Vacuum Switch Research Articles

The Analysis of the Thermal Processes Occurring in the Contacts of Vacuum Switches During the Conduction of Short-Circuit Currents

This article presents the results of research on the thermal state of vacuum switch contacts during the conduction of short-circuit currents. This state is directly related to the value of the flowing current and the operating conditions of the switch. These conditions are mildest in the case of the conduction of operating currents through closed contacts. The situation worsens significantly when short-circuit currents are conducted, and the greatest destructive effects occur during commutation processes. Exceeding a certain level of contact destruction usually leads to the loss of the switching capacity of the switch. In vacuum switches, tracking the thermal state of the contacts is particularly difficult due to the inaccessibility of transducers or measurement sensors inside the chamber. In such a case, simulation studies verified by experimental results are important. This paper presents the results of such studies, directed at their practical implementation in the design and operation of vacuum switches. Simulation studies were conducted to analyze the thermal processes occurring in the contacts of vacuum switches during the conduction of short-circuit currents. Special attention was paid to the influence of contact parameters on the thermal processes occurring during the conduction of short-circuit currents. In addition to simulations, experimental studies were carried out to verify the simulation results. Ultimately, the research results presented are intended to provide practical knowledge of the design and operation of vacuum switches, particularly with regard to the contact heating processes during the conduction of short-circuit currents.

Research on Conduction Delay Time Characteristics of Double-Gap Surface Flashover Triggered Multistage Vacuum Switch

Due to the insulation saturation effect of a vacuum gap, the series connection is the main method to improve the capability of the triggered vacuum switch (STVS) to withstand voltage. In this paper, a double-gap surface flashover triggered multistage vacuum switch (DMVS) is constructed based on a removable vacuum chamber. The DMVS consists of a surface flashover triggered vacuum gap (STG) and a self-breakdown vacuum gap (SBG) in series. The trend in DMVS conduction delay time under different operating parameters and gap distances is firstly measured through experiments, and then the conduction delay time characteristics of DMVS and single-gap STVS compared. The test results show that increasing the trigger current and operating voltage and decreasing the gap distance of each vacuum gap can optimize the conduction delay time of the DMVS, but the voltage division ratio between the STG and the SBG has no obvious influence on the conduction delay time. The comparison result between the DMVS and the STVS shows that increasing the number of series gaps increases the conduction delay time but, for a certain vacuum gap distance, DMVS exhibits superior conduction delay time characteristics compared to STVS.

Analysis of Electromagnetic Buffer Characteristics of DC Fast Vacuum Switch

In order to solve the contradiction between the rapid isolation of low voltage DC faults and the low bounce of small stroke vacuum switches, taking the fast vacuum switch for 400 V DC power distribution system as the research object, the electromagnetic buffer simulation and experimental research in the opening process are carried out. The influencing factors of the dynamic and reaction mechanism and buffer output characteristics are analyzed, and the electromagnetic buffering effect under typical working conditions is simulated, which proves that electromagnetic buffer is a necessary part of 400 V fast vacuum switch and the motion characteristics of fast switching are optimal when applying 220 V electromagnetic buffer. According to the simulation calculation results, the engineering prototype was made, the experimental research on the electromagnetic buffer under typical working conditions was carried out, and the design criteria of the small stroke electromagnetic buffer were proposed, which solved the problem of fast switching of small stroke and reliable control and low bounce. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Study on the vacuum arc characteristics between novel straight slot transverse magnetic contacts with auxiliary slots on the back

The motion stability of the vacuum arc between TMF contacts significantly affects the breaking capacity of vacuum switches. The vacuum arc movement can be effectively controlled by slots on the TMF contacts to provide the necessary driving force. However, the necessary cross-slot movement of the arc affects its stability. In this paper, a novel straight-slot transverse magnetic field (SSTMF) contact structure with additional auxiliary slots on the back is proposed to improve current distribution and avoid stagnation at the contact center. The simulation analysis was conducted on the force acting on the arc at different positions and the magnetic field distribution between the contacts. Additionally, the arcing experiments were performed in a demountable vacuum chamber for both novel and traditional SSTMF contacts. The SEM analyses were carried out for the contacts after the experiments. Combined with simulation and comparative experimental results, it is verified that the auxiliary slots can improve the control and driving effect on the arc. This can provide ideas and references for future contact design and improve the breaking performance of vacuum circuit breakers.

Investigations on trigger process of triple-gap laser triggered multi-stage vacuum switch

To develop high voltage pulsed power closing switch utilizing the advantages of vacuum gap, a laser triggered multi-stage vacuum switch (LTMVS) is proposed in this paper. Trigger process of triple-gap LTMVS is analyzed based on a detachable vacuum chamber. Closing processes and time-delay characteristics of different gaps in LTMVS are studied later. The results convey that, trigger process of LTMVS can be separated to two periods, the trigger of laser triggered gap, and the cascade breakdown of series connected short gaps under impulse voltage with DC superimposition. Breakdown sequences of cascade gaps are not in stable order, and its delay time mainly depends on the initially breakdown gap. The increase of laser energy and operating voltage benefit to both reducing the delay time of triggered gap and cascade gaps. Under 30 mJ laser energy, delay time of 4 mm laser triggered gap can be controlled within 25.8 ± 1.3ns, and breakdown delay time of 0.8 mm vacuum gap reaches 79 ± 2.5ns. Suggestions for the developments of LTMVS are given based on above researches.

Spin vacuum switching.

Ultrafast control over the magnetic orientation of matter represents a vital element of potential future spin-based electronics ("spintronics"). While physical mechanisms underpinning spin switching are established for picosecond time scales, we here present a physical route to magnetization toggle control, i.e., multiple switching events, at <100 femtoseconds. A minority spin current injected into a ferromagnet is shown to generate rapid depopulation of the minority channel below the ground-state Fermi level, creating a minority "spin vacuum" that then drives rapid charge redistribution from the majority channel and spin switching. We demonstrate that this mechanism reproduces many of the features of recent subpicosecond switching of ferromagnetic Co/Pt multilayers and provide simple practical rules for the design of materials via tailoring the electronic density of states to optimize spin vacuum control over magnetic order.

Comparative Study of Different High Voltage Switches Used in Pulsed High Voltage Application

High-voltage switches play a crucial role in pulsed power applications, where the efficient and reliable control of highvoltage pulses is required. This study aims to compare different types of high-voltage switches commonly used in pulsed power systems including electromechanical switches, vacuum switches, gas-filled switches, triggered spark gaps and solidstate switches. The comparison study focuses on key performance parameters such as voltage handling capability, current carrying capacity, turn-on time, and repetition rates are considered to provide a comprehensive study and analysis of the switch’s suitability for different pulsed power applications. Gas-filled switches such as spark gaps, thyratrons and ignitrons have been used in pulsed power systems due to their high voltage handling capability and low switching losses. However, they suffer from a limited lifetime and require maintenance and periodic replacement. Solid-state switches, i.e. Silicon-Controlled Rectifiers (SCRs), Insulated Gate Bipolar Transistors (IGBTs) and Metal Oxide Semiconductor Field Effect Transistors (MOSFETs) offer advantages in terms of longevity, reliability, and reduced maintenance. However, they have limitations in high-voltage applications and exhibit higher switching losses. The findings of this comparison study will assist researchers, engineers, and system designers in selecting the most appropriate high-voltage switch for pulsed power applications, considering the specific requirements and constraints of the system. This will ultimately contribute to the advancement and optimization of pulsed power technologies across a wide range of scientific, industrial, and strategic applications.

Calculations of static and dynamic processes in the synchronizing shaft of a medium-voltage vacuum switch during the turn-on process

An important direction of theoretical research of modern electrical devices, medium voltage switches and contactors is the study of mechanical processes that occur during their operation. First of all, this is due to sufficiently large forces and accelerations acting on the structural elements and the synchronizing shaft of such devices in the process of switching on. In the article, on the basis of developed mathematical models, calculations of mechanical processes in the synchronizing shaft of a vacuum switch in static and dynamic mode for an absolutely rigid and real shaft are performed and their comparative analysis is carried out. The results of computer modeling are obtained in tabular and graphical forms, which include data on static and dynamic deformations of the shaft, as well as mechanical forces in its supports. It is shown that the mechanical deformation of the shaft causes a decrease in contact drop and contact pressure forces, but with a correctly selected cross-section of the synchronizing shaft, these values slightly affect the operation of the switch itself (the decrease is about 20% and 7%, respectively). It is also shown that as a result of the bending of the shaft, additional axial forces appear in the supports compared to the simplified calculation, which significantly affect the choice of bearings according to the equivalent static load. The calculated dynamic forces, taking into account the masses of contacts and contact rods, exceed similar static forces by 1.3 times, which must also be taken into account when choosing bearings in which the synchronizing shaft is held.

±10 kV DC Vacuum Switch-Fuse Composite Apparatus for Distribution Grid

DC distribution grid is developing fast with the renewable energy industry. For the DC power grid, the DC circuit breakers protect the customers from the short circuit faults but they can't meet all the demands. For those power systems with little short fault probability, this paper provides a potential ±10kV DC composite apparatus, a DC electric fuse parallels with a vacuum switch, an external transverse magnetic field (ETMF) is generated to enlarge the vacuum arc voltage and help the current to transfer. Normally the vacuum switch conducts the rated and overload current, and the short-circuit current can be transferred by the vacuum arc to the fuse which interrupts the current. The ETMF powered by a 2 mF capacitor is more than 200 mT. The electric fuse's design process was supported by finite element simulation to ensure the fuse can interrupt a 5 kA fault current within 5 ms. The experimental results show the DC composite apparatus with a load switch can interrupt 0∼15 kA in 5ms. The interrupting process has been analyzed to understand the characteristics of the breaker, and the vacuum contacts' erosion may cause the interrupting failure. This research enlarged the electric fuse's range of application.

Experimental Study on the Initial Current Characteristics of Laser-Triggered Vacuum Switch During Trigger Process

The trigger characteristics of the laser-triggered vacuum switch (LTVS) are significantly affected by the parameters of the laser-produced initial current. In this paper, a low operating voltage is applied across LTVS, and the trigger experiments are carried out under different laser energy and operating voltage. The initial current is obtained by measuring the voltage drop across a 25 Ω resistor. The influence of laser energy and operating voltage on the trigger characteristics can be characterized by the parameters of the initial current, such as the current peak value, the number of charges released, the rate of rise, and the delay time. The experimental results show that an increase in laser energy can increase the current peak value, the number of charges released, and the rate of rise, and can decrease the delay time. These results show that an increase in laser energy helps the LTVS trigger process. The external electric field is much smaller than the laser electric field. Hence, only the current peak value is affected by the operating voltage, and the impact on the other current parameters is weak.

The motion and distribution characteristics of cathode spot and its influence on plasma parameters

Cathode spots and plasma are the key factors affecting the breaking capacity of vacuum switches. In order to analyze the motion and distribution characteristics of cathode spot and its influence on plasmas, the experiments of cathode spot observation and plasma diagnosis were conducted in this paper. The cathode spot images were captured by ultra high-speed camera. Based on the continuous spectrum theory, the electron density was measured by the colorimetric thermometry. According to the cathode spot images and method of cathode spot recognition, the parameters of cathode spots including number, size and current were obtained. The changes of these parameters with arcing time and current amplitude were analyzed. The dependence of the cathode spots average size on spot current and spot expansion velocity was discussed. The axial and radial distributions of electron density were obtained which is related to the cathode spot distribution on the cathode surface. The significant fluctuation in the radial direction for electron density was observed.

Software for computer simulation of multiphysics processes in electromagnets and actuators of vacuum switching devices taking into account contact interaction of structural elements. Part 2: features of commercial software and open access codes

The first part of the work presented a general overview and classification of software tools for the numerical solution of multiphysics problems of computer modelling of coupled electromagnetic, thermal and mechanical processes in modern complex technical objects, including actuators and electromagnets of vacuum switching devices taking into account contact phenomena when their stress-strain state changes. Criteria for choosing the appropriate software were also proposed and the features of in-house codes for mathematical modelling of technical objects and processes under consideration were analyzed. This paper is the second part of the work and is devoted to a detailed review of commercial codes present on the market and available, as well as open access tools for possible use in performing relevant computational studies, namely, numerical analysis of multiphysics processes in electromagnets and actuators of vacuum switching devices, taking into account contact phenomena by the Finite Element Method. On this basis, taking into account the conclusions regarding in-house codes made in the first part of the work, a selection of specific software for use in the performance of relevant calculation studies is made.

Experimental investigation on “glow flow” phenomenon during current-zero period between transverse magnetic contacts

The inter-electrode state of the transverse magnetic field contact during the current-zero period is determined by the evolution of the arcing process. It has an important effect on whether the vacuum switch can be successfully broken. In this paper, a series of contacts were subjected to arcing and fixed gap distance experiments. The results show that a special inter-electrode phenomenon (glow flow) appears during the current-zero period when the current exceeds the threshold for the transition from diffused to constricted state of the vacuum arc. The mechanism behind the formation of this phenomenon was elucidated through an analysis of multiple sets of experimental results. It is found that the inter-electrode phenomenon arises from the disruption of the equilibrium process between the pressure from the arc column plasma and the anode vapor flux on the near-anode side at the current-zero. The copper vapor falls and is ionized by collisions with heat-emitting electrons. The experimental results and theoretical analysis also show that this phenomenon has a time interval with the reignition phenomenon. When this phenomenon is intense to a certain degree, the reignition will occur with high probability. The observation and theoretical analysis results of this paper are relatively consistent with the research results of other scholars, which can help to improve the vacuum arc characteristics and interrupting mechanism. This can provide a basis for improving the arc extinction performance of the vacuum switch.

Preface

Nowadays, global energy industry is facing much more challenges ever. On the one hand, speeding up the transition to clean, renewable energy is one of the best ways to curb the dangerous carbon pollution that causes environment issue. On the other hand, smart grid and micro grid technology in the power systems are widely expected to improve sustainable energy efficiency. The International Conference on Energy and Electrical Power Systems is a leading academic conference, aiming at building a platform for communication and academic exchange in related fields.This volume contains the papers presented at the 2022 International Conference on Energy and Electrical Power Systems (ICEEPS 2022), held on November 25th-27th, 2022 in Guangzhou, China (virtual event). Everyone interested in this field were welcomed to join the online conference and to give comments and raise questions to the speeches and presentations.The online conference was composed of keynote speeches, oral presentations, and academic investigation, attracting about 150 individuals from all over the world. We have invited four sophisticated professors to perform keynote speeches. Among them, Prof. Kai Wang from Qingdao University, China is one of our keynote speakers and delivered a dramatic speech on the title Research on Life Prediction of Supercapacitor based on Improved Long-Term and Short-Term Memory Neural Network. Next, Prof. Huajun Dong from Dalian Jiaotong University, China performed a speech on Researches on Characteristics of Vacuum Switching Arc and Actuator. And then, Assoc. Prof. Yongzhi Ma from Qingdao University, China made a report on Research on Innovative Design of Split-Type All-Air Air Conditioning in Middle Apartment of Tall Buildings. Last but not the least, Prof. Abdul Hasib Chowdhury from Bangladesh University of Engineering and Technology, China shared with us his study A Talk on Stability and Resiliency of the Bangladesh Power System. All the keynote speakers made brilliant speeches combing their own research domains and experiences, and shared unique experience and insights, creating a great platform for academic communication.ICEEPS 2022 received a great many submissions in the areas of power electronics and advanced control. Each submission was reviewed by at least two expert reviewers and the committee picked out some excellent papers that are included in the proceedings, including but not limited to the following topics: Advanced Power Semiconductors, Control Science and Control Engineering, Electromagnetic Compatibility, Power Electronics and Power Drives, Power System Stability, etc.On behalf of the Conference Organizing Committee, we would like to extend our sincere acknowledgement to all the keynote speakers, peer reviewers, and all the participants. In particular, our heartfelt thanks and appreciation go to the Editors and Managers, Journal of Physics: Conference Series for their help and kind cooperation during the preparation of the proceedings. Hopefully, all participants and other interested readers can benefit significantly from the proceedings and find it rewarding.The Committee of ICEEPS 2022List of Committee member is available in this pdf.

Способ сокращения времени подачи резервного питания в системах электроснабжения с двигательной нагрузкой

Nowadays fast-acting automatic transfer equipment is commonly applied in power supply systems with a motor load since it ensures uninterrupted power supply of critical consumers. However, their application requires the use of high-speed breakers. The implementation of a “high-speed” transfer to a backup power source when using vacuum switches may not be possible due to the long turn-on and turn-off times. Therefore, the purpose of the paper is relevant. The aim of the paper is to study the possibility to reduce the backup power supply time by improving the algorithm to control the vacuum switches of the main and backup power sources in the modes “high-speed” switching by the fast-acting automatic device in case of short circuits in the external power supply network. To achieve this purpose, computer modeling methods are used. They are based on mathematical models of electrical network elements written using systems of differential equations. The authors have defined the regularities of the transient processes in synchronous and induction motors when switching to a backup power source by the fast-acting automatic device in case of short circuits in the external power supply network. It makes possible to set the limit value of the mismatch angle between the residual voltage vectors on the section of the main power source and the voltage of the backup power source, at which the level of the self-starting current does not exceed the values of the starting currents. Also, it makes possible to develop an algorithm to control breakers. The proposed algorithm is based on changing the operation order of the switches of the main and backup power sources. The obtained results show that implementation of the proposed algorithm to control breakers of the main and backup power sources in fast-acting automatic devices in case of short circuits in the external power supply network of the main power source makes it possible to reduce the backup power supply time and decrease the level of self-starting currents that do not exceed the level of starting currents of electric motors without use of high-speed switches.

Study on the trigger characteristics of triple-gap laser-triggered vacuum switch

Multi-gap series connection is an effective way to improve the insulation capacity of laser-triggered vacuum switch. In this paper, a triple-gap laser-triggered vacuum switch (TLTVS) is built using a detachable vacuum chamber. The TLTVS consists of a laser-triggered gap and two self-breakdown gaps. The trigger characteristics of the TLTVS are obtained under different laser energy and operating voltages through experiments. Then a simplified model for the trigger delay time is established to reveal the effect mechanism of laser energy and operating voltage. The experimental results show that the trigger delay time and the jitter time can be reduced by increasing laser energy and operating voltage, but their influence mechanisms are different. The laser energy directly affects the trigger characteristics and the discharge channel impedance of the laser-triggered gap. The latter can link the trigger process of the laser-triggered gap and that of self-breakdown gaps. The laser energy indirectly affects the trigger characteristics of self-breakdown gaps through its effect on the discharge channel impedance of the laser-triggered gap. The operating voltage mainly impacts the field current density flowing through the self-breakdown gap, which in turn affects the trigger characteristics.

Directions of Development of Diagnostic Methods of Vacuum Medium-Voltage Switchgear

The development of power grid infrastructure and increasingly stringent environmental regulations have intensified work, carried out by researchers and electrical equipment manufacturers, to develop innovative gas-insulated, environmentally neutral devices. The emergence of new designs of circuit breakers and disconnectors, in which the resulting electric arc is extinguished in a vacuum environment, requires the development of appropriate techniques for diagnosing the chambers responsible for the dielectric parameters of the device. The following article presents an overview of the directions of development of diagnostic methods for medium-voltage vacuum switching equipment, which can potentially be used to develop a real-time pressure monitoring system that can be applied to vacuum switching equipment used in electrical infrastructure.

Research on the trigger process of surface flashover triggered vacuum switch

The key to promoting the development of triggered vacuum switch is an in-depth research on the physical process of its trigger phase. This paper mainly divides the trigger process into metal electrode melt evaporation, neutral metal vapor layer expansion, electron collision ionization multiplication, and charged particle migration. An approximate analytical formulation of the trigger delay time theory is presented based on a one-dimensional heat conduction model and an electron collision ionization multiplication process. The trigger delay time experimental platform is built with a removable vacuum chamber. The influence factors involved in the mathematical description proposed are studied experimentally. Theoretical analysis and experimental results show that both trigger current rise rate and main electrode operating voltage have an approximate inverse relationship with trigger delay time. The main electrode gap distance is directly proportional to the trigger delay time, but the effect will be weaker as the main electrode gap distance increases. Overall, the consistency of the experimental results and theoretical analysis on influence trends well support the theoretical model.

Software for computer simulation of multiphysics processes in electromagnets and actuators of vacuum switching devices taking into account contact interaction of structural elements. Part 1: general overview; features of in-house codes

For computer modeling of multiphysics processes in complex modern technical objects, for example, in actuators and electromagnets of vacuum switching devices, it is necessary to use modern application software aimed at solving the entire spectrum of the specified problems or one or another "subset" of them. Complexes of applied programs must implement modern mathematical models and corresponding effective numerical algorithms, as well as have convenient interfaces both for the preparation and input of initial information (preprocessor), and for the output and analysis of the obtained results (postprocessor). The presence of the most "user-friendly" preprocessor and postprocessor is extremely important, considering the significant complexity of the processes being modeled, as well as the structures considered by the researcher and/or design engineer. It is of interest to carry out a comparative analysis of specific software products, with the aim of choosing a "tool" for the implementation of a complex of computational studies (computer modeling of multiphysics processes in the structural elements of medium and high voltage vacuum switching devices, taking into account contact phenomena), specified above. The article considers the criteria by which a reasonable choice of software can be made, which will be directly used for mathematical modeling of technical objects and processes under consideration.

Analysis of the fleet and evaluation of the switching resource of 10 kv switches of the branch of pjsc «Rosseti Center»-«Orelenergo»

THE PURPOSE. Analysis of the fleet and evaluation of the switching resource of 10 kV switches of the branch of PJSC «Rosseti Center»-«Orelenergo». METHODS. In the work, based on the database of the branch of PJSC «Rosseti Center»-«Orelenergo», an analysis of the fleet of 10 kV high-voltage switches was carried out, the types of switches used, their shares in the fleet of switches were identified. The park of circuit breakers was investigated according to technical characteristics, including rated currents and currents of maximum breaking capacity in accordance with GOST R 52565-2006 and GOST 687-78, as well as the current standards of the technical organization of PJSC «Rosseti». RESULTS. In the course of the study, it was revealed that the fleet of 10 kV switches installed in switchgear substations with a higher voltage of 35-110 kV of the branch of PJSC «Rosseti Center»-«Orelenergo» is represented by 1833 switching devices, among which: 1197 switches with low-oil arc extinguishing chambers, 636 switches with vacuum, which is, respectively, 65% and 35% of the park. At the same time, 1009 switching devices have a rated current of 630 A, and 366 switching devices – 1000 A, 1526 pieces of equipment have a rated cut-off current of 20 kA. A comparison of a low-oil switch of the VMP type and a vacuum switch BBB with a modern vacuum switch of the BB/TEL series from the point of view of the switching resource in order to justify its use to replace these switches on specific power lines. CONCLUSIONS. Identification of the parameters of the 10 kV circuit breaker fleet makes it possible to develop rational plans for equipment replacement. Analysis of the switching resource of different types of switches allows you to choose equipment with the best characteristics.