Circuit Breaker Contacts Research Articles

Phase-Field Simulation and Dendrite Evolution Analysis of Solidification Process for Cu-W Alloy Contact Materials under Arc Ablation

Cu-W alloys are widely used in high-voltage circuit breaker contacts due to their high resistance to arc ablation, but few studies have analyzed the microstructure of Cu-W alloys under arc ablation. This study applied a phase-field model based on the phase-field model developed by Karma and co-workers to the evolution of dendrite growth in the solidification process of Cu-W alloy under arc ablation. The process of columnar dendrite evolution during solidification was simulated, and the effect of the supercooling degree and anisotropic strength on the morphology of the dendrites during solidification was analyzed. The results show that the solid–liquid interface becomes unstable with the release of latent heat, and competitive growth between dendrites occurs with a large amount of solute discharge. In addition, when the supercooling degree is 289 K, the interface is located at a lower height of only 15 μm, and the growth rate is slow. At high anisotropy, the side branches of the dendrites are more fully developed and tertiary dendritic arms appear, leading to a decrease in the alloy’s relative density and poorer ablation resistance. In contrast, the main dendrites are more developed under high supercooling, which improves the density and ablation resistance of the material. The results in this paper may provide a novel way to study the microstructure evolution and material property changes in Cu-W alloys under the high temperature of the arc for high-voltage circuit breaker contacts.

Microwave Hybrid Sintering and Soldering of Cu-Cr-W Composite Material for Reactive Power Breakers.

Over 60% of reported failures for reactive power compensation systems are given for damage to electrical circuit breaker contacts. This paper presents a study on the development of microwave technology for sintering of W-Cu-Cr alloys at 1012 °C for 65 min using 623.38 W microwave power, as well as microwave joining at 231 °C of the W-Cu-Cr composite material on body contact using 475 W microwave power for 55 s. The joined components were subjected to mechanical and electrical tests in accordance with ICE standards to validate the applied technology. Tests of connection-disconnection of the electrical contacts were carried out in accordance with the maximum number of disconnections allowed by the manufacturer (2 cycles/min): 25 s rest time and 5 s operating time under load. The components of the electrical contact after 111237 switches were analyzed under a microscope revealing a reduction of the damaged area by 27% compared with the original contact.

Analysis of electric repulsion on contacts of different molded case circuit breakers

Analysis of electric repulsion on contacts of different molded case circuit breakers

First‐Principles Calculations of Material Properties of CuCrZr Alloy Contacts

CuCrZr alloy is widely used in vacuum circuit breaker contact materials and high‐speed railroad contact wires, etc. The study of the effect of different Cr and Zr contents on the performance of CuCrZr alloy is of great significance for the improvement of circuit breaker's breaking capacity, as well as the load and structural stability under harsh working conditions. In this paper, the mechanical properties, electronic density of states and thermodynamic properties of CuCrZr solid solution alloys randomly doped by different concentrations of Cr and Zr are comparatively analyzed using first‐principles calculations based on density functional theory. The results show that the alloys with different doping compositions have strong mechanical stability, electrical conductivity, and thermomechanical stability, and the reduction of the Cr/Zr doping concentration ratio can improve the toughness and ductility of the alloys, and the solid solution alloy with the composition of CuCr0.06Zr0.19 has the best machinability. The doping of Cr and Zr can improve the thermal stability of the alloy, Cr and Zr can be used as high‐temperature toughening elements for Cu. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Methodology for Circuit Breaker Contact Diagnosis through Dynamic Resistance Measurements and Fuzzy-Logic-Based Analysis

This paper presents a methodology capable of measuring, processing, and extracting contact resistance parameters that enable the identification of the contact degradation level inside arc extinction chambers in medium- and high-voltage circuit breakers (CB). To determine the contact degradation level, an algorithm was developed to extract the characteristic parameters from the results of dynamic resistance measurement (DRM). To analyze the dataset parameters, this work employs the combination of different statistical tools, such as boxplots and fuzzy logic, enabling the evaluation to be conducted without the subjectivity inherent in human decision. Therefore, a more objective and reliable diagnosis could be achieved. The DRM tests were performed on two types of minimum-oil CB (MOCB), 800 A/15 kV/12.5 kA (CB-A) and 2000 A/72.5 kV/31.5 kA (CB-B and CB-C). For CB-A and CB-B, three contacts were utilized for each CB, with significant contact degradation. For CB-C, a single contact was employed without significant degradation. The DRM curves of the CB-C contact were used as the reference for evaluation of the CB-B contacts. For this purpose, a new DRM system was developed. The proposed methodology can be defined as a complement for other diagnostic techniques, serving as a non-subjective asset management tool, supporting decisions regarding equipment interventions.

Application of DE-ELM Algorithm in SF6 Circuit Breaker Contact Ablation Evaluation

When assessing the ablation status of circuit breaker contacts, the average dynamic contact resistance of the arc contacts of high-voltage SF6 circuit breakers is crucial. The average dynamic contact resistance of arc contacts on circuit breakers under various current levels may be accurately predicted using a method based on a differential evolution algorithm and extreme learning machine (DE-ELM), which is suggested in this research. Combining optimization algorithms yields the ideal input weight and hidden layer bias of the ELM method. The DE-ELM approach has outstanding anticipation performance for anticipation data under various current levels when compared to other anticipation methods. Finally, an expert system for assessing the ablation state of contacts based on the DE-ELM algorithm is created using the average dynamic contact resistance data of arc contacts predicted by DE-ELM. As a guide for the upkeep of high-voltage SF6 circuit breakers, the ablation status of contacts is categorized into four grades: A-level ablation, B-level ablation, C-level ablation, and D-level ablation.

Electrical Erosion Resistance of Graphene Reinforced Cu-W Circuit Breaker Contact Materials under 5 kA Arc

This work integrates experimental and MD simulation approaches to study the role of graphene in G-Cu-W composites. Arcing tests were conducted on G-Cu-W and Cu-W contact samples under a 5kA peak current. Experimental results show that adding graphene leads to a lower surface roughness of the sample following arcing. MD simulation results indicate that the G-Cu-W model exhibits a smoother surface and fewer lost metal atoms than the Cu-W model due to the protective effect of graphene layer.

Fluid-chemical modeling of the near-cathode sheath formation process in a high current broken in DC air circuit breaker

When the contacts of a medium-voltage DC air circuit breaker (DCCB) are separated, the energy distribution of the arc is determined by the formation process of the near-electrode sheath. Therefore, the voltage drop through the near-electrode sheath is an important means to build up the arc voltage, which directly determines the current-limiting performance of the DCCB. A numerical model to describe the near-electrode sheath formation process can provide insight into the physical mechanism of the arc formation, and thus provide a method for arc energy regulation. In this work, we establish a two-dimensional axisymmetric time-varying model of a medium-voltage DCCB arc when interrupted by high current based on a fluid-chemical model involving 16 kinds of species and 46 collision reactions. The transient distributions of electron number density, positive and negative ion number density, net space charge density, axial electric field, axial potential between electrodes, and near-cathode sheath are obtained from the numerical model. The computational results show that the electron density in the arc column increases, then decreases, and then stabilizes during the near-cathode sheath formation process, and the arc column’s diameter gradually becomes wider. The 11.14 V–12.33 V drops along the 17 μm space charge layer away from the cathode (65.5 kV/m–72.5 kV/m) when the current varies from 20 kA–80 kA. The homogeneous external magnetic field has little effect on the distribution of particles in the near-cathode sheath core, but the electron number density at the near-cathode sheath periphery can increase as the magnetic field increases and the homogeneous external magnetic field will lead to arc diffusion. The validity of the numerical model can be proven by comparison with the experiment.

SF6 High-Voltage Circuit Breaker Contact Status Detection at Different Currents.

Currently, the online non-destructive testing (NDT) methods to measure the contact states of high-voltage circuit breakers (HVCBs) with SF6 gas as a quenching medium are lacking. This paper aims to put forward a novel method to detect the contact state of an HVCB based on the vibrational signal. First, for a 40.5-kV SF6 HVCB prototype, a mechanical vibration detection system along with a high-current generator to provide the test current is designed. Given this, vibration test experiments are carried out, and the vibration signal data under various currents and corresponding contact states are obtained. Afterward, a feature extraction method based on the frequency is designed. The state of the HVCB contacts is then determined using optimized deep neural networks (DNNs) along with the method of adaptive moment estimation (Adam) on the obtained experimental data. Finally, the hyperparameters for the DNNs are tuned using the Bayesian optimization (BO) technique, and a global HVCB contact state recognition model at various currents is proposed. The obtained results clearly depict that the proposed recognition model can accurately identify five various contact states of HVCBs for the currents between 1000 A and 3500 A, and the recognition accuracy rate is above 96%. The designed experimental and theoretical analysis in our study will provide the references for future monitoring and diagnosis of faults in HVCBs.

Interpretation of NSDD and Restrike in Capacitive Current Switching Test on Medium Voltage Vacuum Circuit Breaker

Capacitor banks are installed in an increasing number to control power quality issues and improving the power factor tocounteract the reactive power in the transmission and distribution networks. Due to load fluctuations switching of capacitorbanks is a typical phenomenon. Capacitor bank is normally having concentrated capacitance in contrast with distributedcapacitance. It generally draws more current than unloaded cableor line in practical cases up to several hundred amperes.Hence, switching of capacitor bank causes a very high rate of rise of transient recovery voltage across circuit breakercontacts. This scenario can be simulated in testing laboratories by a voltage source connected to a circuit breaker whichagain is connected to a large capacitance in terms of IEC called capacitive current switching test. Non-sustained disruptivedischarge (NSDD) is a voltage breakdown after the vacuum circuit-breaker open the fault current which will not cause therecovery of power frequency current. Restrike is different from NSDD, the recovery of power frequency current betweenthe contacts will make the breaker failed. It’s not easy to show the distinction between NSDD and restrike during some typetests. The paper presents the study of performance evaluation of the circuit breaker during the capacitor current switchingduties. A statistical analysis of failure of circuit breaker during capacitor current switching tests are included in the paperto help the manufacturers & utilities, so that the care can be taken for trouble free services. The paper also discusses thechanges made in the IEC 62271 – 100, Amendment1:2012 for conducting the capacitive current switching tests.

저압직류차단기의 소전류 영역 차단특성과 성능향상을 위한 연구

A low voltage direct current(DC) circuit breaker is an electrical protection device that interrupts the abnormal fault currents which result from the over-loads or short-circuits in a low voltage(less than 1,500Vdc) power distribution line. Recently, as interests in renewable energy fields(such as photovoltaic and energy storage systems) have increased, research on DC circuit breakers for system protection is also being actively conducted. However, breaking the fault current in DC system is considerably difficult even small current region since the DC does not have current zero point such as in AC. When a short circuit occurs, a fault current flows between contacts of a DC circuit breaker even though they are separated by the protective control system. Arc voltage between contacts of the circuit breaker should generate as high as possible during breaking phase. High arc voltage could lead the fault current of the circuit to zero so that arc plasma is eliminated. Based on this behavior, arc extinction system of a DC circuit breaker should be designed to effectively increase the arc voltage during current interruption period. In this paper, the characteristics of DC breaking specially in small current region were confirmed through several types of current breaking experiments and result analysis, and a method to improve performance of DC breaking in small current region was presented, and experiments were carried out to verify the validity of the method.

Ablation state assessment of SF6 circuit breaker contacts based on BP neural network and mean impact value

In order to evaluate the ablation state of the SF6 circuit breaker contacts, simulated ablation tests were carried out on the circuit breaker, and the dynamic resistance curve as a function of contact travel was measured with three levels of injected current. The results showed that the increasing of test current value can reduce the fluctuation of the dynamic resistance curve as a function of contact travel. In addition to the ablation effect of current, the loosening of the operating mechanism will affect the accuracy of opening and closing action of the contact, resulting in the continuous reduction of the main contact travel in the dynamic resistance curve as a function of contact travel. Based on the measurement results, a BP neural network evaluation model was built to evaluate the ablation state of the contact. Seven parameters were extracted from the dynamic resistance curve as a function of contact travel as model inputs, and mean impact value algorithm was used to optimize the model. After the optimization, the average relative error of the evaluation to the verification set is less than 10.4%.

High anti-arc erosion performance of the Al2O3 reinforced Cu@W composites for high voltage circuit-breaker contacts

High voltage circuit-breakers with superior performance are demanded as the transmission distance extends and voltage rises, which are often subject to high current and voltage surges. Commercial circuit-breaker contacts are conventionally manufactured with CuW alloy by infiltration method, limiting their performance improvement in withstanding current (or voltage) and lifespan. In this paper, we optimize the microstructure and component of Al2O3 reinforced Cu@W80 composites (Al2O3/Cu@W80), which fabricates the Cu@W powder first by chemical coating and the composites by spark plasma sintering (SPS) method. The composites exhibit enhanced hardness (maximum value up to 273 HV) due to the addition of Al2O3 powder and a more homogeneous and refined tungsten phase compared to the CuW counterpart. Moreover, the dispersed Al2O3 particles with low work function become the preferred ablation phase and guide the electrical arcs, further improving the anti-arc erosion performance of Al2O3/Cu@W80. Our findings suggest that the Al2O3/Cu@W80 composite with optimized components could be potentially used as a candidate for high-voltage circuit-breaker contacts.

A Novel Control Strategy of Phase-Controlled Switching Technology for Vacuum Circuit Breaker

The opening and closing of a vacuum circuit breaker in the selected phase of the system voltage and the associated electrical equipment plug in or disconnect the electrical system with minimal impact on itself and the system. To realize this and ensure the control precision and stability of its action process, this study designs the drive motor and controller of a vacuum circuit breaker actuator. Additionally, a new function-switching pseudo-differential control (FPD) strategy is based on the feedback element principle. The control strategy avoids the direct differentiation of the controlled variables and has the ability of a fast dynamic response and anti-interference. At the same time, according to the moving process of the circuit breaker contacts, the control parameters are directly assigned to the system in stages, which reduces the amount of calculation and enhances the response speed of the control system. According to the research on the motor actuator movement process, the motor actuator and its control system of a 40.5 kV vacuum circuit breaker are developed and verified by closing operation in the selected phase, and the experimental results show the effectiveness of the proposed control strategy.

First-Principles Calculation of Conductivity of Ce-C Codoped SnO2 Contacts

The contact is the core element of the vacuum interrupter of the mechanical DC circuit breaker. The electrical conductivity and welding resistance of the material directly affect its stability and reliability. AgSnO2 contact material has low resistivity, welding resistance, and so on. This material occupies an important position of the circuit breaker contact material. This research is based on the first-principles analysis method of density functional theory. The article calculated the lattice constant, enthalpy change, energy band, electronic density of state, charge density distribution, population, and conductivity of Ce, C single-doped, and Ce-C codoped SnO2 systems. The results show that Ce, C single doping, and Ce-C codoping all increase the cell volume and lattice constant. When the elements are codoped, the enthalpy change is the largest, and the thermal stability is the best. It has the smallest bandgap, the most impurity energy levels, and the least energy required for electronic transitions. The 4f orbital electrons of the Ce atom and the 2p orbital electrons of C are the sources of impurity energy near the Fermi level. When the elements are codoped, more impurity energy levels are generated at the bottom of the conduction band and the top of the valence band. Its bandgap is reduced so conductivity is improved. From the charge density and population analysis, the number of free electrons of Ce atoms and C atoms is redistributed after codoping. It forms a Ce-C covalent bond to further increase the degree of commonality of electrons and enhance the metallicity. The conductivity analysis shows that both single-doped and codoped conductivity have been improved. When the elements are codoped, the conductivity is the largest, and the conductivity is the best.

Remaining Life Prediction of Conventional Low-Voltage Circuit Breaker Contact System Based on Effective Vibration Signal Segment Detection and MCCAE-LSTM

In order to realize on-line mechanical life prediction of conventional low-voltage circuit breaker and improve its operation reliability, a life prediction method based on vibration signal detection is proposed. Firstly, the effective vibration segment that characterizes the mechanical performance of contact system are extracted by combining with the designed signal processing method; then, a multi-channel convolutional auto-encoder long short term memory network (MCCAE-LSTM) life prediction model for individual circuit breaker is constructed, in which the MCCAE is used to obtain the time sequential micro features rich in life degradation information, and the LSTM realizes the quantitative output of the remaining mechanical life; finally, through the actual mechanical life experiment and prediction performance analysis, the effective vibration segment can reflect the mechanical characteristics of the contact system, the measurement method is easy to be carried out on-line, and the average goodness of fit of the prediction model is improved by about 10% compared with the traditional method, which verify the effectiveness of the proposed method.

Effect of extended grading capacitor on the interrupting performance of multi-break circuit breaker during out-of-step faults

The extended grading capacitor (EGC) installed in parallel to multi-break circuit breaker (CB) chamber is a promising technique to suppress secondary arc. The effect of EGC on the interrupting performance of CB during is investigated in this paper. As CBs are subject to various operating burdens in practice, this paper is mainly devoted to the out-of-step fault. Considering the most severe condition, an equivalent circuit model for UHV line is established; the voltages on power source side and line side are derived based on Laplace transform and travelling wave theory, respectively; the expressions of transient recovery voltage (TRV) across CB contact are obtained, and hence the rate of rise of recovery voltage (RRRV). Since the CBs of two power source sides are often cleared asynchronous with a very small-time deviation, the characteristics of TRV waveform for them are separately computed and analysed. Furthermore, a series of sensitivity analysis have been performed. The influences of phase angle, parallel line, shunt reactor as well as reclosure on the interrupting performance are discussed. The results suggest that performance of CB during out-of-step fault is jointly determined by phase angle, parallel line, and especially the reclosure strategy. The EGC can smooth the TRV significantly especially during the first few microseconds of out-of-step fault, the breaking capability would be enhanced.

Pengujian Tahanan Kontak Pemutus Tenaga 70 KV Di Gardu Induk Rengas Dengklok Karawang

The increasing demand for electric power every year demands to provide reliable electric power. One of the important parts to support the reliability of the electric power system is the substation. Substation is a subsystem of the electric powerdistribution system. One of the materials from the substation is a Circuit Breaker (CB) which is a switch that is used to open or close an electrical circuit under load conditions, and is able to connect or disconnect electrical circuits during normal conditions or when a fault current occurs. The CB needs to be maintained to maintain the reliability of CB. This research aims to determine the value of contact resistance in CB. In this research, data were collected from the last 2 periods of maintenancecarried out at the Rengas Dengklok Substation, PT. PLN (Persero) Karawang.Overall with the maintenance and testing of CB contact resistance, the reliability ofthe CB is maintained and can work normally

Research on Three Phase Signal Separation Method and Device for Live Detection of Circuit Breaker Contact Ablation Degree

A three-phase identification method and device for live detection of arc extinguishing performance of circuit breaker are proposed. In this paper, a sensor with three antennas is used to detect the electromagnetic wave radiated by the circuit breaker, and the three-phase identification is realized by controlling the receiving angle of the antenna and comparing the amplitude of the received electromagnetic wave. The method proposed in this paper has the technical advantages of simple implementation and low cost of detection device, and can realize the three-phase identification of live detection of circuit breaker arc extinguishing performance.

Impact of Superconducting Current Limiter on the Gaseous HVDC Circuit Breakers Characteristics

This article combines a mechanical DCCB and commutation circuit charged by resistive superconducting element to study the HVDCGCB arc interruption process during fault occurring and to investigate the transient behavior of the HVDCGCB during switching phenomena using the tools of black box arc model and EMTP-ATP simulation software. at the instant of short-circuit fault occurring, the superconducting resistance becomes a great interrupting resistance to supply the commutation capacitance by the required voltage to drive discharge current through the fault current for obtaining artificial current zero instantly. Developed model has been used for investigating the impact of uncontrolled and controlled parameters such as the factor of power cooling, the arcing time constant and the capacitance and inductance of the commutation element values on the circuit breaker arcing time in the presence of resistive SFCL and in its absence, in order to verify the differences. Results proved that the HVDCGCB with resistive (SFCL) can interrupt the fault current successfully. Arcing time of the fault interruption is reduced to several milliseconds and the interruption capability is extremely improved through commutation capacitance charging voltage and it's discharging current. From the study carried out in the article it is found that the superconducting resistance provides high discharge current leading to improve in the CB interruption process and the rise rate of the re-striking voltage between the circuit breaker contacts decreases with the use of the resistive SFCL, which reduces the likelihood of insulation failure of the circuit breakers. Moreover the impact of resistive SFCL on the HVDCGCB current, re-striking voltage and currents of resonance and absorber elements are investigated. The impact of current limiting resistor on the capacitor's charging current and voltage, is also presented in the article.