Arc Voltage Research Articles

Effect of Heat Supplied to the Joint in the MAG Welding Process of Ferritic–Austenitic Stainless Steel 1.4462 on the Size of the Cross-Sectional Area of the Joints

In this study, the relationships between the values of the parameters included in heat input (welding current, arc voltage and welding speed) and their effects on the size of the cross-sectional areas of welds in joints made of ferritic–austenitic stainless steel using the GMAW method were determined. An attempt was also made to determine to what extent it will be possible to predict the properties of fabricated welded joints using the functional relationship describing the effect of the value of heat input on the size of the cross-sectional area of welds. The analysis of the developed mathematical models shows their suitability for explaining (and predicting) the sizes of the cross-sectional areas of welded joints depending on the values of the input parameters of the welding process. Determining the regression function and making a three-dimensional plot of it (response surface) can provide a starting point for optimizing the parameters of the welding process. The results have practical relevance, supporting weld quality control and process design in industrial conditions, especially in applications requiring high strength and corrosion resistance, in industries such as construction and offshore.

Optimal Sliding Speed and Contact Pressure Design of On-Load Tap Changer Based on Multivariate Nonlinear Regression

During the voltage regulation of on-load tap changers (OLTCs), the movement of the contacts can easily cause arcing, which may lead to erosion or malfunction. To reduce the energy and probability of arcing, we focus on designing an optimal range for the sliding speed and contact pressure of the contacts to minimize arc energy. Initially, our research introduces a novel OLTC arc testing platform to simulate the motion of static and dynamic contacts, exploring the relationship between different sliding speeds, contact pressures, and factors like arc voltage waveform, arcing rate, arc resistance, and arc energy. Subsequently, by employing multiple nonlinear regression methods, we establish functional relationships between sliding speed and arc energy, as well as contact pressure and arc energy, evaluating the fit using correlation coefficients. Finally, through analyzing their nonlinear behaviors, we determine the ideal sliding speed and contact pressure. The results indicate that when the OLTC contacts slide at an optimal speed between 89 and 103 mm/s and optimal contact pressure between 1.5 and 1.7 N, the arc energy can be minimized, thereby enhancing the performance and lifespan of the on-load tap changer. This study offers feasible insights for the design and operation of OLTCs, aiding in the improvement of power system regulation.

Influence of external AC transverse magnetic field on air arc oscillation patterns and its application in DC forced current zero techniques

Abstract Direct current (DC) circuit breakers are essential for maintaining the stability of the electric energy transmission and safeguarding the power equipment from the damage caused by the fault currents in DC power systems. The characteristics of the switching arc can be utilized in DC forced current zero techniques. This paper investigates the influence of an external alternating current (AC) transverse magnetic field on the oscillation characteristics of air arc. By confining the arc between two insulating walls and applying a transverse AC magnetic field, the arc exhibits ‘bidirectional oscillation’ and ‘unidirectional oscillation’ modes. The effects of magnetic field amplitude and frequency on the air arc oscillation characteristics are analyzed through experiments, from the aspects of the arc voltages and arc motions. It can be found that an external AC magnetic field can stabilize the arc voltage at a specific oscillation frequency. By connecting an inductor–capacitor (LC) branch in parallel with the arc and setting the LC branch’s resonant frequency equal to the arc voltage oscillation frequency, a current resonance process between the arc and the LC branch can be achieved. This resonance facilitates the creation of the arc current zero-crossing point. A test platform based on the arc oscillation characteristics is established for current interruption experiments. For system currents of 1 kA and 3 kA, the arc current zero-crossing time is controlled within 0.41 ms after applying the external AC transverse magnetic field. The experimental results verify the rationality of the proposed DC breaking scheme.

Short‐circuit current of a hydropower plant with consideration of constant switching and fault arc voltages

AbstractThe correct generator circuit breaker (GCB) dimensioning is essential for the safe and reliable operation of a power plant or generation system. The dimensioning is usually based on standardized calculation methods according to standards (IEC standard 60909‐0, IEC/IEEE standard 62271‐37‐013, IEEE Std C37), often supplemented by selected transient calculations. A non‐systematic approach can often be observed here, which does not adequately take into account significant influencing variables or operating states of the generator. This article therefore systematically examines various parameters that influence the short‐circuit current components of the generator and are relevant for the dimensioning of the generator circuit‐breaker: short‐circuit angle, operating point, impedance ratios, phase clearing, switching arc, and fault arc. The results of the current parameters most relevant to the dimensioning of the GCB were then compared for different calculation methods. Special attention was paid to the effect of the switching and fault arc, which were modelled as a constant arc voltage, and its effect on the short‐circuit currents is systematically recorded. This work aims to summarize all relevant variables that influence the generator short‐circuit current and are relevant for the dimensioning of the GCB and to present the different results based on a short‐circuit calculation according to the standard and transient calculation to create a basis for a proper dimensioning of the generator circuit breaker.

Analysis of the interactions between laser and arc due to different geometric arrangements and laser parameters in the additive manufacturing of Ti-6Al-4V

Additive manufacturing based on arc welding (=DED-Arc) has already established itself in the world of additive manufacturing. Recent process optimizations show the increased use in a hybrid process by irradiating an additional laser beam into the active arc zone. Numerous publications can be found in the literature for steel, aluminum, or bronze, in which, among other things, a strength-enhancing effect or an improved wall surface during this hybrid process is reported. The way in which the laser beam impacts the arc, at what distance, at what angle and with what spot size or focusing appears to be random in the publications and is always chosen differently in the literature. In order to close this knowledge gap, a corresponding holder for a DED-Arc torch and laser optic is developed, which allows these geometric factors to be systematically changed and also enables the titanium alloy Ti-6Al-4V to be processed in a hybrid process. By welding individual tracks and walls with different angles, distances and spot sizes of the two energy sources, a fundamental understanding of the laser-arc hybrid process is created. The results are analyzed using a high-speed camera and evaluated on the basis of surface measurements, micrographs, and power source values. This showed that the distance between the laser and the arc has the greatest effect on the additive process stability and the arc power sources values. In the range of 2–6 mm, there are, in some cases, strong fluctuations in the wire deposition and the arc voltage, so that this range should be avoided. It also showed that a wider spot sizes range of 360–600 μm can be used, whereby different ranges are recommended depending on the target size of uniform wall height or thickness. For the laser incidence angle, the most uniform walls across all tests are achieved at 20°. As the angle of incidence becomes flatter, the walls become more irregular, although there is no linear relationship or areas that should be avoided at all.

Dissimilar MIG Welding Optimization of C20 and SUS201 by Taguchi Method

This study looks at how welding intensity, speed, voltage, and stick-out affect the structural and mechanical characteristics of metal inert gas (MIG) welding on SUS 201 stainless steel and C20 steel. The Taguchi method is used to optimize the study’s experiment findings. The results show that the welding current has a more significant effect on the tensile test than the welding voltage, stick-out, and welding speed. Welding voltage has the lowest influence. In addition to the base metals’ ferrite, pearlite, and austenite phases, the weld bead area contains martensite and bainite microstructures. The optimal parameters for the ultimate tensile strength (UTS), yield strength, and elongation values are a 110 amp welding current, 15 V of voltage, a 500 mm.min−1 welding speed, and a 10 mm stick-out. The confirmed UTS, yield strength, and elongation values are 452.78 MPa, 374.65 MPa, and 38.55%, respectively, comparable with the expected value derived using the Taguchi method. In the flexural test, the welding current is the most critical element affecting flexural strength. A welding current of 110 amp, an arc voltage of 15 V, a welding speed of 500 mm.min−1, and a stick-out of 12 mm are the ideal values for flexural strength. The flexural strength, confirmed at 1756.78 MPa, is more than that of the other samples. The study’s conclusions can offer more details regarding the dissimilar welding industry.

Automated process control in electric arc furnaces in the aspect of digital twin technology

An approach to managing the main modes of smelting steel in heavy-duty electric arc furnaces (EAF) using digital twin technology was defined and formulated. It was noted, that the existing power regulators do not have the function of balancing the effective power of phases and, accordingly, electric arcs because they are focused on working with a certain average value of the signal. It is proposed to use the analysis of dynamic characteristics based on instantaneous values of input parameters instead of operating ones, as it’s usually implemented in most devices. This allows us to obtain more accurate data on the arc state and reduce the amount of time and computing power required to obtain a result and form recommendations. Based on the data obtained as a result of long - term observations of the heavy-duty EAF-135 operation, the relationship of the constant component of the arc voltage (CCAV) with the metal oxidation is shown. An example of its use as a criterion for controlling the melting oxidative stage is given. This reduces the consumption of electrochemical sensors for each melting in the case of serial metal production. Based on the recorded data, it is possible to timely determine the unevenness of the arc power release between the furnace electrodes and issue recommendations on gas burners operation regulating to equalize the rate of scrap melting at electrodes with less power release. The authors propose the idea of using digital twins based on models of the active power distribution across the melting bath zones and dependence of metal oxidation on oxygen blowing for monitoring and controlling the electric mode and the oxygen blast mode at the oxidative stage of the melting process. Simplified schemes of these twins are given.

Operating voltage of a W-fuzz cathode arc and the mass/charge composition of the arc plasma depending on the fuzz thickness

The arc operating voltage and the mass/charge composition of the arc plasma were measured for W-fuzz samples with different fuzz thicknesses at different numbers of arc pulses. It was found that the formation of a fuzz structure led to a significant decrease in the arc operating voltage within the first few arc pulses. With an increase in the number of pulses, the operating voltage and the mean charge of tungsten ions in the arc plasma increased to values characteristic of conventional tungsten cathodes. The obtained experimental data were analyzed theoretically using an empirical cohesive energy rule and a magnetohydrodynamic model of the ionization processes occurring in a cathode plasma jet.

Improving the product of strength and ductility and corrosion resistance by adding He shielding gas in the CMT additive manufacturing process of Ti6Al4V

The cold metal transfer additive manufacturing (CMTAM) of titanium alloys presents a promising solution for the efficient fabrication of large titanium alloy armor components. In this study, different proportions of He gas were added to the welding shielding gas used in the CMTAM of Ti6Al4V, aiming to improve forming quality, the product of strength and ductility and corrosion resistance. Simultaneously, the influence of different He contents on the microstructure, mechanical properties, and corrosion behavior of CMTAM of Ti6Al4V was explored. The research revealed that during the process of CMTAM of Ti6Al4V, as the proportion of He as the shielding gas increased, the arc voltage increases, and the arc becomes more stable. Meanwhile, the wettability of the weld pool improves, resulting in a more spread out weld pool. The fabrication precision of the built material also improved. Microstructural observations indicate that the prior-β grain size gradually increased with the increase in He proportion, the heat input for additive manufacturing also increased，and the martensitic α’ transformed into a basketweave α+β structure. The length and width of the α phase increased, the texture intensity decreased, and the Schmid factor increased. Tensile tests were conducted on samples with different He proportions showed that as the He proportion increased, within the component resulted in a noteworthy enhancement in the product of strength and ductility increase exceeding 50 %. This suggests that He as the shielding gas addition can effectively optimize the strength-plasticity balance in additive manufactured titanium alloys without the need for post-processing heat treatment. Electrochemical tests were conducted in a 3.5 wt% NaCl solution revealed that the addition of He gas significantly improved the corrosion resistance of Ti6Al4V. Specifically, the corrosion resistance was optimal when the shielding gas composition was 50 %He+50 %Ar, far surpassing that of cast Ti6Al4V.

Experimental and model analysis of the thermoelectric characteristics of serial arc in prismatic lithium‐ion batteries

AbstractAiming at the electrical safety problems of lithium‐ion battery system due to series arc fault, a finite element simulation model of square battery under series arc fault is established based on the magnetohydro‐dynamic equations. The arc voltages at different electrode spacings are analysed, and the electric field distribution, magnetic field distribution, arc temperature and flow velocity around the arc are investigated to determine the maximum values and locations of the electric field strength, magnetic density, arc temperature and flow velocity at the time of the arc fault. Then, on the basis of the series arc experimental platform, determine the value of the arc starting voltage and the critical power supply voltage that produces a stable arc, analyse the evolution of the arc burning time with different loop currents, the evolution of the arc of the separation gap, and then summarise the effect of the disaster on the battery. Finally, the errors of simulation and experimental arc voltage and battery surface temperature are analysed to verify the accuracy of the model.

Comprehensive Experimental Database and Model Fitting for Electric Arc Behavior in Aircraft Environments

The More Electric Aircraft (MEA) paradigm advocates weight reduction by transitioning to electrical components, resulting in increased system voltage and higher arc fault risk. This paper presents a methodology for creating a database of nearly one thousand tests simulating parallel arc faults, using Andrea's arc model for accurate representation. Objectives include the creation of a robust experimental database and the use of a simplified model to analyze arcing behavior. The setup follows the UL 746A standard and considers various pressure and electrode separation conditions. The database includes 960 experiments with PVC and PTFE materials, and model fitting ensures accurate representation of arc currents and voltages. Error analysis shows consistent model performance across materials and highlights sensitivity to electrode spacing, pressure, and source voltage. The paper concludes with a clear 30% error threshold for model validity, enhancing the understanding of the applicability of Andrea's model under various experimental scenarios in aircraft environments.

Penetration state recognition for tungsten inert gas welding via an alternating cusp-shaped magnetic field-assisted molten pool-oscillation

To ensure optimal penetration in direct current (DC) argon tungsten arc welding, a method was proposed to recognize the molten pool penetration during molten pool oscillation under alternating cusp-shaped magnetic field (ACSMF). An arc discharge model is established to analyze the oscillation mechanism of the molten pool under ACSMF. The periodic variation of arc shape induces the periodic oscillation to establish a mapping relationship with the fluctuation of arc voltage waveform. At the excitation current of 3 A and frequency of 10 Hz, the arc voltage waveform undergoes abrupt changes at 1.26 V and 1.37 V, corresponding to the critical and the full penetration states, respectively. The errors in identifying moving penetration are 0.8 % and 0.7 %, with a full penetration weld, demonstrating a penetration rate of 100 %, indicating effective penetration recognition. Arc sensing technology for tungsten inert gas (TIG) welding under ACSMF is poised for gradual application in single-side welding and double-side forming of medium and thick plates. It is anticipated to evolve towards real-time identification technology for molten pool penetration monitoring.

Deconvolution-based correction of pre-strike arc voltage measurement in medium voltage switches

Abstract Switching arc characterization, e.g. measuring the arc voltage and current, is crucial for assessing the performance of power switchgears under different working conditions. This is especially challenging for short circuit current making as one of the most severe operations for medium voltage load break switches. By closing the switch, a short circuit current flows through the arc which is ignited by the electrical breakdown in the gap between contacts before the contacts touch. This results in an abrupt change from the rated voltage of the power network, i.e. tens of thousands of volts, to the switching arc voltage, i.e. a few tens of volts and ultimately zero when the contacts touch. The inherent response of the measurement system to this very large step preceding the arc formation overlaps with the switching arc voltage and results in unrealistic arc voltages which makes correction of the distorted voltage waveform necessary. In this paper, a post processing method based on deconvolution correction technique, i.e. deconvolution of the measured voltage in time and frequency domains, is examined using experimentally determined impulse responses of the measurement system. To demonstrate its effectiveness, this method is applied to three different measurement system configurations with various step responses. The results show practically identical deconvoluted (corrected) voltage waveforms in all three measurement systems, although the directly measured waveforms have significant differences. The corrected arc voltage waveforms are in agreement with the indirect measurements proposed in previous studies.

Online welding status monitoring method of T-joint double-sided double arc welding based on multi-source information fusion

In modern manufacturing, double-sided double arc (DSDA) welding brings advantages in properties and efficiency for T-shaped joints. However, the double-side forming makes it difficult to detect the imperfections and ensure weld joint quality, which few studies have covered. Most existing methods deal with single-arc welding with limited sensing sources. To fill the gap, an online welding status monitoring method for DSDA welding is proposed based on the fusion of welding current, arc voltage, arc sound, and weld pool images. In pre-processing, the automatic weld pool region of interest (ROI) detection method based on the lightweight YOLO-L model and the waveform denoising algorithm are designed. In feature engineering, waveform signals are analyzed in both the time and frequency domain. A weld pool feature extractor based on a convolutional neural network (CNN) is proposed with good effectiveness and interpretability. The output feature combination is refined by Fisher-based selection and evaluation. In model building, an ensemble learning model based on three high-fit basic learners is proposed, with an accuracy of 98.538 %. The proposed model shows significant advantages over the single basic classifier and other ensemble methods. Experiments verify high precision and robustness, laying a foundation for accurate real-time monitoring of DSDA welding production.

Effect of laser-assisted irradiation on plasma electrolytic oxidation of titanium alloys: Arc spot evolution characteristics and photoelectric synergistic mechanisms

Laser irradiation can be employed as an auxiliary energy field to optimize functional plasma electrolytic oxidation (PEO) coatings. Herein, the mechanism of the effect of laser-assisted irradiation on the morphology and composition of ceramic coatings prepared by PEO of titanium alloys in electrolytes with sodium tetraborate-based is discussed from the perspective of plasma arc spot evolution and photoelectric synergistic effect. X-ray diffraction (XRD), transmission electron microscopy (TEM), Mott-Schottky (M-S), scanning electron microscopy (SEM), and atomic force microscopy (AFM) were used to analyze the coating characteristics. The results showed that laser-assisted irradiation promoted the oxidation of the coatings, accelerated the conversion of the anatase phase to the rutile phase, reduced the oxygen vacancy defects and formed the "ant nest" porous microstructure. Monitoring of the voltage, electric field, and plasma discharge arc spot indicated that laser-assisted irradiation restricted the electric field diffusion on the anode surface, reduced the termination voltage, and significantly increased the intensity (maximum discharge percentage increased from 14.238 % to 20.358 %) and uniformity of distribution of the plasma discharge. Instantaneous photoresponse curves and electrochemical impedance spectroscopy confirmed that the PEO coatings exhibited fast and sustained photoelectric response under simultaneous laser irradiation, progressively enhanced with increasing laser irradiation energy. The photogenerated electrons excited by the semiconductor TiO2 coating under the simultaneous irradiation of laser can be used as the initial carriers of the electron avalanche, which induces the generation of a plasma on the surface of the anode and thus enhances the plasma discharge behavior, which is the fundamental reason for the optimization of the coating characteristics.

Effects of Heat Input and Intertrack Overlap on the Microstructure and Properties of Inconel 686 Weld Overlays.

The objective of this study was to investigate how weld overlays with nickel superalloys are important for the integrity, due the high temperatures and corrosive environments that can be experienced in mineral processing environments, of mining and processing equipment. The Ni-Cr-Mo superalloy Inconel 686 overlays are fabricated through automatic gas metal arc welding with variations in arc voltage and travel speed (i.e., heat input), and they have overlap between adjacent weld tracks for applications in the mining and minerals sector. The impact of variations in the process parameters and the size of the weld overlapping on the dilution, solidification morphology, microsegregation, and microhardness were investigated. Both geometric and chemical composition definitions were used to quantify the extent of the weld dilution. Subsequently, the weld geometry and dilution were correlated with the solidification microstructure and phase transformations. The maximum dilutions were measured to be 13.63% (1/2 overlap, 5.96 kJ·cm-1) and 15.39% (1/3 overlap, 4.77 kJ·cm-1), which shows that less of an overlap increases the dilution level. Scanning electron microscopy and chemical composition analysis revealed that an increase in weld heat input and dilution level led to higher levels of microsegregation for Mo and Cr, as well as the volume fraction of Mo- and Cr-rich phases in the interdendritic/intercellular regions in the overlay layer. Analysis of the weld overlays in the current study revealed strong and unprecedented connections between the weld overlay process conditions, the resultant metallurgy (i.e., dendrite arm spacing, microsegregation, and phase formation), and the hardness of the overlay. It was concluded that the optimal weld overlays in the processing window studied in this investigation were fabricated at mid-level heat inputs (i.e., 4-5 kJ·cm-1) and a 1/2 track overlap.

Study on the influence of transverse magnetic field on the arc and reignition characteristics of HVDC relays

It is of great significance to clarify the influence of transverse magnetic field (TMF) on arc control in high-voltage direct current (HVDC) relays. In this paper, the influence of TMF in a wide range of 0–140 mT on the arc characteristics of HVDC relays is studied, the experimental observations of arc reignition are carried out and the effect of arc reignition on contact erosion, the criterion of arc reignition and the mechanism of TMF enhancement on arc reignition are further analyzed. The results show that the TMF enhancement is beneficial for shortening the arc voltage stagnation duration and accelerating the speed of arc elongation, arc dispersion and dispersed arc motion, thereby improving the arc extinguishing performance. However, higher TMF leads to more severe and earlier arc reignition, as also shown in the experimental observations. The arc reignition further causes a sudden drop in arc voltage, prolonged arc duration and uneven contact erosion. To evaluate the occurrence of arc reignition caused by TMF enhancement, a simplified breakdown criterion is proposed through the defined characteristic variable C¯(t) . Based on this, the mechanism by which the TMF enhancement more easily causes arc reignition is explained, that is the higher TMF leads to an earlier and faster increase in C¯(t) and slightly reduces the breakdown threshold C¯∗(t5,D) . Further, measures to suppress the arc reignition are proposed.

Research on Arcing Characteristics of Sulfur Hexafluoride Alternative Gases in Rotating Arc Ring Main Unit

Abstract As international environmental constraints such as low carbon emissions and reduction requirements increase, there is an urgent need to seek environmentally friendly alternatives to SF6 gas. The SF6 ring main unit is widely used in the power distribution network system, highlighting the urgent need for research on environmentally friendly gas-insulated ring main units. This study simulates and compares the arc characteristics of 12 kV rotating arc ring main unit with different environmentally friendly gases, such as N2, 20%SF6/80%N2, 40%SF6/60%N2, 10%C4F7N/90%CO2. It is concluded that the arc burns most violently in N2, and the SF6 arc voltage is the highest. The specific heat at constant pressure and thermal conductivity of the gas affect the intensity of arc combustion and thus affect the arc voltage. In this paper, the causes of different gas arc characteristics are explained by analyzing the physical parameters of gas. Specifically, the isobaric specific heat and thermal conductivity of gases affect the severity of arc combustion, thereby impacting arc voltage. Moreover, viscosity plays a role in determining the rotation speed of the arc. The conclusion of this paper provides theoretical guidance on optimizing the gas component ratio of environmentally friendly gases in ring main units.

A Study on the Operation Characteristics of Arc Fault Detection Device under Arc Generation

According to the National Fire Agency's statistics in South Korea, the number of fires caused by electrical factors is increasing every year. Residual current devices and molded case circuit breakers are used to prevent electrical fires, but it is difficult to prevent electrical fires caused by arc generation. To prevent electrical fires caused by arc generation, studies on arc fault detection devices (AFDDs) and product development for commercial purposes are being conducted. However, the performance of AFDDs under real-life conditions has not been sufficiently verified. In this study, we conducted experiments on three types of AFDDs to verify their performance when a series arc is generated. Moreover, we performed arc waveform measurement and analysis. For the series arc test, we used a series arc generator based on the KS C IEC 62606 standard. We conducted arc-breaking experiments of the AFDDs with resistive and inductive loads and performed waveform measurement and analysis of the arc voltage and current.

Experimental investigation on magnetically controlled air arc oscillation characteristics for DC interruption

With the development of the direct current (DC) power grid, the research of the forced current zero techniques in DC circuit breakers is of vital importance. Through applying an external alternating transverse magnetic field to an air arc confined by insulating walls, the arc can oscillate in a specific pattern, which is defined as ‘magnetically controlled arc oscillation’ in this article. The air arc oscillation characteristics are investigated through arc voltage spectrum analysis and arc motion captured by a high-speed camera. It can be found that the arc motion can be divided into a gliding process and a stretching process. The arc voltage oscillates at a particular frequency, which is nearly twice the magnetic field frequency. The basic arc oscillation pattern can be described from the aspects of arc voltage, arc column length and arc root velocity. Furthermore, this article proposes a DC breaking scheme based on the investigated magnetically controlled air arc oscillation characteristics. The forced current zero crossing point can be created in the resonant process between the oscillated air arc and the parallel-connected inductance-capacitance (LC) commutation path. Based on the proposed DC breaking scheme, interruption experiments are carried out, and it is observed that a current of 4.2 kA can be interrupted within several milliseconds. The feasibility of DC interruption based on magnetically controlled arc oscillation has been proved.