PLASMA PHYSICS AND TECHNOLOGY

Multiphysical Simulation of Impulse Current Arcs in Spark Gaps for Industrial Applications

2023-08-21T15:11:11+02:00

Digital prototyping enables cost-effective production and modular optimization of surge protection devices (SPD). Numerical model of SPD prototypes involves complex multiphysics phenomena. However, the processes related to impulse current arcs in spark gaps are not well understood so far. Limited knowledge exists regarding hydrodynamic effects, plasma states, and radiation properties. This work studies an impulse current 8/20 µs with an amplitude of about 5 kA in experiment and simulation.

Influence of Gas Temperature on Gaseous Products Generated by Coplanar Barrier Discharge in Air and N2/O2 Mixtures

2023-08-08T10:03:27+02:00

Absolute densities of gaseous products generated by coplanar dielectric barrier discharge in N₂/O₂ mixtures and in ambient air were determined by UV optical absorption spectroscopy (OAS). Ozone (O₃) and nitrogen oxides (N₂O, NO₂ and N₂O₅) were identified as the stable products of the discharge. It was found that the actual product composition strongly depends on the gas temperature. At low input power with the low gas temperature, O₃ density was high and the NO₂ density was very low. When the input power increased and the gas temperature also increased, then O₃ disappeared, while NO₂ density started to increase steeply.

Characterization of Ultrahigh Pressure Nitrogen Arc Using Black Box Arc Model

2023-08-03T20:40:40+02:00

In this paper, the effect of filling pressure on the black box arc parameters of nitrogen arc is reported using Mayr arc model. The arc current is approximately 130 A at 190 Hz. The filling pressure is varied at absolute pressure of 1, 20, and 40 bar. A phase transition from gas to supercritical state occurs when the pressure of nitrogen exceeds 33.5 bar at room temperature. To determine the effect of forced cooling, first, the free-burning arc is studied at different filling pressures. Afterwards, a self-blast arrangement is used where gas is blown into the arc near current zero. It has been observed that, without forced gas flow, both the time constant and the cooling power of the arc increase with the filling pressure. The forced cooling, however, reduces the time constant and further enhances the cooling power, thus facilitating the current interruption.

Plasma Properties of Electric Arc Discharge Burning Between Cu-W Composites Electrodes

2023-08-17T16:46:56+02:00

Plasma of electric arc discharge burning between different types of composite Cu-W electrodes was investigated. Electrodes manufactured of Cu-W composite materials (30/70% by mass) by shock sintering technology at temperatures of 750, 850, 950, and 1050°C were used. Optical emission spectroscopy techniques were applied to determine the main plasma parameters. Specifically, the side-on spectra of plasma emission were registered using a space-resolved spectrograph with a CMOS camera as a sensor device. The plasma thermodynamics properties were calculated based on the equilibrium plasma composition, which was determined using experimentally obtained radial distributions of temperatures and atom concentrations of the metals.

The Effect of Gas Type on Flow Characteristics in a Circuit Breaker under Cold Flow Scenario

2023-08-11T22:26:32+02:00

This paper presents first stage of supersonic flow modelling in gas circuit breakers without an arc. Flow characterisation focused on shock and flow separation phenomenon. Velocity deceleration caused by shock will play a significant role in determining arc cooling performance and will impact thermal interruption capability. Gas properties such as specific heat ratio, density, and viscosity influenced the flow characteristics including shock location, strength and the flow separation process.

Two-dimensional Axisymmetric Modeling of the Magnetic Field for High-voltage Gas Circuit Breakers

2023-07-27T13:02:41+02:00

High fidelity numerical analyses of high-voltage gas circuit breakers have been conducted at Hitachi Energy Research with an in-house CFD-based arc simulation tool. The tool extends the capability of a commercial flow solver (ANSYS Fluent) to represent physical phenomena at play in a high voltage circuit breaker during a breaking operation, such as magnetostatics, polymeric and metal evaporation, and arc-network interaction. This work describes the implementation of the Biot-Savart law for computing the magnetic field generated by an electric arc under the magnetostatic approximation and in two--dimensional axisymmetric conditions. The implementation is compared to the reference one based on the magnetic vector potential formulation of the Amp`ere’s law in the Coulomb gauge. The limitations of the two formulations are discussed and their numerical accuracy compared.

Molecular Dynamic Simulation of the Effect of Initial Surface Temperature on Arc Erosion Due to Ion Bombardment

2023-09-01T18:48:50+02:00

This study focuses on the effects of initial surface temperature on arc erosion caused by ion bombardment. The simulation results show that higher surface temperature leads to a greater number of lost Cu atoms and an increased size of the erosion crater. This is due to the ability of the incident ions to have a greater sputtering yield at higher temperatures. Moreover, the Cu atoms tend to agglomerate and form clusters after ion bombardment while leaving the surface.

Electrical Erosion Resistance of Graphene Reinforced Cu-W Circuit Breaker Contact Materials under 5 kA Arc

2023-08-21T15:04:46+02:00

This work integrates experimental and MD simulation approaches to study the role of graphene in G-Cu-W composites. Arcing tests were conducted on G-Cu-W and Cu-W contact samples under a 5kA peak current. Experimental results show that adding graphene leads to a lower surface roughness of the sample following arcing. MD simulation results indicate that the G-Cu-W model exhibits a smoother surface and fewer lost metal atoms than the Cu-W model due to the protective effect of graphene layer.

Optical Investigation of a Spark Gap for DC Protection around Current Zero

2023-09-21T22:07:59+02:00

The applied experimental setup consists of a pair of fixed electrodes forming a short gap in air. The electrodes are connected with a thyristor forming a parallel current path. Once the thought flashover ignited arc has burnt a given time in the range of several hundreds of microseconds, the thyristor will be fired causing a commutation of the current in the semiconductor path. Hence, the current through the electrode gap will be reduced. The extinguishment of the arc permits the creation of a current zero in the gap. The focus of the experimental work is set to the analysis of the arc plasma during the DC phase and its distinction in the current extinction phase (current zero). High speed camera observation and optical emission spectroscopy are carried out and combined with the electrical measurements.

A Pressure Based Compressible Solver for Electric Arc-plasma Simulation

2023-08-28T17:13:30+02:00

The electric arc discharge in a liquid medium is used in several applications such as the sterilization of the liquid by UV radiation, the fracturing of rocks by shock wave, the circuit breakers in oil bath or the forming of mechanical parts. Thus, describing the physics of the arc in a liquid and in particular its interaction with a liquid interface is an important issue to better characterize this type of configuration. However, such a challenging task requires to couple high-fidelity solver for compressible two-phase flows with liquid phase change and a plasma solver to describe the plasma and its interaction with the bubble. To study this type of medium, we use a compressible formulation of the fluid equations. For this purpose, a pressure based solver has been developed for the computation of the energy conservation equation. Moreover, our numerical model uses the immersed boundary method to simulate the solid electrodes. The numerical model is briefly described in this paper and the first results of the electric arc discharge in steam water are presented. To our knowledge this pressure based model has never been used to describe plasmas and electric arc discharge.