Arc Voltage Research Articles

Analysis of transient recovery voltage and secondary arc current in transposed extra-high voltage lines in a two-phase auto-reclosing

Extra-high voltage (EHV) lines of 500–750 kV, providing transmission of electricity over long distances and at the same time performing the functions of intersystem communication at the level of the national power system, play an important role not only in normal modes, but also in emergency modes, ensuring the dynamic stability of the power system as a whole. In these lines, the overwhelming proportion of power cuts are caused by single-phase short circuits (90%), a significant part of which, being unstable arc faults, are successfully eliminated in the single-phase auto-reclosing cycle. Also, about 5%–10% of failures can be constituted by two-phase short circuits, which can be eliminated in a two-phase auto-reclosing cycle (TPhAR). The purpose of this paper is to study two-phase auto-reclosing in transposed EHV lines equipped with four-radial shunt reactors (ShR). The paper analyzes the efficiency of using a two-phase auto-reclosing to eliminate two-phase short-circuits in the lines connecting the power systems of Kyrgyzstan and Tajikistan. An algorithm is proposed for calculating the transient recovering voltages (TRV) and secondary arc currents (SAC) in the real transposed line Datka–Khujand–Dushanbe. The obtained results of TRV and SAC, which are within the permissible limits for the Dushanbe–Khujand line section, make it possible to have a dead time of TPhAR of no more than 0.6 s, in order to maintain the dynamic stability of the power system. For lines with a length of about 500 km (Datka–Khujand), equipped with three reactors, a successful TPhAR is impossible due to the appearance of resonant TRV in the circuit. The paper proposes the use of banks of capacitors connected in series in the phases of the ShR for the implementation of a successful TPhAR with the duration of the required pause of about 0.6 s.

Detection of Arcing and High Impedance with Electrical Weapons.

Conducted electrical weapons are primarily designed to stop subjects from endangering themselves or others by deploying 2, or more, probes to conduct current via the body to induce motor-nerve mediated muscle contractions, but probe impedance can vary significantly including open circuits from probes failing to complete or maintain a circuit. We tested 10 units of the TASER® 7 model with a range of impedances and open circuit conditions. Pulse data (stored in the device's memory) were used to predict the load resistances and detect arcing conditions. Acoustical data (recorded externally) was evaluated on an exploratory basis as a secondary goal. The average error of predicted resistance, over the physiological load range of 400-1000 Ω, was 8%. Arcing conditions was predicted with an accuracy of 97%. An arcing condition increases the duration of the sound generation. The TASER 7 electronic control device stored pulse-log data for charge and arc voltage yielded forensic analysis of the load resistance with reliable accuracy.

Modeling and Estimation of Break Arc Extinction Distance in Low Voltage DC Systems

Recently, as DC power generation and DC loads such as renewable energy and EVs increase, the need for a low-voltage direct current (LVDC) distribution system has gradually emerged. The DC system has various advantages, such as system stability, transmission efficiency, and connectivity to renewable power generation compared to AC distribution systems. One of the important technical issues for commercialization of DC distribution system is safety. Since the DC system does not have a current zero point, unlike the AC system, a breaking arc accompanied by a high-temperature plasma is easily generated when the circuit is cut off. The arc can cause fire accidents that threaten people and facilities. In order to prevent customers and facilities from the accidents caused by the arc in the DC system, a study on the characteristics of the DC breaking arc is necessary. An important factor of characteristics for the DC breaking arc fault is an arc extinction distance at which the DC breaking arc is completely extinguished. There are two major behaviors in DC breaking arc; one is active behavior where the arc voltage is inversely related with the arc current for a given gap distance, the other is passive behavior where the arc voltage is negatively proportional to the arc current according to Kirchhoff’s voltage rule. This paper combines the two arc characteristics together to establish a DC breaking arc model, and proposes a method to estimate the arc extinction distance. Experiment results verify the method under various power and load conditions.

A defect detection system for wire arc additive manufacturing using incremental learning

In more recent times, research on various aspects of the Wire Arc Additive Manufacturing (WAAM) process has been conducted, and efforts into monitoring the WAAM process for defect identification have increased. Rapid and reliable monitoring of the WAAM process is a key development for the technology as a whole, as it will enable components produced by the process to be qualified to relevant standards and hence be deemed fit for use in applications such as those found in the aerospace or naval sectors. Intelligent algorithms provide inbuilt advantages in processing and analysing data, especially for the large data sets generated during the long manufacturing cycles. Interdisciplinary engineering (IDE) furnishes a concept integrating computer science and industrial system manufacturing engineering together to treat large amounts of process monitoring data. In this work, a WAAM process monitoring and defect detection system integrating intelligent algorithms is presented. The system monitors welding arc current and voltage signals produced by the WAAM process and makes use of a support vector machine (SVM) learning method to identify disturbances to the welding signal which indicate the presence of potential defects. The incremental machine learning models developed in this work are trained via statistical feature analysis of the welding signals and a novel quality metric that improves detection rates is also presented. The incremental learning approach provides an efficient means of detecting welding-based defects, as it does not require large quantities of data to be trained to an operational level (addressing a major drawback of other machine learning methods). A case study is presented to validate the developed system, results show that it was able to detect a set of defects with a success rate greater than 90% F1-score.

Enhancement of Imperfection Detection Capabilities in TIG Welding of the Infrared Monitoring System

For a low cost, there are industrial infrared monitoring systems used for imperfection detection and identification in welded joints. The key drawback that impedes real life industrial applications is the low spatial resolution, as well as the temporal resolution of low-cost infrared (IR) cameras. This is also the case in tungsten inert gas (TIG) welding. Taking into consideration the influence of voltage on the arc energy and heat input, high frequency sampled voltage was used to evaluate the interpolated temporal resolution of IR sequences. Additionally, a reflected temperature correction method was proposed to reduce the uncertainty of absolute temperature measurement with a thermographic camera. The proposed method was applied to detect several imperfection types, such as lack of or incomplete penetration as well as incorrect weld shape and size (including burnouts). Results obtained for different interpolation factors were compared. The obtained results emphasize the validity of reflected temperature correction method. For the weld defects detection task, the smallest detectable defect was found for various interpolation factors. Moreover, the correspondence of arc voltage and the joint temperature was checked. Additionally, a set of decision rules was elaborated on and applied to distinguish between various joint conditions. It was found that defects that do not have symmetrical temperature distribution with respect to the joint axis are harder to identify.

The effect of substrate and arc voltage on the structure and functional behaviour of NiTi shape memory alloy produced by wire arc additive manufacturing

This paper aimed to study the influence of the substrate and the arc voltage on the structure and functional properties of the NiTi shape memory alloy produced by wire arc additive manufacturing (WAAM). The gas metal arc based WAAM process was used for the deposition of 3-layered NiTi walls on a titanium or steel substrate at different arc voltages using a Ni 50.9 Ti 49.1 wire. It was found that in the sample deposited on the Ti substrate, the Ti 2 Ni phase appeared and the Ti concentration in the NiTi phase increased to 50.5 at.%. An increase in the arc voltage influenced the volume fraction of Ti 2 Ni precipitates in the 1st layer but hardly affected the chemical composition of the NiTi phase in all layers as a result, the martensitic transformation temperatures do not depend on the arc voltage. Therefore, the deposition of the Ni-rich NiTi wire on a Ti substrate allowed for the production of the Ti-rich NiTi walls undergoing the martensitic transformation and demonstrated the shape memory behaviour at high temperatures. An increase in the arc voltage hardly affected the shape memory behaviour but decreased the strain up to failure due to an increase in the volume fraction of the brittle Ti 2 Ni phase, which in turn facilitated the formation of cracks during deformation. In the sample deposited on the steel substrate, the NiTiFe solid solution and Ti-C, Ni 3 Ti 4 , and Ni 3 Ti 2 precipitates formed in the 1st layer. An increase in the arc voltage led to an increase in the Fe concentration in the NiTiFe solid solution from 17 at.% to 42 at.% in the 1st layer. From layer to layer, the Fe concentration decreased; however, it remained larger than 1.5 at.% and completely suppressed the martensitic transformation and the shape memory effects in the NiTi sample deposited on the steel substrate.

Analysis and Tests of the Impact of Permanent Magnets on Current Interruption in a Medium Voltage Rotary Load Break Switch

Abstract The breaking capacity of a medium voltage (MV) rotary SF6 load break switch (LBS) can be improved by incorporating permanent magnets into the stationary contacts. The magnetic field is intended to blow the switching arc root towards a recessed space at the stationary contacts thereby preventing reignition of the arc after current zero. Making and breaking tests of load current 630 A were performed comparing the switching performance of load break switches equipped without a permanent magnet, with a ferrite and with a neodymium magnet. The impact of different polarity arrangements of the magnets in the three phases is also considered and analysed. In order to understand the arc behaviour caused by the effect of permanent magnet, arcing times and arc voltage were measured and evaluated. The results show that the arc voltage depends on the direction of the electromagnetic force, which is determined by the phase current direction but also by the polarity of the magnets. When the force is directed towards the recessed space at the stationary contacts, the arc voltage is notably higher than in the case where the arc is blown in the opposite direction. The higher arc voltage is a reliable indication that the length of the arc is increased, which significantly reduces the risk of both thermal and dielectric breakdowns after the first current zero. The consequences are noticed first in the reduction of the number of missed current zeroes and second in shorter minimum arcing times. An adverse arrangement of the magnet polarity in the three phases increases the number of missed current zeroes.

Effect of Flow Rate on the Characteristics of Atmospheric-Pressure AC Constant-Current Powered Gliding Arc Discharge

In this article, a nonthermal gliding arc discharge (GAD) was generated in an air flow driven by a 40-kHz alternating current (ac) constant-current electric power supply. The influence of gas flow rate on the discharge characteristics of gliding arc was investigated using electrical diagnostics and fast Fourier transform (FFT) analysis method. The average discharge power, total harmonic distortion rate of arc voltage (THD <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${_{u}}$ </tex-math></inline-formula> ), total harmonic distortion rate of arc current (THD <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${_{i}}$ </tex-math></inline-formula> ), and the resistance of arc were experimentally studied. As the air flow rate increased from 4 to 12 L/min, it was found that the average discharge power of the gliding arc gradually decreased from 407.9 to 187.8 W. However, because of the nonlinear characteristics of the GAD circuit, with air flow rate increasing, both THD <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>u</i></sub> and THD <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>i</i></sub> linearly increased, while the resistance of arc gradually decreased from 26.3 to 14.1 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{k}\Omega $ </tex-math></inline-formula> . Totally, the air flow rate influenced the discharge characteristics of the gliding arc mainly by ruling the average discharge power. Finally, for a better understanding of the discharge characteristics of the gliding arc, a discharge circuit model was further analyzed based on the average discharge power and reactive power.

Simulation of wire and arc additive manufacturing of 308L stainless steel with cold arc gas metal arc welding

This research focuses on the capabilities of coldArc GMAW in the behavior of heat input to the weld bead dimension. In this study, the effect of process GMAW of 308L stainless steel filler wire with a thickness of 1.2 mm and 304L stainless steel base plate, with a dimension of 120 mm x 25 mm x 10 mm (height x width x thickness) by applying WAAM. The data was collected using MATLAB of a Smart Weld Rosenthal’s Steady-State 3D Isotherms. A Taguchi response was used in the DOE method with Minitab software to analyze the effect of process parameters on height, width, and depth of weld bead dimension during GMAW. The experiments were conducted following the low, mid, and high input parameters will show the different structures of weld bead dimension, which include 70 A, 75 A, and 78 A (arc current), 15 V, 16 V, and 17 V (voltage), 400 mm/min, 600 mm/min, and 800 mm/min (welding speed). Hence, the optimum value is 75 A, 16 V, and 800 mm/min, and the most significant parameters to deposit stainless steel with coldArc GMAW were welding speed followed by arc current and voltage.

Study on Real-Time Porosity Defect Detection Through Neural Network Structure Optimization using Genetic Algorithm in GMAW

Zinc-coated steel sheets are widely applied as automotive chassis parts because they have high corrosion resistance and good compatibility. However, in the gas metal arc welding (GMAW) process, serious porosity defects occur due to zinc vapor generated during welding, which causes problems such as durability or productivity reduction in the welded structure. To secure weldability and productivity, it is essential to secure monitoring technology that determines whether porosity defects are generated in real-time. To solve this problem, this study provides a method of extracting feature variables from arc voltage signals generated during welding and optimizing the hyper parameters of the porosity detection algorithm deep neural network (DNN) which be learned with feature variables by applying genetic algorithm (GA). To verify the performance of the proposed method, as a result of applying it to the optimized DNN model using the experimental data of the GMAW experiment using a high-strength zinc-coated steel sheet, a prediction accuracy of 93.1 % was derived, which is improved by 3.60 % than DNN model from previous research.

NASA Air Force Spacecraft Charging Analyzer Program Confirmation of GPS Arcing

GPS satellites undergo surface contamination on the solar array coverglasses from repeated arcing events. Using NASA Air Force Spacecraft Charging Analyzer Program (Nascap-2 K) spacecraft charging simulation software, a GPS Block IIF satellite model was constructed and analyzed in realistic Medium Earth Orbit environments. GPS Block IIF satellites have Qioptiq CMG-type coverglasses (as do all other GPS satellites). The Nascap-2 K model with CMG coverglasses charges to high differential levels in maximum charging environments, in the range above the arcing threshold, as determined by studies at the Air Force Research Laboratory (AFRL), and so arcing is confirmed by theory. This finding agrees with onboard Los Alamos National Laboratory measurements and Arecibo observational data for GPS satellites. Other AFRL results show that CMX-type coverglasses, being more bulk-conductive, should charge less and perhaps mitigate arcing on the solar arrays. A Nascap-2 K model using CMX coverglasses is shown to charge differentially much less than CMG, and not reach levels above the arcing threshold. In the simulation, the commonly used CMG coverglass charges quickly, exceeding its arcing voltage threshold of 1500 V in about 1 h and 10 min. In comparison, CMX results indicate an ability to remain well under its arcing threshold throughout the orbit.

Experimental Study of Arc Motion Near Splitter Plates in Low-Voltage Switching Devices

Switching performance of a low-voltage switching device (LVSD) is determined by limiting current and stopping re-ignition. This is strongly influenced by how the arc moves inside the LVSD quenching chamber during the switching process. Improved switching performance is achieved when the arc quickly enters and stays inside the splitter plates of the LVSD, with the arc attached to the surface of the plates. This article studies arc motion around splitter plates in LVSDs and the correlation with arc voltage. Arc motion is investigated using a high-speed optical arc imaging system (AIS). It is observed that the arc fluctuates as it enters the splitter plates, with periods inside the plates followed by sudden re-strikes of the arc roots outside the plates. The AIS system allows the measurement of arc displacement and a correlation with the arc voltage. The results show two phases, with a narrow correlation while the arc in the chamber out of the splitter plates and a distributed correlation while in the splitter plates. Further, a new performance parameter the splitter time (ST) ratio is defined. The influence of the ST ratio on the chamber vent design is investigated. It is found that with wider and well-distributed vent apertures, the ST ratio is higher than with a closed vent, and arc motion on entry to the plates is improved.

Arc extinction with nitrogen at 1-40 bar in a puffer-like contact configuration

To develop cost-efficient subsea switchgear for large sea depths, the extinction of arcs under high filling pressures must be understood. In this work, arc-extinction experiments have been performed with a puffer-like contact configuration using nitrogen at different filling pressures as the current interruption medium. The main finding is that, for the given contact configuration, the currentinterruption capability was lower at 20 and 40 barabs than at 1 and 10 barabs. While higher pressures result in higher cooling flow rates and longer flow times given the same puffer volume, compression spring and nozzle geometry; it does not necessarily improve the arc-extinction capability. This is probably because higher filling pressures increase the arc voltage and total energy dissipated in the arcing zone. Because the filling pressure greatly influences the flow characteristics, the puffer design should be optimized for each pressure level.

Study of Vacuum Arc Rotation Characteristics of Different Transverse Magnetic Field Contacts

As a special phenomenon under transverse magnetic field (TMF) contacts, vacuum arc rotation deserves more attention. In this article, rotation characteristics of three typical TMF contacts, i.e., swastika-type, cup-shaped, and double-TMF contacts, are systematically studied. According to arc images, recorded by a high-speed camera, physical terms related to arc rotation such as rotation duration and rotation speed are clearly defined. The magnetic field and Lorentz force are calculated and the force balance of the moving arc is analyzed. On this basis, the effects of arc ignition mode, peak current, and contact type on arc rotation are investigated. Arc voltage noise as well as arc splashing outside caused by rotation is also discussed. The results show that the duration from ignition to rotation in two-point arc ignition (TPAI) mode is usually the shortest because of the rapidest constructed column formation. As the peak current increases, arc rotation becomes easier. Due to stronger TMF, the arc under double-TMF contacts has the longest rotation duration and the highest rotation speed.

Low current arc ignition stability in micro-TIG welding

Micro‑tungsten inert gas (TIG) welding is widely used in electronic component manufacturing. Arc ignition under low current should be employed to avoid burning the micro-component. However, it is relatively complex to manipulate. To improve the stability and reliability of the arc ignition under low current, the effect of the ignition method, cathode spot motion (CSM), and welding circuit inductance is investigated. High voltage arc ignition (HVAI) experiments are carried out with different inductances under various CSM amplitudes. A high-speed digital camera is employed to record the arc image, while a digital oscilloscope is used to simultaneously detect the arc voltage and current waveforms. The results show that HVAI can achieve smooth arc ignition with the low current in a relatively long discharge gap. The inductance in the welding circuit plays an effective role in maintaining the burning of the micro-arc. However, overly high inductance prevents arc formation just after the breakdown of the gap. When a traditional TIG welding torch is used, cathode spots move violently at the beginning of the low current arc ignition. This results in arc oscillation in the space or even rapid extinguishing. By placing an insulating ceramic tube on the tungsten electrode, the emission of electrons can be limited to the electrode tip. This, in turn, restricts the range of motion of the cathode spots to the tip region. Consequently, low-current arc ignition performance is improved.

Non-equilibrium modeling on the plasma–electrode interaction in an argon DC plasma torch

A 2D two-temperature chemical non-equilibrium model considering both cathode and anode space-charge sheath is applied to investigate the plasma–electrode interaction in a laminar argon DC plasma torch working at atmospheric pressure. In order to validate the model, the predicted arc voltage is compared with experimental values under different working conditions, and a reasonable agreement is obtained. The distributions of arc characteristics in the plasma column and electrode regions of a DC arc plasma torch are analyzed in detail. Moreover, the effects of thoriated tungsten, pure tungsten and non-uniform thoriated tungsten cathodes on the plasma characteristics inside the DC plasma torch are investigated. It is found that a constricted arc attachment with the highest current density is obtained at the non-uniform cathode, leading to the largest velocity and electric potential drop in the plasma column. The pure tungsten cathode produces the highest temperatures and heat flux along the cathode surface, which is caused by the largest arc voltage and intense space-charge sheath heating. The temperature and heat flux density on the thoriated tungsten cathode are the lowest, leading to a diffuse distribution of current density. The results indicate that the different cathodes can exert an important influence upon the plasma behavior near the cathode. Furthermore, the torch exit parameters are also slightly different due to their different arc voltages and overall input power.

DEVELOPMENT OF TECHNOLOGY AND CREATION OF TEST EQUIPMENT FOR PRESSURE WELDING OF HIGH-LOAD THIN-WALLED HETEROGENEOUS STEEL TUBULAR PARTS

Introduction. Magnetically impelled arc butt welding (MIAB) method differs from the existing arc methods by high productivity, stable quality of welded joints, high degree of mechanization and automation of the technological process and so on. Welding is performed automatically, which significantly reduces the influence of theoperator-welder on the quality of welded joints. The optimal values of the magnetic field induction components for thin-walled tubular parts with a diameter of 212 mm are determined. The basic technological parameters on welding of tubular details in stationary conditions are defined, it is: qualitative preparation of end faces of pipes;optimal distribution of induction of the control magnetic field (CMF); arc voltage; the magnitude and order of programming the welding current; the rate of closure of the arc gap in the process of upset. The influence of liquid metal melt in the arc gap during upset on the formation of welded joints of pipes is determined. Metallographicstudies showed no defects in the weld line and a relatively small area of thermal impact. Mechanical properties of welded joints at the level of mechanical properties of the base metal. Studies have been conducted to determine theparameters that affect the stable movement of the arc along the thin-walled edges of tubular parts and the influence of liquid metal melt in the arc gap during heating on the formation of welded joints.Problem Statement. Pipes of small diameters (up to 220 mm) are used in various industrial enterprises and construction of pipelines. The work requires high-performance automatic welding methods that allow obtaining stable and reliable welded joints.Purpose. The purpose is to raise labor productivity and to save materials by using equipment and technology for press welding of magnetically controlled arc of thin-walled tubular parts.Materials and Methods. Steel thin-walled tubular parts with a diameter of 42mm and 212 mm, with a wall thickness of 2.5… 3 mm were used for research on press welding. To create a control magnetic field, magnetic systems for tubular parts with a diameter of 212 mm were developed. Experimental welding was performed andsamples of welded joints of pipes with a diameter of 212 mm with a wall thickness of 3 mm were investigated. In the course of the research, the main parameters are recorded and the welding process is controlled by computer. Results. The main technological parameters: preparation of pipe ends; magnitude and distribution of control magnetic field induction; the arc voltage; the magnitude and order of programming the welding current; the rateof closure of the arc gap during upset, which affects the formation of welds have been determined. The experimental industrial technology for welding of thin-walled tubular details with a diameter up to 212 mm for thepurpose of its industrial use and the concept of the welding equipment has been developed, patents for the invention have been received.Conclusions. The mechanical and metallographic tests have shown that the properties of welded joints are at the level of the properties of the base metal. The use of press welding technology for tubular parts increases productivity and automates the welding process. The influence of the bandwidth of the liquid molten metal in the arc gap, while heating, on the formation of welded joints of pipes has been experimentally established. The main technological parameters and their influence on the quality of welded joints in the process of heating, the ends, and the upset of thin-walled tubular parts have been determined. Experimental industrial technology for press welding of thin-walled tubular parts has been developed and industrial tests have been conducted, in accordance with the customer's requirements.

A multiobjective optimization of the welding process in aluminum alloy (AA) 6063 T4 tubes used in corona rings through normal boundary intersection and multivariate techniques

The welding process in aluminum is a complex process that commonly presents several issues such as weld bead discontinuity, cracks, and lack of penetration. Thus, an accurate specification of the parameters in order to achieve optimal values for the investigated responses is aimed by the industry. The present paper proposes the application of a multiobjective optimization approach considering multivariate constraints based on the simultaneous confidence intervals and the elliptical region of the correlated data. Structured experiments for the welding process of aluminum alloy (AA) 6063 TA tubes used in corona rings were performed according to a face-centered composite design with 4 factors, wire feed rate (Wf), arc voltage (V), contact tip to the workpiece distance (Ct), and motor frequency (Fr), resulting in 31 experiments. Poisson regression was applied to model the values of yield (Y), dilution (D), reinforcement index (RI), and penetration index (PI), allowing to estimate the optimal individual values with regard to the multivariate constraints. Rotated factor scores were obtained in order to replace the original data, and therefore, the factor multivariate square error was used as objective functions to be minimized through normal boundary intersection method. A satisfactory weld bead with large values of PI, D, and Y and a small value of RI was reached as prespecified by the manager of the process.

Numerical Simulation of Temperature Field and Temperature Control of DC Arc Plasma Torch

In order to study and analyze the internal heat transfer process of DC arc plasma torch, a two-dimensional axisymmetric model of DC arc plasma torch was established based on magnetohydrodynamics and heat transfer theory. The finite element analysis software COMSOL was used to simulate the temperature field under different conditions. The results show that when the terminal current is constant, the DC plasma arc voltage and the average temperature of the torch outlet increase with the increase of nitrogen standard flow rate, and the maximum temperature in the plasma torch decreases with the increase of nitrogen standard flow rate. When the standard flow rate of nitrogen is constant, the arc voltage decreases with the increase of arc current, and the average temperature of plasma torch exit and the maximum temperature in the torch increase with the increase of arc current. The analysis of simulation data provides theoretical guidance for the temperature control of experimental DC plasma torch.

Effect of Arc Chute on DC Current Interruption by Liquid Nitrogen in HTS Electrical System of Distributed Propulsion Aircraft

The distributed propulsion aircraft with HTS electrical system is a novel concept for future airliners, which can reduce by more than 70% fuel burn and NO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> emissions. The circuit breakers ensure the security of this novel aircraft by isolating electrical faults timely. Solid-state circuit breakers (SSCBs) are preferred due to their fast response and high performance in the cryogenic circumstance. However, the high conduction loss of SSCBs impedes their further application. A mechanical switch using liquid nitrogen (LN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) as an arc extinguishing medium shows excellent DC current interruption performance. The LN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> switch is characterized with extremely low contact resistance, and the proper use may reduce the conduction loss of power switches significantly. Nevertheless, the effect of metal type arc chutes on the arcing process in the LN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> is still not clear. Thus the objective of this paper is to understand the effect of metal type arc chutes on the current interruption performance of LN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> . Silicon iron arc chutes are employed. Neodymium (NdFeB) magnets are used to stretch the arc into the arc chutes. The maximum interrupting current is 1 kV/ 2 kA when only magnets are applied. Further applying the arc chutes leads to a significant drop in the arc voltage and interruption performance. Since the high relative permeability of silicon iron weakens the magnetic field acting on the arc, metal type arc chutes are not recommended. 1 kV / 10 kA fault current is successfully cleared by the combination of resistance type superconducting fault current limiter (R-SFCL) and LN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> switch with magnets, during which the R-SFCL responds to the fault within 420 μs, compensating the long clear time of the LN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> switch.