arc voltage of an industrially manufactured vacuum interrupter which is connected to a Thomson coil actuator. By independently varying the opening speed and arc current, an empirical model describing the diffuse vacuum arc voltage as a function of contact distance and current is derived. The model limits are evaluated by discussing the transition phase towards high-current anode mode formation.
Arc conductance decay is a well-established performance indicator for thermal interruption in SF6, with a narrow range of known limit values. It is also shown that conductance decay can also serve as a performance indicator in CO2-based mixtures, although different limit values for successful thermal interruption apply. In this publication, values of arc conductance 200 ns before current zero are presented for a large number of experiments performed in CO2/O2 90/10 mixture under short line fault-like conditions. These measurements are used to establish limit values for the CO2/O2 mixture, and to investigate the pressure dependence of conductance decay.
Synthetic testing has been extensively utilized to study the thermal interruption performance of CO2-based gas mixtures under the influence of varying physical factors in an experimental HV circuit breaker. To limit contact and nozzle ablation for collecting a statistically meaningful dataset, the lowest possible peak current amplitudes were chosen for the high-current and the injection current phases. The present work focuses on evaluating the sensitivity of the test-circuit parameters on the interruption performance in CO2/O2 (90% /10%) gas mixture.
With the rapid development of Renewable energy, DC power system, Energy Storage System and Rail Transit etc, the demand of high performance Direct Current circuit breakers is increasing significantly. Gassing materials can improve the interruption capability during the arc ignition process, however, the decomposition process and reaction products will be affected by the onsite environment, such as pressure, oxygen concentration and humidity. Using molecular dynamics simulations, the decomposition process of PA66 under an electric field at varying oxygen contents was analyzed. The results show that the introduction of oxygen accelerates the decomposition of PA66, not only promoting hydrogen generation but also suppressing the formation of tar and coke, and provides a preliminary standard for choosing the qualified gassing materials.
This paper proposes a magnetohydrodynamic arc model for direct current arc interruption simulation in a low-voltage switch with a contact bridge design. Arc voltage and current for the interruption of an initial current and voltage in the 800 V and 800 A range are compared and differences discussed between the simulation and an experiment. The arc is successfully quenched in the simulation, but discrepancies between simulation and experiment may be attributable to erosion modeling.
This study examines the effects of arc-induced ageing in CO2/O2 (86.3%/13.7%),C4F7N/CO2/O2 (5%/82%/13%) and C4F7N/CO2 (5%/95%) mixtures at 5 bar absolute pressure. The gases were subjected to a series of free-burning arcs with a total energy dissipation relevant to high-voltage circuit breaker applications. The arc voltage remained similar across all mixtures with no significant variation due to ageing or the addition of C4F7N and O2. In addition, the influence of the insulating gas on the erosion of the arcing contacts (20% wt. Cu/80% wt. W) was analyzed. While the increase in average surface roughness was comparable across all mixtures, the contact mass loss was relatively higher in those containing C4F7N. Decomposition of the gas mixtures was examined through gas chromatography-mass spectrometry analyses. Solid byproducts generated during arcing were analyzed using scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS).
The technologies of spark gaps involve two distinct types of current: an impulse current that simulates a lightning strike and a follow current resulting from the persistence of the arc after the impulse. This study shows the behavior of the electric arc with 8/20 µs impulse current followed by a 200 A follow current, using both experiments and numerical tools. The geometry includes a pre-chamber, a main chamber (without separators), and an open outlet. We developed a three-dimensional (3D) numerical model to simulate the arc movement. This model is based on the assumption of local thermodynamic equilibrium (LTE) and operates under unsteady conditions. In our experiments, we use high-speed camera recordings and electrical measurements. A good agreement is observed between the numerical model and the experimental measurements, both in terms of arc shape and arc voltage values.
This work presents the development of a MagnetoHydroDynamic (MHD) model to simulate electric arc behavior in a low-voltage circuit breaker chamber. The modeling process began with a simplified geometry to validate key phenomena such as arc displacement, segmentation, and voltage rise, showing good agreement with literature. To approach realistic conditions, contact rotation was implemented using a layering technique, improving numerical accuracy and avoiding mesh deformation.A current-limiting mechanism and electrical network coupling were also introduced, enabling dynamic current input. These modules were integrated into a 3D geometry representing a real chamber, successfully reproducing arc evolution under realistic conditions. The model captures complex arc physics and helps in future design optimization of low-voltage devices.
In previous studies of plasma spraying, a plasma jet was considered as a constant background in which particles are fed to be heated, molten and deposited on a target. This assumption is well justified for low feeding rates. At high rates, the particles can affect the plasma jet. This effect is studied here in terms of a bidirectional interaction between the plasma jet and the injected particles. The influence on the jet temperature and velocity in the plume, and the resulting coating is analysed.
This work describes the use of experimental methods on model spark gaps for comparison with the simulation models (MHD) from the ignition of the impulse arc to the entry of the arc into the arc chamber, taking into account material effects and thermal reignitions of the arc, e.g. as a result of the gas flow within the encapsulated spark gap. Examples are provided to show that the simulation can accurately represent the experimental processes and improve the understanding of the complex processes.
This paper presents a one-dimensional simulation of the dielectric barrier discharge (DBD) in pure methane under atmospheric pressure. By employing a fluid model integrated with a set of plasma chemistry to analyze discharge behavior, we study different plasma characteristics, including applied voltage, discharge current, electron and ion density, and diverse chemical species density. Additionally, the study investigates the influences of the variation of applied voltage and the insulation layer constant on the characteristics of the DBD reactor and methane conversion. The findings reveal that increasing the applied voltage and dielectric constant influences the discharge behavior, enhancing methane dissociation.
