Arc Resistance Research Articles

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.

MITIGATION OF POWER QUALITY PROBLEMS IN STEEL PLANTS USING STATIC SYNCHRONOUS COMPENSATOR

This paper focuses on mitigating various power quality issues from electric arc furnaces (EAF) in steel plants, including voltage flicker, sag, swell, and harmonics. Arc furnaces are recognized as one of the industry's most nonlinear electrically polluting loads. The proposed solution in this article to address all power quality issues caused by EAF is implementing a flexible power supply strategy known as a static synchronous compensator (STATCOM) for injecting reactive energy into the electrical grid. In this study, an experimental model of EAF is utilized based on real measurements of the variation of arc resistance and arc reactance during the melting phase. The pulse width modulation (PWM) technique is employed for current tracking feedback control to generate the required reactive current. A fuzzy logic controller (FLC) is employed for the DC bus.

Additive effect of silicone resin on direct current arc quenching performance of a model electric fuse: electrical resistivity and thermal diffusivity of high-temperature Cu/SiO2 vapor mixed with C2H6SiO vapor decomposition

Concerning DC fuses equipped with silica sand (SiO2) as an arc quenching material, the authors have proposed an additive installation of silicone resin (C2H6SiO) on a fuse-element surface to improve the limitation and interruption ability of high DC. This paper describes the additive effect of the silicone resin on the transient resistance of the arc that has formed during the DC interrupting process in a model fuse, based on the measurement result that the arc resistance markedly rises with the silicone mass coated on the fuse element. This phenomenon is subsequently explained as resulting from a thermal diffusivity of high-temperature C2H6SiO/SiO2/Cu vapor. In other words, the mixing of C2H6SiO decomposition vapor into the arc can promote vapor temperature decay through the higher thermal diffusivity, resulting in a rapid increase in the electrical resistivity of the vapor during the DC interrupting process.

Study on corrosion resistance of arc sprayed Zn–xAl (x = 19, 27, and 37) pseudo alloy coatings in salt spray environment

AbstractTo study the corrosion behavior of Zn–Al pseudo alloy coatings with different Al contents, Zn–xAl (x = 19, 27, and 37) pseudo alloy coatings were prepared by the wire arc spraying technique using Zn and Al wires with different diameters. This study investigated the microstructure, electrochemical corrosion behavior, and corrosion morphology and products of the as‐sprayed coatings after the salt spray test in 5 wt% NaCl solution. The results exhibited that the Zn–Al pseudo alloy coatings with higher Al content form denser corrosion products (Zn5(OH)8Cl2·H2O and Zn–Al layered double hydroxide) with stronger self‐shielding effect against corrosive media, thus provide better long‐term corrosion protection. Besides, electrochemical reactions are controlled by mass transfer until corrosion for 24 h, and then by a combination of mass transfer and diffusion for 96 h. Overall, it can be concluded that the Zn–37Al pseudo alloy coating in this study shows great potential to protect steel substrates from corrosion.

Simulation on Operating Overvoltage of Dropping Pantograph Based on Pantograph–Catenary Arc and Variable Capacitance Model

When the electric locomotive pantograph is dropping, the interruption of pantograph catenary contact causes electromagnetic oscillation and arcing. The frequent arc burning that occurs due to charge accumulation results in the amplitude of overvoltage increasing gradually, posing a threat to locomotive high-voltage equipment. However, the physical mechanisms and characteristics of overvoltage are still unclear. This paper proposes a simulation model of operating overvoltage due to a dropping pantograph based on the pantograph–catenary arc and variable capacitance. Distributed RLC electromagnetic oscillation is considered, which allows the real-time calculation of arc resistance and capacitance. Under the same working conditions, the error between the simulation and test results is less than 4.0%, which proves the credibility of the model. The variation law of overvoltage under different dropping speeds or catenary phases was investigated, which shows the max amplitude is 298.20 kV and steepness is 2096.80 kV/μs at 0.30 m/s speed. The waveform shows the characteristics of high amplitude and high steepness, similar to very fast transient overvoltage (VFTO). There is a sinusoidal relationship between the catenary phase and overvoltage amplitude. The closer the catenary phase to 90°, the higher the overvoltage amplitude. The research has important guiding significance for the overvoltage formation mechanism of a traction power supply system and the insulation coordination design of high-voltage equipment.

Transient Quenching Properties of Vapor Arc Formed in Silica Sand: Contribution of Vaporized SiO2 Mixture to DC Arc Extinction Performance

The current‐limiting fuse uses silica (SiO2)‐sand as arc quenching medium to increase a current‐limiting performance during the DC arc quenching process. In order to increase the current‐limiting performance of the fuse, a detailed understanding of an arc resistance rise process is necessary. This paper first carried out a 1000 A DC Cu arc quenching experiment using the silica‐sand to obtain transient change in , morphology of the arc, and arc temperature during the arc quenching process. As a result, a current decaying increased . The arc was maintained in the cavity surrounded by the fulgurite during the current decaying process. The temperature of Cu/SiO2 arc was 25–8 kK at a current region of 950–400 A during the arc quenching process. Second, we theoretically calculated an electrical resistivity , and a thermal diffusivity as vapor properties for the Cu/SiO2 vapor mixture. As typical results, the admixing of the SiO2 vapor into the Cu arc less increased of the Cu/SiO2 vapor mixture at between 25 and 5 kK. The of the Cu/SiO2 vapor mixture drastically increased due to only decay in . In contrast, the admixing of the SiO2 vapor into the Cu arc significantly increased at between 15 and 8 kK. The present results indicate that an increase in and consequent rise in thermal energy dissipation from the arc is the main role of the silica‐sand vapor mixed with Cu arc in the DC fuse during the arc quenching process. The increased thermal energy dissipation due to the SiO2 vapor admixing further decreases to rapidly rise and during the arc quenching process. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Enhanced breakdown strength of epoxy composites by constructing dual-interface charge barriers at the micron filler/epoxy matrix interface

For the advanced energy systems with ultra-high voltage and frequency, in order to improve the thermal conductivity, arc resistance and mechanical strength of epoxy-based dielectric materials, the addition of micron inorganic fillers is necessary. However, this will inevitably degrade their breakdown strength. In this work, the example of constructing dual-interface charge barriers by optimizing molecular structure at micron filler/epoxy matrix interface to capture charge and then enhance the breakdown strength of epoxy composites is reported. Results show that the Al2O3@PVDF-6/BPA system with optimized interfacial structure exhibits the breakdown strength of AC and DC voltages of 37.5 and 67.8 kV/mm, respectively, far outperforming current epoxy composites containing micron fillers. The charge trapping effects in the dual-interface charge barriers are comprehensively investigated, which is confirmed to be the reason for the improved breakdown strength. In particular, the construction of dual-interface charge barriers hardly sacrifices the thermal and mechanical properties of epoxy composites. This work unveils a scalable approach to exploring satisfied dielectric epoxy composites by dual-interface charge barriers construction at the micron filler/epoxy matrix interface.

Nano and micro co‐filled aluminum nitride/magnesium dihydrate—Silicone rubber composites for high voltage insulation

AbstractCo‐filled composites of micro magnesium dihydrate (MDH) and hydrophobically treated nano aluminum nitride (nH‐AlN) fillers in high temperature vulcanizing silicone gum are studied for thermal and dielectric characteristics for use as an insulating material in high voltage applications. The study begins with description of the compounding protocol adopted, followed by spectroscopic and optical characterization. Fourier transform infrared spectroscopy (FTIR) and energy dispersive X‐ray spectroscopy (EDX) analysis are used to verify the presence of nH‐AlN and MDH in the composites. Thermal analysis through thermogravimetric analysis revealed a stark enhancement in the onset of polymer degradation temperature, with an improvement of 208 °C achieved at 30 phr by weight loading level of MDH. Volume resistivity of 9.71 E14 Ω‐cm is obtained at 30 phr weight loading of MDH and 5 phr of nH‐AlN. AC, +DC, and −DC dielectric strength improved by 1.09, 2.06, and 1.08 times for co‐filled composites at 30 phr MDH and 5 phr nH‐AlN loading levels over unitary filled composite. Effect of dielectric polarization on dielectric constant and dissipation factor is studied at various frequencies. Limitations while conducting dry arc resistance test at standard voltage of 12.50 kV is discussed, with modification in dry arc resistance test voltage to 16.95 kV. The results are presented and discussed here.

A mixture of Si3N4 powder and SiO2 sand as a novel DC arc quenching medium for improvement of the current-limiting performance of a model electric fuse

A current-limiting and consequent direct current (DC) arc interruption requires an increase in arc resistance rarc for a DC fuse. Flattery silica (SiO2) sand has been used as an arc quenching medium in fuses for decades. However, there are few reports about a novel arc quenching medium which enables more rarc increases compared to flattery SiO2 sand. This paper uniquely selected a novel arc quenching medium based on the following material properties: (1) electrical resistivity and thermal conductivity in the solid phase, (2) the possibility of rarc increasing in the gas phase, (3) the possibility of electrical insulation after re-solidification, and (4) the cost of materials. As a result, we originally selected a powder mixture of silicon-nitride (Si3N4) and flattery SiO2 sand as a promising novel arc quenching medium. Therefore, DC interruption experiments were performed using a Si3N4/flattery SiO2 sand powder mixture under different Si3N4 concentration conditions. As a result of 1000 A DC arc quenching experiments, the utilization of Si3N4 powder with the flattery SiO2 sand successfully increased the arc resistance rarc during the arc quenching process. The increasing Si3N4 concentration exhibited a further increase in rarc during the arc quenching process. As a result of the rarc increase, the arc quenching time was significantly shortened to 30 ms for 30 wt.% Si3N4 conditions from 54 ms for the SiO2 sand conditions. In addition, utilization of Si3N4 powder achieved high insulation resistance over few MΩ after DC arc interruption. The above results clearly indicate that utilization of Si3N4 powder with flattery SiO2 sand can increase the DC interruption performance of the fuse.

Design and testing of an arc resistant power transformer with a reinforced turret

This paper presents the design and testing of a full-scale 510-kV, 415-MVA HVDC converter transformer prototype designed to withstand the resulting pressure of a 20 MJ low-impedance fault in oil occurring inside a bushing turret, which is one of the major causes of transformer fires. In addition, there is currently few studies and recommendation regarding this failure mode, which is the main motivation for initiating this study. In total, two full-scale units were designed and built: First consisting of a reinforced turret and a transformer tank designed for arc resistance using nonlinear static finite-element analysis with design pressures retrieved from explicit dynamic simulations, and a second reference unit, with a conventional turret design. Both units were then experimentally tested with a methodology based on injecting pressurized air into the water-filled units, with test equipment dimensioned and calibrated to achieve a linear injection of energy equivalent to a 23 MJ arc in oil in 100 ms. The reinforced turret and transformer tank was able to contain the arc energy and performed as predicted by the nonlinear static and explicit dynamic simulations. The energy levels used in tests are, to our knowledge, the highest reported for a low-impedance fault occurring inside a turret, demonstrating the feasibility of designing a transformer to safely withstand mentioned faults without rupturing. The suggested reinforced turret is a robust and maintenance free solution offering passive protection against internal arcing, without the need of additional relive devices. It will significantly reduce the risk of fires, improve overall safety of the substation, and has the potential to be optimized for different arc energy levels and voltage class for turrets, cable boxes and chimneys.

Assessment of the Arc Resistance of 3D-Printed Insulation Materials for Outdoor High-Voltage Applications

High-voltage electrical equipment insulation often uses composite materials like epoxy resin, cross-linked polyethylene, polyurethane, and silicone rubber as encapsulation. 3D printing technology offers a more efficient and cost-effective solution, producing intricate elements without cutting and casting. Research shows that 3D printed materials have comparable properties to polymer-based insulation, but further testing is needed to evaluate their resistance to harsh environmental conditions. This research investigates the arc resistance properties of 3D printed insulation materials for outdoor high-voltage applications, assessing their suitability for outdoor applications. The wet and dry arc resistance tests were performed in accordance with ASTM D495-99 and IEC-60587. The present work investigated three varieties of samples: polylactic acid, epoxy resin, and silicone rubber. The results of the tests reveal that polylactic acid test samples have average wet and dry arc resistance times of 2.5 hours and 1.4 seconds, which is less than silicone rubber and epoxy resin. Additional research is required to comprehend the behavior of arc formation in polylactic acid insulation materials for high-voltage 3D printing applications.

Arc erosion behaviors of the densified Ag-SnO2 contact materials containing sub-micron and nano In2O3 additives

The effects of In2O3 additive size on the physical properties and arc erosion behaviors of the densified Ag-SnO2 materials were investigated. Arc resistance mechanism was analyzed based on the microscopic morphology characterization. Results revealed that the physical properties of the Ag-SnO2(In2O3) materials were significantly improved after densification. Relative density and electrical conductivity of the materials reached above 99.5% and 71%IACS, respectively. The densified Ag-SnO2 material containing sub-micron In2O3 showed the low and stable break arc energy. The mass loss of the cathode was dramatically decreased by 65.4%. Importantly, the generation of pores and micro-cracks on the surface of electrodes were significantly restrained and the contact resistance became more stable. By comparison, the nano In2O3 additive less than 100 nm effectively suppressed not only the splash of molten Ag on the surface of cathode but also the aggregation of SnO2 particles on anode. The arc erosion products were obviously decreased, resulting in an enhancement of arc-erosion resistance of Ag-SnO2(nano In2O3) materials. Compared with that without additive, the mass loss of the Ag-SnO2 material which contains nano In2O3 obviously decreased from 2.3 to 1.4 mg. The optimal mass fraction of nano In2O3 in the Ag-SnO2 contact materials was 1 wt%.

A proposed method for calculating the voltage and current distributions of grounded and isolated networks subjected to line‐to‐ground faults

AbstractOne crucial objective of this article is to present simplified and accurate approaches to study the current distribution and ground surface potential around the area surrounding an earthed and isolated system in case of a line‐to‐earth fault. The present study is done in the case of uniform and two‐layer soils. Suggested models for calculating the distribution of the earth's surface current density, step, and touch voltages in grounded and isolated systems are presented, discussed, and adapted. The contact and arc resistances of line to ground faulty conductors are considered. Rods and/or grounding grids usually do grounded systems. The impact of both step and touch potentials and current density are investigated in this article. The methods of the calculations are based on the electrical concepts, the charge simulation method, and the imaging procedure for the grounding system. The suggested method can be considered a novel and simple technique for calculating the current distributions of the ground surface during line to ground fault. The results agree with those obtained by others, with the advantage of the proposed algorithm for its ease of application and simplicity. 3‐D dimensions’ contours of the current density and the electric potential on the earth surface around the faulty point are presented in case of homogeneous and two layers’ soil. Finally, this article's novelty is to devise a method for calculating the step and touch potentials and current density around the point of contact of the conductor carrying the electric voltages in the event of faults occurring in the electrical network, whether the network is grounded or isolated. Such faults of electrical networks may cause human hazards.

Effect of BN or B4C content on physical and tribological properties of copper‐clad laminates reinforced with carbon fiber and epoxy resin

AbstractPlasma treatment was used to improve the surface roughness of copper foil. The copper‐clad laminates reinforced with carbon fiber, boron nitride (BN), or boron carbide (B4C), and epoxy resin were prepared by hot pressing. The effect of BN or B4C content on the physical properties and tribological properties of copper‐clad laminates reinforced with carbon fiber and epoxy resin were studied. The resulting copper‐clad laminate exhibited desirable properties, such as dielectric constant, peel strength, oxygen index, and arc resistance, which were influenced by the concentration of BN or B4C particles. Additionally, the wear and friction properties of the laminate were evaluated, revealing the effects of load, sliding speed, and particle content on weight loss, specific wear rate, and coefficient of friction. SEM analysis of worn surfaces provided insight into the stages of wear, highlighting the importance of an oxide layer in reducing wear and protecting the copper surface.

Molecular dynamics simulation and performance analysis of polyimide/aramid blends.

Polyimide (PI) and aramid, as functional polymer materials, have significant application prospects in special fields such as fire prevention and arc resistance. Blends of materials can not only improve the physical and chemical properties of a single material, but also save costs, so in order to improve the performance of polyimide, it is of great practical importance to study the properties of PI and aramid blends. Molecular dynamics simulation results showed that the two materials are compatible. The solubility parameters of PI tend to stabilize when the polymerization degree exceeded 10; aramid-1313 and aramid-1414 tend to stabilize at polymerization degrees of 10 and 15 or more, respectively. On this basis, the binding energy, diffusion coefficient, and mechanical properties of PI/aramid-1313 and PI/aramid-1414 blends with different mass ratios were analyzed. It was found that with the continuous increase of aramid content, the binding energy of the blends continue to improve, limiting the gas molecules diffusion ability. The mechanical properties of the materials also continue to improve. The simulation results provided in this paper can provide theoretical guidance for experiments on PI blends and shorten the research time and cost. To investigate the properties of PI and aramid blends, the PI/aramid composite system models were constructed using the Amorphous Cell module in Materials Studio software. Subsequently, molecular dynamics simulations of the PI/aramid composite system were performed using the Forcite module, while the interactions between atoms and molecules were described using the COMPASS II force field.

Heat Resistance of Vacuum Arc Deposited TiAl Coatings on VTI-4 Alloy

Heat Resistance of Vacuum Arc Deposited TiAl Coatings on VTI-4 Alloy

Role of complex nonmetallic inclusions on the localized corrosion resistance of wire arc additively manufactured super duplex stainless steel

This study investigated the correlation between the MnS·xMnO·yAl2O3·zSiO2·TiN complex inclusions and localized corrosion initiation of the wire arc additively manufactured (WAAMed) super duplex stainless steel (SDSS) part. The results showed that partial dissolution of crystalline MnS within the complex inclusions generated an acidic aggressive environment to led the dissolution of amorphous oxides part, thereby triggering the process of localized corrosion. Additionally, micro-crevices between the inclusions and metallic matrix exacerbated localized corrosion. Finally, the catalytic-occluded cells accelerated propagation of pits. Hence, formation of high density of inclusions resulted in the poor localized corrosion resistance and repassivation ability of the as-built WAAMed SDSS.

The scale inhibition mechanism of sodium humate on heat transfer surface: Insights from electrochemical experiments, quantum chemical calculations, and molecular dynamics simulation

The scale inhibition mechanism of sodium humate (HAS) on Calcium Carbinate (CaCO3) was investigated by experiments, quantum chemical calculations and molecular dynamics simulations. The changes of electrochemical impedance spectroscopy were analyzed by electrochemical methods at different concentrations (0, 10, 30, 50, 70, 100 mg/L) of HAS. The molecular structure of HAS was optimized by quantum chemical calculation, and the charge distribution, electrostatic potential distribution and frontier orbital energy of HAS were obtained. The interaction simulation system between HAS and the crystal planes of calcite was constructed based on molecular dynamics simulation. The interaction mechanism between specific functional groups in HAS and calcite crystal plane was analyzed. The results show that the capacitance arc and charge transfer resistance increase with the increase of HAS concentration in the range of 0–50 mg. However, In the concentration range of 50–100 mg, the capacitance arc and charge transfer resistance decrease with the increase of concentration. In the optimized structure of HAS, the oxygen atom on the carboxyl group is more negatively charged. There is a strong mutual attraction between HAS and calcite crystal plane. The primary functional group responsible for achieving scale inhibition is formed through the bonding between the carboxyl oxygen atom within its molecular structure and the calcium atom on the calcite crystal plane. The research in this paper provides a strong guidance for the treatment of scale and the development of scale inhibitors.

Comparison of a Dynamic Model of Electric Arc Furnace with Actual Operation Data for Voltage Flicker Analysis in Electrical Power Network

Electric arc furnaces (EAFs) used in the iron and steel manufacturing industry for melting and refining scrap metals are one of the most disturbing loads that exhibit unbalanced and highly nonlinear characteristics. Serious voltage fluctuations occur in the power system as a result of the rapid change in the current drawn from the grid by the EAF. Voltage fluctuations lead to a power quality problem known as flicker, which is defined as observable changes in light sources that affect the production environment, cause eye fatigue in personnel, and lower the work concentration levels. To investigate the voltage flicker problem, an accurate mathematical model describing the behavior of the EAF load is required. In this study, a dynamic EAF model that can be adjusted to different operating conditions has been developed in the time domain. The electric arc voltage has been modeled as an externally controllable voltage source. The instantaneous arc voltage has been expressed as a function of the arc length independent of the current. The arc resistance, which varies with time and is nonlinear, has also been calculated with differential equations using the instantaneous arc voltage value. To measure the short-term flicker severity index caused by the EAF in the power system, a flicker meter in compliance with the International Electrotechnical Commission (IEC) 61000-4-15 standard has been designed. The current-voltage characteristics of the EAF, its effect on the power system, and the flicker severity occurring at the point of common coupling (PCC) have been analyzed with simulation studies using the PSCAD/EMTDC software. Besides, the simulation results of the dynamic model of the EAF have been compared with the results obtained from the model based on the measured field data.

DC Arc Quenching Using Ablation of Polymer Narrow‐Section Arranged around Fuse Element

This paper was arranged a polymer cylinder around a Cu fuse‐element to increase both an arc resistance during a DC arc quenching process and an insulation resistance after the DC arc quenching. The used polymer cylinder equips a narrow‐section with a width made from the polymer. A position of the narrow‐section was around an arc‐ignition point of the Cu fuse‐element. Silica‐sand (SiO2‐sand) was filled inside the polymer cylinder. Then, a damping DC with a prospective peak of 1000 A was energized to the Cu fuse‐element. As an experimental result, was successfully increased with of the narrow‐section. In addition, the rise in of the narrow‐section also increased to more than 10 under the DC 1000 V application after the arc quenching. In order to interpret rise and high under the polymer cylinder arrangement, chemical composition, an electrical resistivity , and a thermal diffusivity of Cu/SiO2/Polymer vapor mixture was also calculated. Based on the experimental result and calculation result, rise can be interpreted based on rise in and due to the polymer vapor admixing into Cu/SiO2 vapor mixture. In addition, increasing can also be interpreted by the polymer ablation of the narrow‐section of the cylinder. The results are useful to further increase the interruption capacity of the DC fuse. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.