Arc Power Research Articles

Fuzzy Logic Controller for Power Control of an Electric Arc Furnace

Electric Arc Furnaces (EAFs) are widely used in the steel manufacturing industry to melt scrap steel by employing a large number of electric arcs. EAFs play an important role in ensuring the efficient production of steel. However, their nonlinear and variable load characteristics have a significant impact on power quality. Because the active power of an electric arc depends on its length, a system for controlling the electrode positions is necessary. This paper presents a control system based on a fuzzy logic controller for the active power control of an electric arc furnace. Individual simulation scenarios were chosen with both reference values and the process taken into consideration. The reference, constant value, step variation, and the sequence of step variation were investigated, as well as step disturbances and the sequence of step disturbances from the viewpoint of the process. Furthermore, the procedure of changing the tap on a transformer was investigated. The proposed solution minimizes the time required for charge elaboration, but the main benefit is that there are no additional costs in the implementation process because the installation remains identical, with the only changes being improvements to soft control management.

DETERMINATION OF OPTIMAL CONDITIONS FOR HERMETIC WELDING OF THIN FOILS WHEN USED IN MEMBRANE-TYPE STRUCTURES

Purpose. Development of optimal technology for welding thin-walled shells mode of 12Х18Н10Т steel (δ=0.15 mm), working at alternating loads. Research methods. Research methods. For welding automatic argon-arc welding (AAAW) equipment was used for of orbital welding, which includes a MW 2600 current source (FRONIUS) with software control unit and welding head of closed type MW40. Research warks showed that this type of welding is not enough for such small thicknesses concentration of the welding arc, which does not allow stable forming of the bath and obtaining solid uniform seam. A special robotic complex was used for microplasma welding STARWELD 190H, which includes: a power source for the regular arc INV 50; source main arc power supply INV 190; SIEMENS Simatic S 7-300 control unit; robot CR3-535M (MITSUBISHI); manipulator and HPH 80 plasmatron. Welding quality control was carried out by visual inspection and metallographic examination. Taking into account the conditions of operation of the parts, according to the technical conditions of the drawing, it was also provided pneumohydraulic control method. Obtained results. Visual inspection the outer surface of the welds showed the absence of defects in the form of pores, cracks, shells, no fusions, undercuts, etc. The geometric dimensions of the weld met the requirements of the standard documentation valid at the enterprise. Metallographic studies of the boxes membranes, welded by microplasma welding, gave a positive result. Defects of metallurgical character were not found in the welds. Practical value. The optimal method of welding that can be applied is determined for the manufacture of thin-walled membrane structures, from the point of view of manufacturability and economy expediency It has been established that microplasma welding allows obtaining a hermetically tight seam, when the thickness of parts to be welded is about 0.15 mm. The performance of welded membrane boxes is confirmed in the barostatic valve of an aircraft engine. It is established that micro plasma welding can be used in the manufacture of thin-walled shells made of 12X18H10T steel (δ=0.15 mm), which work at variable loads. The technological process of welding is introduced into the series production.

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.

Review and Analysis of Modern Laser Beam Welding Processes.

Laser beam welding is the most modern and promising process for the automatic or robotized welding of structures of the highest Execution Class, EXC3-4, which are made of a variety of weldable structural materials, mainly steel, titanium, and nickel alloys, but also a limited range of aluminum, magnesium, and copper alloys, reactive materials, and even thermoplastics. This paper presents a systematic review and analysis of the author's research results, research articles, industrial catalogs, technical notes, etc., regarding laser beam welding (LBW) and laser hybrid welding (LHW) processes. Examples of industrial applications of the melt-in-mode and keyhole-mode laser welding techniques for low-alloy and high-alloy steel joints are analyzed. The influence of basic LBW and LHW parameters on the quality of welded joints proves that the laser beam power, welding speed, and Gas Metal Arc (GMA) welding current firmly decide the quality of welded joints. A brief review of the artificial intelligence (AI)-supported online quality-monitoring systems for LBW and LHW processes indicates the decisive influence on the quality control of welded joints.

Закономерности износа плазмотронов при плазменной резке толстолистового проката на токе обратной полярности

The introduction describes the features of the process of plasma cutting of various metals and alloys using reverse-polarity plasma torches with and the features of cutting thick sheets. The purpose of the work is to study the wear process of plasma torches operating on reverse polarity current when cutting thick rolled sheets of aluminum and titanium alloys. Research methods include optical and scanning electron microscopy, filming of the cutting process and visual inspection of plasma torch elements after receiving specimens. Results and discussion. The section shows the appearance of the main working elements of the plasma torch after cutting in various modes, which led to both stable and gradual wear and to catastrophic failure of the plasma torch. The results of structural studies of the main characteristic zones of nozzles and electrodes after cutting are presented. The studies carried out made it possible to establish the main reasons for the failure of the working elements reverse-polarity plasma torches. The causes of catastrophic failure of plasma torches include failure to maintain the gap between the nozzle and the electrode and melting of the channel of gas supply into the discharge chamber. The wear of nozzles and electrodes in a stable mode can be intensified due to abnormal operation of the starting arc, the presence of manufacturing inaccuracies and excess gas pressure. In conclusion, the main conclusions based on the results of the research are formulated. The process of wear of electrodes, nozzles and body elements of plasma torches during operation at high electric arc power values is described.

Failure mechanism and thermal runaway behavior of lithium-ion battery induced by arc faults

As the widespread of lithium-ion battery systems such as electric vehicles and energy storage systems, the number of safety incidents due to electrical faults are increasing. Many accident reports have demonstrated that arc faults have become one of the main triggers of LIB system accidents, however, the related studies are inadequate. In this study, an arc imitation system is employed to investigate the influence of different arc energies on battery safety valve, as well as the electrochemical characteristics of faulty batteries. The results show that the minimum arc power to breach the safety valve ranges from 110 to 441 W. The maximum temperature rise rate on the battery surface can exceed 15 °C/s with arc power of around 1000 W. Further, the testing of in-situ and ex-situ indicate the faulty batteries undergo degradation and failure due to that moisture in the air enters the battery interior, resulting in increased internal resistance, loss of active materials and cyclable lithium. Finally, the faulty battery has no valve opening during thermal runaway, and the ignition time is four hundred seconds earlier than that of the normal battery, indicating more severe fire dangers. The results are valuable for safety design of battery systems in relation to arc faults, as well as the characteristic for fault detection and early warning.

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.

A comparative study on the structure and properties of TiAlSiN coatings deposited by FCVA and HiPIMS

The TiAlSiN coating has garnered significant interest due to its exceptional hardness, high oxidation resistance temperature, robust film-substrate bond strength, excellent wear resistance, and superior thermal stability. The energetic ion beam technology has emerged as a potent method for fabricating thin films. In this study, TiAlSiN films were deposited utilizing magnetic filtered cathode vacuum arc (FCVA) and high power pulsed magnetron sputtering (HiPIMS), and their respective structures and properties were meticulously investigated and contrasted. Upon comparative analysis, it was observed that the elemental composition of the FCVA films underwent a pronounced change with the same. Depending on the desired film thickness, the deposition rate of the FCVA system was found to be superior over the same duration. The crystallographic structure of the films fabricated by both systems predominantly featured an fcc-(Ti,Al)N phase. Notably, at an N2 flow rate of 40 sccm, the film deposited via HiPIMS demonstrated remarkable hardness (27.04 GPa), an elevated H/E* ratio (0.103), and superior wear resistance (7.24×10−6 mm3/N∙m). The films produced by these two deposition methods exhibited discernible differences and clear trends in hardness, adhesion strength, and tribological properties. This research provides a valuable reference for selecting the most appropriate deposition process and parameters based on the desired attributes of the coatings.

Enhancing the electrical performance of AgNi contact material by doping Ag2WO4

To improve the anti-welding ability of AgNi contact material, the Ag2WO4 was doped for the Ag-8 wt%Ni contact material. The electrical contact tests were performed at 36 V/25A for 5000 operations on an electrical testing system, and the welding and material transfer behaviors were studied. The results show that doped Ag2WO4 significantly decreases the welding frequency (115 times to 34 times) and welding force (max 0.49 N to 0.13 N) for the Ag-8 wt%Ni contact material, which is derived from the fine eroded morphology acted by Ag2WO4. Furthermore, doping Ag2WO4 increases the material transfer from anode to cathode, which can be attributed to the influence of Ag2WO4 on the plasma ion density, and the balance of metallic and gaseous arcs reflected from the arc power.

The Effect of Energy Parameters of Power Sources on the Structure and Properties of Permanent Joints at Manual Arc Welding

The study presents the results of the research into the effect of the dynamic properties of inverter and diode power sources of welding arc power supply on the stability of melting and transfer of electrode metal into the weld pool. The principal energy parameters of the power source include the rates of rise and fall of short-circuit current, the ratio of arc burning current to short-circuit current, and other related factors. It has been demonstrated that an increase in the rate of change of these parameters within one welding mode microcycle alters the properties of heat and mass transfer, increases the frequency of electrode metal droplet transfer, reduces the size of transferred droplets in the weld pool and the duration of their stay on the electrode end under the influence of the high temperature of the welding arc, and the duration of short circuits. The increase in the mass fraction of alloying elements at their transition from the coated electrode to the weld metal is demonstrated to depend on the rate of change of the main energy parameters of one welding mode microcycle of the inverter power source in comparison with the diode rectifier. An enhancement in the structural integrity and properties of permanent joints during welding has been observed when using an inverter power source for the welding arc with high dynamic properties.

Breakthrough in atmospheric plasma spraying of high-density composite electrolytes: Deposition behavior and performance of plasma-sprayed GDC-LSGM on porous metal-supported solid oxide fuel cells

The potential application of plasma spraying in the preparation of ceramic electrolyte for porous metal-supported solid oxide fuel cells (SOFCs) is highlighted by its ability to eliminate the need for a high-temperature sintering process. However, the challenge of achieving highly dense electrolytes through plasma spraying remains to be addressed. In this study, a novel electrolyte for porous metal-supported SOFCs (PMS-SOFCs) is developed. This involved the preparation of a highly dense structure of gadolinium-doped ceria (GDC)-lanthanum strontium gallium magnesium oxide (LSGM) composite coating using plasma spraying under atmospheric conditions. The composite electrolyte is prepared using atmospheric plasma spraying (APS). The addition of the low-melting-point LSGM phase enhanced the microstructural densification of the GDC-based composite coating and diminished electron loss in a reducing atmosphere, thereby improving the cell's open-circuit voltage. At 36 kW plasma arc power, the single cell with composite electrolyte exhibited a maximum power density of 371 mw/cm2 at 750 °C and achieved the highest open-circuit voltage (1.03 V) at 600 °C. Moreover, the open-circuit voltage remained stable over a 100-h test. These findings suggest that using APS to deposit a composite electrolyte with added low-melting-point secondary phases presents a promising approach for achieving relatively high OCV in PMS-SOFCs based on cerium oxide electrolytes.

The Experimental Design of a Spring Coil Compressor Remover for Automobile

This study examined various types of coil spring compressors in the automobile industry. A coil spring compressor for compressing a coil spring during the assembly of subassemblies of automotive suspension systems, having a head jaw positioned above a base and movable concerning the base. The coil spring compressor is provided with a pair of guide bars suspended from the head plate and on which a slidable carriage is mounted. The carriage carries a pair of compressing assemblies facing each other in vertical positions and positioned at both the upper and lower parts of the coil spring. Each assembly comprises a pair of compressor arms interconnected with each other. Each compressor arm is provided with a jaw mount to which a compressing hook is adjustably attached. The jaws are introduced between a few successive turns of the coil spring by operating handles provided on the compressor arms. The purpose of this design is to be used on various types of suspension disassembly and assembly of vehicles, the tool includes the upper and the lower jaw which by the smooth turning of the screw lowers to compress the coil spring or turns to release the compressed coil spring. The new design was made from mild steel and the tools used for the construction were an electric arc welding machine, power, and hand hacksaws, the bench vice, assorted hammers, vice, etc. The findings indicated that the new design is more efficient than the existing one. It was also recommended that car owners who visit the workshop should insist on the use of the right compression tool in the disassembly and assembly of their suspension systems.

Modelling of plasma discharge in a filament negative ion source

Most of the currently operating Negative ion Neutral Beam Injectors (N-NBIs) exploit filament powered sources for the generation of beam ions. Being widely used in fusion experiments, the filament arc technology has been thoroughly investigated and optimized over the years, allowing to achieve excellent performances in terms of extracted beam optics. The source geometry, the magnetic field topology and the arc power strongly influence both the plasma discharge and the background gas properties and, consequently, the beam features. In this framework, this contribution describes a numerical investigation of the plasma properties in a filament-powered negative ion source, performed by means of a 2D3V Particle In Cell-Monte Carlo Collisions (PIC-MCC) code. Specifically, we discuss plasma formation by the thermionic electrons emitted by the filaments, investigating their interaction with the background gas. We also study the plasma diffusion through the magnetic filter field and how the latter modifies plasma density, electron temperature and plasma potential along the axial direction when approaching the plasma facing electrode.

TRIUMF’s H-/D- Ion Source Development to Date

The TRIUMF Stable Ion Source group has been developing negative and positive ion sources for decades, including a few arc-discharge H-/D- ion sources and a microwave-driven H-/D- ion source for medical cyclotrons [1] and other applications. The smallest ion source with a 125 cc plasma chamber can produce up to 5 mA continuously. The largest ion source with a 1200 cc plasma chamber is able to produce 60 mA with increased arc power and enhanced magnetic confinement. The filament-less microwave ion source is capable of producing up to 5 mA H- current for years without any manual intervention. A historical overview of H-/D- source development at TRIUMF is presented. A summary of employed optical and diagnostics components is also presented

Discharge characterization of two-region arc plasma (TRAP) ion source

The Korea Atomic Energy Research Institute (KAERI) is developing a novel Two-Region Arc Plasma Ion Source (TRAP) as a negative hydrogen (deuterium) ion source for a Neutral Beam Injection (NBI) system in a fusion tokamak. The TRAP ion source is based on a two-region configuration, comprising a high energy electron region that creates highly vibrationally excited molecules and a low electron temperature region that generates negative ions by attaching electrons to molecules. This configuration can be achieved by optimizing the filament position and magnetic cusp field. In order to optimize the TRAP configuration, the plasma parameters are investigated under various operating conditions, such as filament position, gas pressure, and arc power. Electron density and temperature are determined using Langmuir probe measurements. In this paper, the detailed experimental results are described and discussed.

The Phenomenon of a Cathode Spot in an Electrical Arc: The Current Understanding of the Mechanism of Cathode Heating and Plasma Generation

A vacuum arc is an electrical discharge, in which the current is supported by localized cathode heating and plasma generation in minute regions at the cathode surface called cathode spots. Cathode spots produce a metallic plasma jet used in many applications (microelectronics, space thrusters, film deposition, etc.). Nevertheless, the cathode spot is a problematic and unique subject. For a long time, the mechanisms of spot initiation, time development, instability, high mobility, and behavior in magnetic fields have been described by approaches that caused some controversy. These spot characteristics were discussed in numerous publications over many years. The obscurity and confusion of different studies created the impression that the cathode spot is a mysterious phenomenon. In the present work, a number of typical representative publications are reviewed with the intention of clarifying problems and contradictions. Two main theories of cathodic arcs are presented along with an analysis of the experimental data. One of the approaches illustrates the cathode heating by Joule energy dissipation (volume heat source, a sharp rise in current density, etc.), nearly constant cathode potential drop, and other certain initial conditions. On the other hand, a study using a mathematically closed approach shows that the spot initiation and development are determined not by electron emission current rise but by a rise in arc power density, affecting heat sources including the energy of ion flux to the cathode (surface heat source).

Enhanced anti-welding and arc erosion performance of Ag-8 wt%SnO2 contact material with different addition of graphene nanoplatelets

To improve the welding resistance of Ag-8 wt%SnO2 contact material at large current, the graphene nanoplatelets (GNPs) was selected as the additive, and Ag-8 wt%SnO2 contact materials with different GNPs addition were prepared by powder metallurgy route. The electrical contact tests were performed under 36 V/16 A and 36 V/25 A, the welding, material transfer behavior and their mechanism were investigated combined with the analysis of arc duration, arc power and eroded morphology. The results show that 0.2 wt% GNPs addition decreases the welding frequency and welding force significantly, this can be attributed to the arc extinction effect and the weaken effect of the welding area. However, the excessive GNPs addition in turn aggravates the welding, the reason is that excessive GNPs addition weakens the bond between eroded layers, resulting in the decrease of arc stability and the generation of the small protrusion which cause the concentration of the contact stress and the electric field, which further results in the serious welding. Furthermore, 0.2 wt% GNPs addition decreases the mass loss rate, increasing the combination performance of Ag-8 wt%SnO2 contact material.

Experimental Study on Wire Melting Control Ability of Twin-Body Plasma Arc

The twin-body plasma arc has the decoupling control ability of heat transfer and mass transfer, which is beneficial to shape and property control in wire arc additive manufacturing. In this paper, with the wire feeding speed as a characteristic quantity, the wire melting control ability of twin-body plasma arc was studied by adjusting the current separation ratio (under the condition of a constant total current), the wire current/main current and the position of the wire in the arc axial direction. The results showed that under the premise that the total current remains unchanged (100 A), as the current separation ratio increased, the middle and minimum melting amounts increased approximately synchronously under the effect of anode effect power, the first melting mass range remained constant; the maximum melting amount increased twice as fast as the middle melting amount under the effect of the wire feeding speed, and the second melting mass range was expanded. When the wire current increased, the anode effect power and the plasma arc power were both factors causing the increase in the wire melting amount; however, when the main current increased, the plasma arc power was the only factor causing the increase in the wire melting amount. The average wire melting increment caused by the anode effect power was approximately 2.7 times that caused by the plasma arc power. The minimum melting amount was not affected by the wire-torch distance under any current separation ratio tested. When the current separation ratio increased and reached a threshold, the middle melting amount remained constant with increasing wire-torch distance. When the current separation ratio continued to increase and reached the next threshold, the maximum melting amount remained constant with the increasing wire-torch distance. The effect of the wire-torch distance on the wire melting amount reduced with the increase in the current separation ratio. Through this study, the decoupling mechanism and ability of this innovative arc heat source is more clearly.

Conventional and pulsed hybrid triboelectric nanogenerator with tunable output time and wider impedance matching range

Sliding grating-structured triboelectric nanogenerators (SG-TENGs) can multiply transferred charge, reduce open-circuit voltage, and increase short-circuit current, which have wide application prospects in self-powered systems. However, conventional SG-TENGs have an ultrahigh internal equivalent impedance, which reduces the output voltage and energy under low load resistances (<10 MΩ). The Pulsed SG-TENGs can reduce the equivalent impedance to near zero by introducing a synchronously triggered mechanical switch (STMS), but its limited output time causes the incomplete charge transfer under high load resistances (>1 GΩ). In this paper, a conventional and pulsed hybrid SG-TENG (CPH-SG-TENG) is developed through rational designing STMS with tunable width and output time. The matching relationship among grid electrode width, contactor width of STMS, sliding speed, and load resistance has been studied, which provides a feasible solution for simultaneous realization of high output energy under small load resistances and high output voltage under high load resistances. The impedance matching range is extended from zero to at least 10 GΩ. The output performance of CPH-SG-TENG under low and high load resistances are demonstrated by passive power management circuit and arc discharge, respectively. The general strategy using tunable STMS combines the advantages of conventional and pulsed TENGs, which has broad application prospects in the fields of TENGs and self-powered systems.

Research on early fault detection method for a new distribution system based on automatic arc power

The assimilation of copious renewable energy sources into contemporary distribution systems has markedly transmuted fault dynamics, engendering fluctuating operational states and curtailed short-circuit currents. Consequently, incipient arc faults may herald imminent system short-circuits, obviating the complexities associated with the new distribution system's disconnection by facilitating their precocious detection. A quantitative analytical paradigm has been contrived for the nascent fault current and temperature, while theoretical scrutiny elucidates the impediments to dependable detection predicated solely on current or temperature metrics. An innovative detection methodology, amalgamating current and temperature readings and leveraging arc power as a composite indicator, has been advanced. This proposed mechanism synergizes the alacrity of the electrical signal—specifically, the zero-sequence current—with the heightened sensitivity and dependability of the thermal signal—temperature—thereby surpassing the reliability of extant approaches. The efficacy of this method has been corroborated through PSCAD simulations, empirical field data, and controlled laboratory fault experimentation.