Arc Erosion Research Articles

Surface Average Temperature Measurement of Cu-W Contact Material Burning in CO2: Preliminary Study

The surface average temperature and the electrode temperature distribution are key parameters to predict the electrode erosion. Experimental research on the arc erosion has been carried out in a model circuit breaker, in which CO2 is filled in the chamber and Cu-W is used as the contact material. The surface average temperatures of plug contact exposed to electric arc with sinusoidal currents of 5kA were determined by a high-speed pyroscope. In order to establish a relationship between the average temperature of the contact surface and current squared, the data statistics and fitting curves in the current-rising and current-falling stages were given. It has been found that there are two different types of arc erosion processes by comparing the temperature-current squared curves. In other words, the structure of contact surface and the electrode material change significantly after repeated arc erosions.

Experimental Study of Arc Erosion in Gas-blasting and Free-burning Conditions in High-voltage Circuit Breakers

Arc erosion behavior depends on varieties of factors, such as the shape and material of contacts, the gas type and the pressure filled in the chamber. In this contribution, experimental research on the gas-blasting and free-burning conditions was carried out in a model circuit breaker to investigate the gas blowing effect on the mass loss of arcing contacts. SF6 was filled in the chamber and copper-tungsten was used as the contact material. Three different peak current amplitudes (5/20/35kA) were selected, and the average mass loss of plug contact was measured after five consecutive arcing tests. The erosion physical process between arc root and contact material is extremely complex. The mass loss was estimated with four different indexes, which include integral of current squared, thermal stress, transferred electric charge and arc energy. It has been found that the arc energy can be used to represent the degree of arc erosion to relate the gas-blasting and free-burning conditions.

Effect of Y on Arc Breaking Behavior of Platinum–Iridium Alloy Contact Materials at Different Voltages

The Pt–Ir alloy is an important electrical contact material in the aerospace field, and its electrical contact performance directly affects the reliability and stability of the circuit system. In order to elucidate the effect of Y on the breaking arc behavior of Pt–Ir alloys at different voltages, Pt-10Ir-1Y and Pt-25Ir-1Y alloys were prepared using melting and thermal processing, and the electrical contact tests were carried out at DC 15 A 12 V, 24 V, and 36 V. When comparing the results of Pt-10Ir and Pt-25Ir electrical contact tests, they showed that Y doping provided a tendency to concentrate individual arc erosion regions. Meanwhile, the comparative study showed that the addition of Y could inhibit the tendency of the Pt–Ir arc time to increase with voltage. At 36 V, the overall arc time of Pt–Ir–Y was significantly lower than that of Pt–Ir, and the fluctuation in arc time and arc energy was reduced. In addition, Y reduced the welding force of Pt–Ir alloys at 12 V, while Y improved the stability of the welding force of Pt–Ir alloys at 24 V. It could be seen that Y was favorable to improving the arc erosion resistance of the Pt–Ir alloy under certain conditions. The contact resistance analysis showed that there was an obvious partitioning phenomenon in the contact resistance of Pt–Ir alloys, and Y changed in this phenomenon at a certain voltage range. In addition, the material transfer direction of the Pt–Ir alloy was from the anode to the cathode, which was not affected by the voltage change, while the addition of Y changed the material transfer direction from the cathode to the anode, which was likely caused by the change from the metal-phase arc dominance to gas-phase arc dominance.

Influence of service parameters on the current-carrying tribological properties of CF-Al2O3/Cu composites

PurposeThe effect of different service parameters on the current-carrying tribological properties of CF-Al2O3/Cu composites was investigated, and the damage behavior of the composites under different service parameters was probed. The purpose of this study is to provide a theoretical basis for the application of CF-Al2O3/Cu composites.Design/methodology/approachThe composites were fabricated by internal oxidation combined with powder metallurgy. The current-carrying tribological properties of CF-Al2O3/Cu composites were investigated on an electrical damage test system at different loads and currents.FindingsAs the load increases, the wear mechanism of the composite changes from abrasive wear to delamination wear. As the current increases, the oxidation wear and arc erosion of the composites gradually intensified. Under the service parameters of 0–25 A and 30–40 N, the composite has relatively stable current-carrying tribological properties.Originality/valueThis paper could provide a theoretical basis for the practical application of CF-Al2O3/Cu composites.

Arc Erosion Properties of WCu Material Reinforced with Ti3SiC2under Different Applied Voltages

Introducing reinforcements is a crucial way to modify WCu electric contacts. Herein, the arc erosion performances of WCu/Ti3SiC2under various direct current voltages are investigated. The eroded microstructures are observed by a 3D laser scanning confocal microscopy and a thermal field emission scanning electron microscope. Compositions of the eroded surfaces are analyzed by a Raman spectroscopy. With the elevated voltages, values of breakdown current, arc duration, arc energy, and arc discharge distance increase, while the breakdown strength decreases. Meanwhile, the eroded regions gradually change from circular shape to irregularly curved corrugations under the elevated voltages. Copper and Ti3SiC2can disperse arc during arc discharge, and the liquid and gas generated by the two phases can make differences in protecting WCu/Ti3SiC2.

Failure analysis of the pure carbon strip affected by dynamic contact force during current-carrying sliding

The pure carbon strip is widely used in high-speed Electro Mechanical Units (EMUs) transit. Dynamic contact between the pantograph and the catenary produces internal cracks in the pure carbon strip, which results in the break of the pantograph and interruption of power transmission. The tribological properties and failure mechanism of the pure carbon strip is studied in this paper. The current-carrying tribology experiments were carried out on a flexible loading test rig. It is found that the dynamic contact in pantograph/catenary system produces regular influence on arc discharge and current transmission. The cracks and arc erosion are the most important failure mechanisms subjected to the periodic vertical contact force. The carbon fibers in the strip became orderly arranged honeycomb-structures after oxidation and sublimation. These honeycomb-structures distributed nearby the pores and induced the initiation and propagation of cracks. Therefore, preparing high-strength carbon fibers and eliminating the combination gap between the carbon fibers and the carbon matrix are recommended to prevent the failure of pure carbon strip. Results in this paper are expected to provide data support for the failure analysis and manufacturing technology to the pure carbon strip, as well as providing theoretical supports to the locomotives in service.

Enhancement mechanism of carbon fiber on the current-carrying tribological properties of Cf-Al2O3/Cu composites

Cf-Al2O3/Cu composites were fabricated by powder metallurgy combined with internal oxidation. The microstructure, electrical contact properties and tribological properties of the fabricated composites were characterized. The results showed that the addition of an appropriate amount of carbon fibers improved the tribological properties of Al2O3/Cu composites. The friction coefficient of the composites is lower (0.182) and the specific wear rate decreased by 64.2% in comparison with Al2O3/Cu composites. The reduction of arc erosion reduced the roughness of the friction surface of the composite and improved the stability of the friction system. And the improvement of friction stability, in turn, avoided the formation of bumps and pits on the friction surface and prevented concentrated arc erosion at the bumps.

Study on arc duration and erosion characteristics of cable electrodes in AC series circuits

Arc duration and erosion characteristics of cables are closely related to electrical fire hazards. In this study, the arc duration and arc erosion characteristics of copper and aluminum core cables were explored. The main erosion modes of copper core cable with mica insulation (HC0) and aluminum core cable with polyimide (PI) insulation (HA0) were determined. Results show that several large molten droplets with diameters of 5 ± 0.5 mm would drip down from the molten pool on the cable end during arcing of HC0, but the molten droplets are adhered to the molten pool and do not drip down during arcing of HA0. We concluded that the differences in melting energy and oxide film between copper and aluminum are the main reasons for this phenomenon. Besides, the molten pool can be formed on the cable end as the insulation is heatproof, which plays a vital role in prolonging the arc duration of cables. The arc duration of cables with heatproof insulation is longer than those with common insulation. This means that the cables with heatproof insulation have higher fire hazards from the perspective of arc duration. To further understand the influence of molten pools on arc duration, an arc duration model was developed based on energy balance, which is beneficial in determining the arc duration of cables with heatproof insulation in electrical fire accident investigation.

Comparative study of the microstructure and arc erosion resistance of Ag/Ti2AlX (X = C, N) electrical contact materials

A group of MAX phases including Ti2AlC and Ti2AlN, are candidate reinforcements of Ag-based electrical contact materials. In this work, the interfacial reaction, resistivity, hardness and arc erosion resistance of Ag/Ti2AlX (X = C, N) were investigated comparatively. During the sintering of both Ag/Ti2AlX, Al deintercalated from Ti2AlX and Ag diffused into Ti2AlX. The interfacial reaction was mild in Ag/Ti2AlN while obvious in Ag/Ti2AlC. The first-principles calculation indicated that the higher vacancy formation energy of Al in Ti2AlN led to the mild reaction in Ag/Ti2AlN, which then resulted in a larger decrease in hardness and resistivity, as compared with Ag/Ti2AlC. Moreover, Ag/Ti2AlN showed superior arc erosion resistance, with less evaporation of Ag and oxidation of Ti2AlC. This were attributed to the lower vulnerability of mildly decomposed Ti2AlN, less resistance heat and easier heat dissipation, resulting from the superior electrical and thermal conductivity.

Arc Erosion Behaviors and Surface Characteristics of SnO2 Nanofiber/Particle Reinforced Ag-Based Composite

Arc Erosion Behaviors and Surface Characteristics of SnO2 Nanofiber/Particle Reinforced Ag-Based Composite

First-principles and experimental investigations on physical properties and arc erosion behavior of metal-doped AgSnO2 electrical contact materials

The effects of metal doping on the structural and physical properties of AgSnO2 contactors were investigated using simulations and experiments based on first-principles calculations. The electrical contact test system was tested for 20,000 electrical contacts to check the physical properties under 24 V/15 A DC resistive load and analyze the relationship between the parameters. The erosion morphology of the contact material was characterized by a 3D surface profilometer, and the mechanism of the molten pool force, material transfer, and arc erosion behavior was studied in detail. The results show that metal doping can improve the thermal stability, mechanical properties and electrical conductivity of the materials, and significantly affect the crystalline and electronic structure of the materials, resulting in better stability and resistance to arc erosion. The best arc erosion performance of AgSnO2–Y is related to its superior thermal stability and electrical properties, while the better arc erosion performance of AgSnO2–Cu is probably related to its good mechanical properties. In addition, metal doping has a significant effect on the arc formation and interruption of AgSnO2 contactors and leads to a change in the material transfer mode. This study provides a feasible method for the analysis of metal doping to improve the erosion performance of contact materials and provides a valuable reference for the further development of research on arc erosion resistance of contactors.

A new TiBN conductive ceramic powder and its application in copper-based electrical contact materials

In this paper, a new TiBN micro-nano powder was synthesized by boronizing sintering method. The TiBN powder exhibits specific micro-nano composite structure, which is composed of TiBN crystal and amorphous layer of nanometer size. The amorphous structure mostly distributes along particle boundary with minimum thickness of 2 nm. The TiBN powder shows combined ceramic and metallic properties with an exordinary electrical conductivity, having an electrical resistivity of 2.655 × 10−5 Ωm (much better than that of TiN, TiCN, TiB2 and TiC). Solid dissolution of B into TiN decreases the number electron of the system and pull down the Fermi level, making the electron present a quasi-linear dispersion contributing to excellent electrical conductivity of TiBN powder. Such TiBN can be used as conductive phase and reinforcing phase in electrical contact materials. Additionally, the TiBN significantly improve the arc erosion resistance of copper-based electrical contact without reducing the electrical conductivity of copper. When the reinforced phase content was 2.5 wt%, the resistivity of Cu/TiBN was 0.26 × 10−6 Ωm, which was only 20.5% that of Cu/TiN. TiO2, Ti3O5, B2O3 and N2 were formed on the surface of Cu/TiBN samples during arc erosion. Such products can significantly enhance the arc erosion resistance of Cu/TiBN electrical contact materials. This TiBN powder synthesis route can be used to prepare bulk materials in engineering materials industry. In addition, it has attractive research value and broad application prospects in photovoltaic cells and energy storage collector applications including lithium batteries, supercapacitors, and fuel cells.

Fabrication and Arc Erosion Behavior of Ag-SnO2-ZnO Electrical Contact Materials.

This study investigated the synthesis of Ag-SnO2-ZnO by powder metallurgy methods and their subsequent electrical contact behavior. The pieces of Ag-SnO2-ZnO were prepared by ball milling and hot pressing. The arc erosion behavior of the material was evaluated using homemade equipment. The microstructure and phase evolution of the materials were investigated through X-ray diffraction, energy-dispersive spectroscopy and scanning electron microscopy. The results showed that, although the mass loss of the Ag-SnO2-ZnO composite (9.08 mg) during the electrical contact test was higher than that of the commercial Ag-CdO (1.42 mg), its electrical conductivity remained constant (26.9 ± 1.5% IACS). This fact would be related to the reaction of Zn2SnO4's formation on the material's surface via electric arc. This reaction would play an important role in controlling the surface segregation and subsequent loss of electrical conductivity of this type of composite, thus enabling the development of a new electrical contact material to replace the non-environmentally friendly Ag-CdO composite.

Arc erosion resistance of WC/CuCr30 composites based on changing of Cr particle morphology and orientation

CuCr30 composite was commonly applied in medium and low voltage vacuum interrupters. The WC/CuCr30 composites based on changing of Cr particle morphology and orientation were successfully prepared by vacuum hot press sintering and hot extrusion, and the arc erosion resistance behavior at different voltages along the deformation direction of Cr particles was investigated on the JF04C electrical contact material testing system. The microstructure characterization of WC/CuCr30 composites shows that the Cr particles in the WC/CuCr30 composite have been elongated and the long axis direction is close to parallel to the extrusion direction after the hot extrusion deformation. Compared with the longitudinal section, the thermal conductivity of CuCr30 and WC/CuCr30 composites in the cross section is increases by 3.75% and 3.63%, respectively. The electrical contact testing results under different voltages shows that the addition of WC particles can extend the service life of the CuCr30 composite, and the operation times of WC/CuCr30 composite (4850 times) increases by 34.72% compared to CuCr30 composite (3600 times) at 30 V DC. The welding force decreases more obviously with the increase of the voltage, and the average welding force of WC/CuCr30 composite decreases by 8.57% and 20.9% at 24 V DC and 30 V DC compared with CuCr30, respectively. The arc erosion mechanism analysis shows that addition of WC particles is beneficial for the decrease of arc duration. And WC particles can effectively inhibit the arc erosion process and delay the formation of bumps and pits.

A Theory of Slope Shear Scouring and the Failure Mechanism of PFC3D on a Gangue Slope

In this paper, scouring shear failure theory is optimized based on the gangue slope near the thermal power field in Baiguo Town, Panzhou City, Guizhou Province. Based on the particle flow PFC (particle flow code) 3D fluid–solid coupling method, the scouring failure mechanism of ditch no. 5 of the gangue slope is comprehensively analyzed from the perspectives of the failure mode, displacement, motion track, and stress–strain. We consider the scouring shear theory in respect of (c, φ); this theory is dominated by two types of scouring intensity factors and can effectively explain the internal mechanisms of gully formation. The rainfall scouring failure of gangue slopes can be divided into four stages: (1) integral splash erosion and local pitting at the bottom of the slope; (2) erosion diversion and pitting in the slope; (3) the tributary–slope crest extension schist erosion stage; and (4) integral gully erosion and the landslide stage. The failure process is not only characterized by discontinuous failure but also occurs in the order of bottom–middle–branch–top. A three-section stepped effect is observed during the process in which the gangue is scoured and destroyed, which fully verifies the intermittent characteristics of the scouring and destruction of gangue slopes. During the whole process, the maximum displacement is concentrated at the top of the slope, and its proportions are as follows: top of the slope > tributary > middle of the slope > foot of the slope. The peak displacement of the slope crest in the horizontal Y-direction accounts for 41.76%, and that in the Z-direction accounts for 45.84%. Scouring deposits can be divided into the arc erosion deposit mode and the sector erosion deposit mode. Mainstream gullies primarily control whether deposits are characterized as arc or straight erosion deposits. The later stage of the second phase of scouring is the incubation period of the tributary gully. The large accumulation makes the stress at the bottom of the slope increase sharply, and the fluctuation value is between 2 and 6.8 MPa. The generation of the branch notch is mainly determined by X-direction stress, and 8.6 MPa is the critical stress. In efforts to prevent and control rainfall and landslide, the slope foot area should be preferentially protected, and the soil mass in the slope should be reduced to prevent the maximum energy fluctuation caused by scouring, so as to prevent significant displacement damage of the slope top.

Effect of short-time hot repressing on a Ag-SnO2 contact material containing CuO additive

It remains difficult to achieve high-density metal matrix composites by traditional powder metallurgy. In this study, short-time hot repressing was proposed to densify a Ag-SnO2 contact material prepared by powder metallurgy. The effect of the vacuum repressing temperature on the Ag-SnO2 material containing CuO additive was systematically investigated under a constant pressure of 200 MPa. The results showed that the relative density of the material repressed at 800 °C for 10 min can be increased to as high as 99.75%. The microstructure of the Ag-SnO2(CuO) material was obviously refined and homogenized by short-time hot repressing. The dispersive distribution of the SnO2 particles in the Ag matrix was induced, resulting in the elimination of particle aggregation. It is worth noting that almost all the CuO additive was decomposed into Cu2O after hot repressing, which was beneficial for improving the electrical contact properties. Furthermore, the arc energy of the repressed material significantly decreased with increasing repressing temperature, which can be attributed to the high density and uniform microstructure. During arc erosion, the mass loss of the Ag-SnO2(CuO) materials repressed at 800 °C was smallest, and the formation of pores and cracks was inhibited. However, the relative density of the material showed a tendency to decrease when the repressing temperature reached 850 °C.

Microstructure and electrical contact behavior of the nano-yttria-modified Cu-Al2O3/30Mo/3SiC composite

Abstract With the rapid development of the copper-based composite in the field of electrical contact material industry, the problem of poor arc erosion resistance of the copper-based material becomes more and more prominent. Improving the arc erosion resistance of the copper-based composite is an urgent problem to be solved. Cu-Al2O3/30Mo/3SiC and 0.5Y2O3/Cu-Al2O3/30Mo/3SiC electrical contact composites were prepared in a fast-hot-pressing sintering furnace. The microstructure and phase structure of the composites were analyzed by using a scanning electron microscope, transmission electron microscope, and X-ray diffraction meter, respectively. The arc erosion properties of the composites at 25 V, DC and 10-30 A were investigated by using a JF04C electric contact tester. The mass loss of the composites was reduced by 77.8%, and the arc erosion rate was reduced by 79.6% after the addition of nano-yttrium oxide under the experimental conditions of 25 V, DC and 30 A. At the same time, the arc energy and welding force of the composite after switching operations decreased, indicating that the addition of nano-yttria improved the arc erosion resistance of the composite. This work provides a new method for improving the arc erosion resistance of the copper-based composite contact material.

Study on magnetically blown arc characteristics and the resulting contact erosion mechanisms of high-power DC relays

High-power DC relays are widely used in new energy power systems and DC distribution networks, and commonly use transverse magnetic fields to accelerate arc extinguishing. In this paper, the magnetically blown arc characteristics and the resulting contact erosion mechanisms of high-power DC relays are studied by experiments and simulations. The experiments are carried out to analyze the arc motion, contact erosion mass, and contact morphologies, and to verify the simulation model. Considering the energy transfer source term, the establishment of a more perfect magnetohydrodynamic arc model is accomplished, and an erosion model is further established. The results indicate that the magnetically blown arcing process has three stages while the arc shapes and motion characteristics are different, and the heat flux acting on the contact can be accurately obtained by the arc model. The greater external transverse magnetic field is more conducive to extinguishing the arc and reducing the arc erosion time. In contrast, the Archimedes force plays a very small positive role and the self-induced magnetic field of the arc has a negative effect. For contact erosion, the temperature distribution of the molten pool appears trailing effect. Moreover, the advanced mathematical model proposed for erosion mass has good accuracy. The calculation results of erosion rates show that Cr reduces erosion while the current increases erosion nonlinearly. Besides, the flow and deformation characteristics of the molten pool will lead to convex strip-shaped erosion traces and arcing position transfer, and the moving erosion will cause the lateral accretion effect. Furthermore, the analysis shows that the reason for edge droplet sputtering is the pressure difference caused by Plateau–Rayleigh instability, and optimization suggestions for reducing contact erosion are given.

Simulation and Verification of Effect of Arc Duration on Arc Temperature Based on COMSOL

The pantograph–catenary arc of urban rail has the characteristic of high temperature, which directly acts on the surface of the pantograph–catenary system, will seriously ablate pantograph and contact line, and affect the flow of the pantograph–catenary system. In this paper, based on MHD, a mathematical model of the arcing of urban rail pantograph–catenary system is established. COMSOL finite element software was used to simulate the arc temperature field of the pantograph–catenary arc. Through the temperature distribution cloud diagram and related images, the relationship between the arc central temperature, the duration, and the gap of the pantograph arc were studied. It is found that the arc temperature increases with the increase in arc duration when the arc gap is fixed. When the arc duration is fixed, the arc center temperature changes inversely with the increase in the arc gap. The feasibility of the simulation model is verified by the pantograph–catenary arc experiment platform. The research conclusion of this paper can provide a certain basis for the research of arc erosion on the surface of the pantograph–catenary system.

Research on dynamic characteristics of arc under electrode relative motion

The relative motion of the electrodes is a typical feature of sliding electrical contact systems. The system fault caused by the arc is the key problem that restricts the service life of the sliding electrical contact system. In this paper, an arcing experimental platform that can accurately control the relative speed and distance of electrodes is built, and the influence of different electrode speeds and electrode distances on arc motion characteristics is explored. It is found that there are three different modes of arc root motion: single arc root motion mode, single and double arc roots alternating motion mode, and multiple arc roots motion mode. The physical process and influence mechanism of different arc root motion modes are further studied, and the corresponding relationship between arc root motion modes and electrode speed is revealed. In addition, to further explore the distribution characteristics of arc temperature and its influencing factors, an arc magnetohydrodynamic model under the relative motion of electrodes is established, and the variation law of arc temperature under the effect of different electrode speeds and electrode distances is summarized. Finally, the influence mechanism of electrode speed and electrode distance on arc temperature, arc root distance, and arc root speed is clarified. The research results enrich the research system of arc dynamic characteristics in the field of sliding electrical contact, and provide theoretical support for restraining arc erosion and improving the service life of the sliding electrical contact system.