Vacuum Circuit Breaker Research Articles

Study on impact of gap difference on plasma distribution of direct current vacuum circuit breaker with double-break

During the fault current breaking process of a mechanical direct current vacuum circuit breaker (DC VCB) with double-break (DB), the mechanism’s dispersion can result in a gap difference between the two breaks. A DB DC VCB breaking experiment platform is constructed in order to investigate the impact of gap difference on plasma distribution during the DB DC VCB breaking process. During the experiment, a high-speed camera is used to capture the vacuum arcing process at the two breaks under varying gap difference conditions. Then, the arc feature parameters and their variations during the zero-zone process are extracted using image processing techniques, and the distribution patterns of plasma and arc energy at the two breaks are analyzed and compared. When there is no gap difference between the two breaks of the experimental DB DC VCB, there are no significant differences in arc energy and the sizes of high-, medium-, and low-temperature plasma zones between the two breaks. When there is a gap difference between two breaks, the break with the smaller gap has larger high and medium-temperature plasma zones, more concentrated arc energy, higher particle concentration, lower arc diffusion velocity and arc energy decay velocity, and a greater amount of residual plasma after the extinguishing of the arc. When the gap difference exceeds a certain threshold, energy spots appear on the contact surfaces, and a high concentration corridor of residual particles remains between the contacts after the current crosses zero, forming a breakdown weak point that eventually leads to arc re-ignition (hence interruption failure) under the action of transient recovery voltage.

Design and Test of Magnetic Shielding for Vacuum Circuit Breaker of CRAFT Quench Protection System

Design and Test of Magnetic Shielding for Vacuum Circuit Breaker of CRAFT Quench Protection System

Coordination of protective relays in the substation

<p class="IEEEAbtract"><span lang="EN-US">To make an electrical system reliable and cost-effective, its protection coordination is crucial. Protection coordination is a study to determine the trip settings of protective devices. This research proposes protection coordination for Mehran University of Engineering and Technology, Jamshoro, Sindh. This study includes the coordination of relays connected at each department to the main relay connected with the main vacuum circuit breakers (VCB) by using the time characteristic curves (TCC) and time delay setting of relays using ETAP software. This method is used for the trip of a particular circuit breaker at a proper time. Hence, if a fault occurs in any department only that department will be disconnected, and the rest of the departments will remain in a working condition. This study helps to maintain the system’s high reliability.</span></p>

33kV cable connector failures due to shunt reactor switching by means of vacuum circuit breaker – A thorough investigation & mitigation analysis

Switching of (small) inductive currents by means of vacuum circuit breakers may lead to multiple re-ignitions. This is the result of the ability of the interrupter's quenching capability, which generates steep overvoltages that can stress the equipment insulation. Should no mitigation measures be applied, the equipment is exposed to a high risk of failure. In this paper, the findings and conclusions of a such a failure investigation and mitigation analysis are presented, referring to multiple cable connector failures in 33kV shunt reactor installations in the Netherlands.

Restrike characteristics of vacuum circuit breaker in its opening process under DC voltage

AbstractThe restrike of vacuum circuit breaker during the breaking process causes overvoltage and intensifies the insulation deterioration of high‐voltage equipment. To solve this problem, the vacuum breaker aging test method and the restrike characteristics are researched. A withstand voltage test platform of 40.5‐kV vacuum circuit breaker was established to obtain the effects of the contact spacing and loop and inrush currents of vacuum circuit breaker on the number of restrike, the wavefront steepness of the breakdown voltage, and the breakdown duration. The number of restrike during the breaking of vacuum circuit breaker decreased and the duration of the repeated‐breakdown arc increased with the increased contact spacing of vacuum circuit breaker. As the loop current of the test system increased, the number of restrike during the breaking of vacuum circuit breaker, the wavefront steepness of the breakdown voltage, and the duration of the restrike arc increased. As the inrush current amplitude increased during the closing of vacuum circuit breaker, the number of restrike and the duration of the repeated‐breakdown arc during the breaking of vacuum circuit breaker increased. The results provide a theoretical basis and data support for the preventive test of 40.5‐kV vacuum circuit breaker and the optimization of the withstand voltage test.

Investigation on Multiple Reignitions Caused by Vacuum Circuit Breaker Switching Off Shunt Reactor Considering Contact Travel in Offshore Wind Farms

The dielectric recovery strength (DRS) of vacuum circuit breaker (VCB) interrupter is closely related to the travel characteristic of contact, which determines the overvoltage caused by switching off shunt reactor (SR) in offshore wind farm (OWF). Firstly, the travel characteristic of contact is analyzed in detail. A field experiment of 35 kV substation is performed and the relationship between contact travel and DRS in different periods is obtained. Then, a novel VCB model considering the travel characteristic is proposed and used to study the arc behavior of the VCB interrupter. The mechanism of multiple reignitions and the sensitivity analysis for switching overvoltage are discussed. Finally, a hybrid method of grey relational grade (GRG) and response surface method (RSM) is employed to optimize the contact travel in order to suppress arc reignition. A group of optimal travel parameters of VCB contact are obtained for minimizing the overvoltage peak.

Wind Turbine Fire Prevention System Using Fuzzy Rules and WEKA Data Mining Cluster Analysis

With the rapid expansion of the supply of renewable energy in accordance with the global energy transition policy, the wind power generation industry is attracting attention. Subsequently, various wind turbine control technologies have been widely developed and applied. However, there is a lack of research on optimal pitch control, which detects wind direction and changes the rotation angle of the blade in real time. In areas where the wind speed is not strong, such as South Korea, it is necessary to maintain the optimal angle in real time so that the rotating surface of the blade can face the wind direction. In this study, optimal pitch control was performed through real-time analysis of wind speed, direction, and temperature, which is the core of wind turbine maintenance, using fuzzy rules using FIS (Fuzzy Interface System) and WEKA data mining cluster analysis techniques. In order to prevent fires caused by the over-current of wind turbines, over-current control methods such as VCB (Vacuum Circuit Breaker) utilization, prototype utilization such as a modular MCB (Main Circuit Breaker) incorporating VI (Vacuum Interrupter), and vacuum degree change analysis methods using a PD (Partial Discharge) signal were proposed. The optimal control technique for wind turbine parts and facilities was put forth after judging and predicting the annual average wind distribution suitable for wind power generation using HRWPRM (Korea’s High-Resolution Wind Power Resource Maps). Finally, the various wind turbine control methods carried out in this study were confirmed through computer simulation, such as remote diagnosis and early warning issuance, prediction of power generation increase and decrease situation, and automatic analysis of wind turbine efficiency.

Experimental study and characteristic analysis of vacuum arc between cup-type axial magnetic contacts under different diameter-to-gap ratios

Since vacuum circuit breakers gradually advanced to higher voltage levels, axial magnetic field (AMF) contacts have drawn a great deal of attention due to their excellent breaking ability. The cup-type AMF contact is a common kind of AMF contact, which has much potential in contact design and application of high voltage grade systems due to the advantages of strong structural strength, uniform magnetic field distribution, lower resistance, etc. This study analyzes the arcing characteristics of a cup-type AMF contact with a large slotted rotation angle at various diameter-to-gap ratios (DGRs). The arcing process is divided into five stages as follows: initial diffusion, contracting, fully constricted, re-diffusion, and extinguished. Arc self-rotation and anode separation phenomena in the re-diffusion stage appear when the DGR is 58/24. The reasons for these occurrences were discussed and explained with regard to the magnetic field vector's spatial distribution. The duration of each stage and the current threshold of a fully constricted arc will both differ with the change of the DGR. The structural parameters of the fully constricted arc were computed through the method of imaging the luminous intensity distribution after the arc was fully constricted. The source of the change in the arc voltage can be seen in the variation of arc structural parameters, which also reflect anode activity intensity to a certain extent. The transient magnetic field simulation method was used to explain why the arc under the same instantaneous current shows variable morphology at the extinguished stage and contracting stage in one arcing process. The research results presented in the article can be used as a reference for developing high-voltage cup-type AMF contacts.

Measurement of zero-zone voltage for vacuum circuit breaker with oscillation zero-crossing circuit

Vacuum Circuit Breaker (VCB) with oscillation zero-crossing circuit is wildly used to interrupt high direct current, especially in the magnet quench protection system. The injection time of reverse current is the critical factor that affect the breaking result. During the current breaking period, the voltage of VCB varies in a wide range, while the arc voltage in zero-zone is very small and changes rapidly. Therefore, the conventional methods cannot meet the voltage measurement requirements. In this paper, a bi-directional zero-zone voltage measurement scheme for VCB was proposed. According to the variation characteristics of transient voltage during the breaking process, the design and simulation verification of the measurement device were completed. Then the high voltage impulse experiment and arcing measurement testing were carried out by the developed prototype of the arc voltage measurement device. The experimental results indicated that the device has fast response and high measurement accuracy, which meets the measurement requirements of VCB zero-zone voltage.

News From Japan

Sulfur hexafluoride (SF <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</inf> ) gas, which is non-toxic, non-flammable, colorless, and odorless, is an important gaseous dielectric medium for high-voltage switchgear, circuit breakers, and other electrical equipment since it is known to have a much higher breakdown strength than air or dry nitrogen and an excellent arc extinguishing ability. However, it has a global warming potential of 25,200 times that of CO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> . Because of this, it is desirable to develop high-voltage and high-capacity apparatuses that do not or rarely use SF <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</inf> gas. From this view-point, Meidensha, Tokyo, has been developing vacuum circuit breakers, as reported in this News from Japan column in the January/February 2015 issue [1]. The vacuum circuit breaker mentioned in [1] used SF <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</inf> for electrical insulation, although a vacuum was used for its interrupters. Recently, Meidensha has developed a 145-kV dry-air-insulated vacuum circuit breaker for the first time [2]. This short article provides an overview of its development.

Research on Motor Drive Technology for an Operating Device of 126 kV Vacuum Circuit Breaker

This study has designed a set of motor operating devices for a 126 kV vacuum circuit breaker (VCB) to improve its reliability and controllability. A finite‐angle permanent magnet brushless motor (FAPMBM) with a multi‐slot stator structure and a dovetail rotor structure has been designed based on the torque and speed requirements of the motor. These requirements were determined by a dynamic analysis of the operating device and its short‐time, finite‐angle working characteristics. The work performance of the prototype motor has been evaluated in an online experiment with a 126 kV VCB, and based on this, a segmented control method has been designed. The motion process of the operating device has been divided into four stages in combination with the output torque demand of the driving motor. At each stage, the output torque of the motor has been changed dynamically to prevent contact collision, shorten the pre‐breakdown time, and make the circuit breaker work more reliably. The results show that the FAPMBM can meet the operating time and speed requirements of the interrupter for the operating device. In addition, the segmented control method improves the work reliability and optimizes the movement of the operating device, which helps the circuit breaker work intelligently. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Electromagnetic-thermal-flow field calculation and optimal design of environment-friendly live tank multi-break vacuum circuit breakers

Electromagnetic-thermal-flow field calculation and optimal design of environment-friendly live tank multi-break vacuum circuit breakers

Study on cathode spot expansion process in vacuum arc with high di/dt

The study on cathode spot under high di/dt condition promotes the application of vacuum circuit breaker in DC transmission and aerospace technology. Cathode spot, as a source of microscopic particles, directly affects the breaking capacity of vacuum circuit breaker. In this paper, vacuum arc with high di/dt was generated in L-C oscillating circuit. The cathode spot behavior was obtained by a high-speed camera. There are two types of cathode spots with different size, different expansion velocity and brightness. The difference in the size of different types of cathode spots leads to the difference in the thermal diffusion velocity of the spots, which is also the main reason for the difference in the expansion velocity of the two types of spots. The influence of spot current density on temperature and electric field is discussed. With the increase of di/dt, the phenomenon of unstable expansion of cathode spots is observed. A new cathode spot is generated in the cold electrode area far away from the previous cathode spot area, resulting in a significant increase in the arc voltage. The expansion characteristics of cathode spot under different current amplitude, frequency and di/dt conditions are obtained.

Simulation and Protection of Reignition Overvoltage in Wind Farm Considering Microscopic Dielectric Recovery Process of Vacuum Circuit Breaker

The high amplitude and steep overvoltage generated by the breaking of the vacuum circuit breaker in the wind farm damages the inter-turn insulation of the transformer. There is a certain difference between the simulation results of the traditional reignition model and the measured overvoltage. It is necessary to improve the simulation model to simulate the overvoltage condition of the transformer more accurately and then select appropriate overvoltage protection measures. In this paper, based on the physical process of dielectric recovery during the opening process of the vacuum circuit breaker, a model of dielectric strength recovery is built to simulate the arc reignition of the vacuum circuit breaker. The model was applied to compare the overvoltage protection effects of RC snubbers, surge arresters, and choke coils. The simulation results show that the overvoltage amplitude and reignition times calculated by the model proposed in this paper are closer to the measured values. Compared with the traditional linear curve reignition model, the accuracy was increased by 24% and 51.2%, respectively. The parameter value of RC snubbers, the connection mode of surge arresters, and the combination mode of choke coil have an influence on overvoltage suppression. Finally, a suitable suppression scheme is proposed by installing a combined arrester on the high-voltage side of the transformer and connecting a choke coil in series, which can limit the phase-to-ground voltage and the phase-to-phase voltage to 2.43 p.u and 3.24 p.u, respectively, and reduce the steepness from 157.2 kV/μs to 22.3 kV/μs.

Optimal Design and Dynamic Analysis of a Spring-Actuated Cam-Linkage Mechanism in a Vacuum Circuit Breaker

This study attempted to establish an optimal design and perform dynamic analysis for a spring-actuated cam-linkage composite mechanism in a rated 12 kV, 25 kA vacuum circuit breaker (VCB). The optimal design of the VCB mechanism involves two steps: the first step involves the optimal design of the stiffness of closing springs and the cam profile, based on three-order polynomial motion curve of the follower; the second step involves the optimal design of a four-bar linkage. To minimize the surplus work in the VCB operating mechanism, the overall difference between the general output force and general resistant force of the VCB operating mechanism during the closing operation was adopted as the objective function to be minimized. Furthermore, the differential evolution algorithm with the golden ratio (DE-gr), an efficient and accuracy metaheuristic algorithm, was employed as the optimization method. The dynamic analysis of the optimal operating mechanism was conducted using a MATLAB-coded program and verified by the multibody dynamic software MSC-ADAMS. The dynamic analysis revealed that the optimal design of the VCB mechanism can considerably decrease the average closing velocity of the movable contact and the Hertz stress between the contact surface of the cam and the roller follower.

Dynamic Model of Medium Voltage Vacuum Circuit Breaker and Induction Motor for Switching Transients Simulation Using Clark Transformation

A derivation of the dynamic model of a medium voltage vacuum circuit breaker and induction motor in space vectors in coordinates αβ0 allow us to model switching transients in various dynamic states of the motor. In the case of the Clark transformation, the corresponding numerical integration technique can be selected including variable time-step integration techniques to avoid numerical instabilities due to the stiffness of the system. Assymetrical operations such as switching cause the power system to become unbalanced and the transformed equations α, β, and 0 are not uncoupled. Therefore, it is necessary to derive a coupling matrix between circuit breaker voltages and currents in the coordinate system αβ0. The subject of our interest is switching overvoltages that arise when turning off small inductive currents by a vacuum circuit breaker. When deriving the model of a vacuum circuit breaker, all its properties encountered during this action are taken into account, i.e., current chop, virtual current chop, dielectric barrier in the circuit breaker and its recovery rate, and the ability of the vacuum circuit breaker to extinguish high frequency currents. Simulation results are compared with the measured results on a medium voltage motor as well as with the simulation results of the mathematical model of the test circuit according to IEC 62271-110 resolved using the nodal method (EMTP algorithm). Models are implemented in the MATLAB/Simulink programming environment.

A Contactless Pirani Approach for Vacuum Monitoring in Vacuum Circuit Breakers

This article presents a method for determining the vacuum state in vacuum circuit breakers (VCBs) based on the Pirani approach. The method relies on exploiting eddy currents (ECs) over a low-cost sheet of iron (target) embedded inside the VCB, which is fixed to the shield of the VCB by a single welding point. This target and its assembly are compatible both with a low-cost manufacturing process and also with the specific fabrication and operating conditions of the VCB. ECs are used both for heating and for monitoring the temperature variation of the target during its cooling. A model based on two exponential kernels has been developed to identify the vacuum state from the cooling kinetics. An experimental setup has been developed to assess the potential performance of the method. The proposed approach is able to discriminate pressures below and above the reliable operating point in VCBs of 10−1 Pa.

Research on Dynamic Voltage Balancing of Series Connected Thyristors in Auxiliary Oscillation Zero-Crossing Circuit

As a mature power semiconductor, the thyristor is widely used in high-power electrical systems. However, its performance and type selection are still worth discussing in some unconventional applications. In this article, the dynamic voltage balancing the performance of series connected thyristors in an auxiliary oscillation zero-crossing circuit designed for a 10 kV/100 kA Quench Protection System (QPS) is discussed. This pulse power circuit contains a bidirectional switch composed of four thyristor stacks, which are used to inject reverse current into the parallel vacuum circuit breaker (VCB) to interrupt the dc circuit. It is proven by both analysis and experiment results that although there is a high di/dt conduction requirement, the ordinary power thyristors are proof that it is more suitable than pulse power thyristors on this occasion for their better transient reverse recovery voltage balancing performance. The phenomenon is explanted by physical principles and measurement results.

The conceptual design of upgraded 100 kA quench protection system for CRAFT superconducting magnet

In the previous scheme of 100 kA Quench Protection System (QPS) in Comprehensive Research Facility for Fusion Technology (CRAFT) project, advanced artificial current zero-crossing technology was used to interrupt the current. Also, the feasibility was verified by both simulation and experiment. However, some significant issues were exposed, including the breaking reliability problems caused by randomness of the post arc and uneven distribution of the recovery voltage in vacuum circuit breaker. In view of the problems, it is of great significance to upgrade the QPS design scheme in CRAFT project. In this paper, a new 100 kA/10 kV QPS topology is proposed, and the working principle of the new topology is introduced firstly. Then the complete commutation process is divided into three stages to carry out a more effective analysis of the theoretical feasibility of the new topology. Furthermore, a series of simulations including the electrical performance of each device in commutation process and temperature prediction simulation of the used semiconductors are carried out. Finally, the optimized design scheme is obtained to meet the technical requirement of CRAFT project. Compared with the previous QPS scheme, the new scheme has much higher action speed and lower cost.

Study on Short-circuit current interruption characteristics of Double-break fast vacuum circuit breaker within the minimum arcing time

It is significant for circuit breakers to expel a short-circuit fault in a short time for the new power grid with high proportional photovoltaic or wind power plants to achieve high transient operating stability. Compared with a traditional circuit breaker, a fast vacuum circuit breaker (FVCB), operated by an electromagnetic repulsion actuator, has an extremely shorter opening time and lower deviation in their opening times. This potentially contributes the FVCBs to interrupting a short-circuit fault current in the first half-wave when introducing a controlled switching technology. Meanwhile, it is beneficial to improve the short-circuit current breaking capacity of the FVCBs by adopting series-connected double-break circuit breaker technologies. This paper aims to explore short-circuit current interruption characteristics of a double-break FVCB within the minimum arcing time. We performed a series of short-circuit current interruption tests in a Weil synthetic test circuit. Two series-connected FVCBs and independent single-break FVCBs were used. Three different kinds of opening velocities were adopted for each of the FVCBs. Results showed that the increase in opening velocity resulted in both a decrease in the minimum arcing time and the critical arc extinguishing contact gap, whether for the single-break or the double-break interruption tests. The ratio of the shared voltage on each of the series-connected FVCBs was about 54 (for the break on the high-voltage side) and 9 (for the break on the low-voltage side). Taking the break with a shorter opening time as a break in the high-voltage side could reduce the minimum arcing time and the critical arc extinguishing contact gap. At the same opening velocity, the sum of the critical arc extinguishing contact gap of the two breaks in double-break interruption tests was significantly higher than twice the critical arc extinguishing contact gap in the single-break interruption tests. This could be caused by the fact that in double-break interruption tests, after the breakdown of one break, even if the break restored insulation, could not share the transient recovery voltage (TRV) before the break broke down. In addition, the sudden drop of TRV without breakdown occurred for the break on the high-voltage side might correlate with the micro-discharge of the vacuum gap. The interaction of the charged particles with the electrode surface would be responsible for the formation and evolution of the micro-discharge in some successful interruption cases.