Short-circuit Current Interruption Research Articles

The consequence of ignoring load modeling on the circuit breaker selection in densely-meshed sub-transmission systems

In this paper, the selection of circuit breakers for a densely-meshed sub-transmission system with relatively short transmission lines is investigated. The results highlight the significance of modeling the load at the end of lines for accurately calculating the transient recovery voltage (TRV) following the short-circuit current interruption. According to IEEE standards, assuming load modeling at the end of the transmission lines can result in a maximum discrepancy of 20 % in the calculated TRV. Supposing that the load modeling leads to a moderating effect on the calculated TRV, the difference is considered as a safety margin, and load modeling is ignored. Nevertheless, the results presented here illustrate that this assumption strongly depends on characteristics of the studied network and the load type. In a network possessing the characteristics outlined in this paper, even a passive load as small as 15 % of the nominal capacity can significantly moderate the calculated TRV, with impacts reaching up to 38 %. Conversely, modeling an active load may result in a more severe TRV than if it were disregarded. The simulation results indicate that for networks with transmission lines longer than 70 km, neglecting to model passive loads on the transmission lines still yields sufficiently accurate calculations of TRV.

Investigation of Arc Dynamic Behavior Change Induced by Various Parameter Configurations for C4F7N/CO2 Gas Mixture

This study investigates the feasibility of using a mixture of C4F7N/CO2 gases as an eco-friendly arcing medium for high-voltage circuit breakers, comparing its performance to that of conventional SF6 gas. An existing magnetohydrodynamic (MHD)-based arc model is modified to incorporate the non-recombination characteristics of C4F7N. The temperature, pressure, and velocity distributions of the arc throughout the whole arcing process are systematically analyzed. First, the differences in multi-physical fields induced by the C4F7N non-recombination feature are highlighted. The effects of varying the C4F7N concentration from 4% to 10% in the C4F7N/CO2 gas mixture on the arc behavior are also computationally studied. The results indicate significant differences in the arc-extinguishing performance between C4F7N/CO2 and SF6 under identical operating conditions. The potential of using C4F7N/CO2 as a viable alternative to SF6 in circuit breaker applications may need further design efforts to optimize key components such as the driving mechanism and nozzle. Moreover, as the concentration of C4F7N increases, the gas mixture exhibits improved flow field characteristics, suggesting that a higher volume concentration of C4F7N enhances the gas’s short-circuit current interruption capabilities.

Experimental Study of the Pressure Exerted in the Body of a High-Voltage Fuse and Metal Enclosed Switchgear

This article presents the importance of analyzing the breakdown behaviour of high voltage fuses and highlights the pressure values at the fuse ends. The theoretical basis, test scheme structure, design and sizing elements of fuse components, and numerical simulations performed in Matlab/Simulink are presented. The extinguishing environment is not modelled as it is considered to be a vacuum Starting with the oldest overcurrent protection device and continuing with the importance of high voltage fuses for operational safety, the study presents the behaviour of high voltage fuses during short-circuit current interruption. The key element is the value of the pressure on the contacts of fuses, which is often ignored in favour of the pressure of the middle element. When fuses change from solid to liquid state the inner parts are hotter than the outer parts and melt first, and the melting zone extends to the periphery. The study found that the pressure is much higher and is an important value for designers. Experiments showed that the maximum pressure is reached during the arcing period, a significant finding for the design process of the contacts of a high-voltage fuse. The research was then extrapolated to check the pressure in metal enclosed switchgear containing fuse combinations.

Arc Voltage as an Indicator of Nozzle Ablation Degradation in High-voltage CO2 Gas Circuit Breakers

Energy released by electric arc during short-circuit current interruption is mostly absorbed by the surrounding cold gas and partly transferred to the arcing contacts and nozzle. The radiation is the main mode of thermal energy transfer between the electric arc and nozzle surface. Experimental research on the nozzle ablation has been carried out at a model circuit breaker, in which CO2 is filled in the chamber and poly-tetrafluoro-ethylene (PTFE) is used as the nozzle material. It is found that the arc voltage can be as an indicator of nozzle ablation degradation by comparing the voltage at current peak and arc voltage extinction peak. Under 20kA and 35kA peak current interrupting conditions, the voltage at current peak decreases with the number of operations. There are two factors that affect the arc voltage at current peak. One is the size of the arc cross section, and the other is the content of PTFE entering the arc zone, which affects its conductivity.

Experimental Analysis of Degradation in Insulation Performance After Arc-Preconditioning in High-Voltage Circuit Breaker

In the capacitive current switching duty of high-voltage circuit breakers, arc-preconditioning has been standardized to check insulation performance after short-circuit current interruption. Therefore, it is necessary to consider the degradation in insulation performance due to the wear of electrodes and insulators caused by arc-preconditioning. Since insulation performance depends on the electric field and gas density, we evaluated the effects of gas flow and electric field on the stroke position for a product-sized model circuit breaker through fluid and electric field analyses. The impact of arc-preconditioning on insulation performance was analyzed from the breakdown voltage changes before and after arc-preconditioning. The gas density in the high electric field at the tip of the electrode depends on the stroke position, and the electron behavior emitted from the electrode changes with the polarity of the applied voltage. The effects of stroke position and arc-preconditioning on dielectric breakdown performance were systematically evaluated by analyzing a breakdown model that takes into account electron propagation from the electrode tip and changes in breakdown voltage before and after arc-preconditioning. It was found that the degradation in electrodes and insulators due to arc-preconditioning does not uniformly degrade insulation performance, but the degradation effect differs depending on the stroke position, such as when the breakdown voltage does not change.

Design and Analysis of a DC Solid-State Circuit Breaker for Residential Energy Router Application

Energy routers act as an interface between the distribution network and electrical facilities, which meet the requirements of clean energy substitution and achieve the energy sharing and information transmission in the energy network. However, the protection of the dc load side of residential energy routers including interruption and isolation of short-circuit fault currents is vital for discussion. Since the traditional mechanical and hybrid circuit breakers for dc fault protection have the drawback of slow operation, a solid-state circuit breaker (SSCB) is an optimal solution for fast dc fault interruption. In this paper, a dc SSCB is proposed that uses an RCD + MOV snubber circuit, which is considered the best and most complete circuit used in common SSCBs. There are two main contributions in this paper: First, a dc SSCB is designed, which isolates both positive and negative terminals of a circuit and its working principle and operating modes along with the formulas for calculation of crucial time intervals, voltages, and currents along with the design procedure are provided. Second, a soft turn-on auxiliary is designed to prevent a high current surge caused by the capacitance difference between the source and the load. The experimental results demonstrate the proper performance of the topology and the validity of the findings.

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.

Modular DC Circuit Breaker With Master−Slave Concept for Gate Driver Simplification: Topology and Implementation

DC circuit breaker is the key equipment to deal with the interruption of short-circuit current. Compared with the mechanical switch, the solid circuit breaker and the hybrid circuit breaker using the semiconductor device to interrupt the short-circuit current exhibit superiorities in response duration and arc-less characteristics. Massive power devices controlled by corresponding gate drivers which make the semiconductors-based dc circuit breaker bulky and costly are required to withstand the high dc-bus voltage. In this article, the master−slave concept based modular circuit breaker is proposed to simplify the gate driver topology. Only one single gate driver is required to control highly compact modular submodules consisting of power devices, passive components, and diodes. Moreover, the proposed topology can be easily implemented with high flexibility and low cost. Specifically, the gate control function and voltage equalization for series-connected devices can be realized reliably. The master−slave concept and operation principle of the proposed topology are elaborated and the effectiveness has been demonstrated by both simulation and experimental test.

A Relationship Between Vacuum Arc Characteristics and Short-Circuit Current Interrupting Capability at Minimum Arcing Times

The study is to explore a relationship between vacuum arc characteristics and short-circuit current interrupting capability of a fast vacuum circuit breaker (FVCB) at a minimum arcing time. Both a short-circuit current interruption test and an arc mode transition observation test were carried out to explore the relationship. Firstly, an FVCB with ceramic enclosure vacuum interrupter (VI), in which a pair of axial magnetic field (AMF) contacts were arranged, was operated with three different opening speeds to interrupt short-circuit currents. A Weil synthetic circuit provided short-circuit currents of 20, 30, and 40 kA, and a transient recovery voltage (TRV) of 92 kV/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$120~\mu \text{s}$ </tex-math></inline-formula> for the short-circuit current interruption capability experiment. Then, the arc mode observation experiment was carried out under the same conditions as the short-circuit current interruption capability experiment, except for two differences, that is, a glass enclosure VI without a shield was used for observing the arc with a high-speed camera, and the other point was that only the short-circuit current was applied and no TRV was applied. Experimental results showed that the increase in the opening speed resulted in a decrease in the minimum arcing time, the critical arc extinguishing gap, and the critical arc diffusion time, but led to an increase in the maximum arc column diameter. In contrast, the increase in the short-circuit current would increase the minimum arcing time, the critical arc extinguishing gap, the critical arc diffusion time, and the maximum arc diameter. The diffusion of the arc column is essential but not sufficient for the successful interruption. The contact gap plays a significant role. On the one hand, a larger contact gap promotes arc diffuse. The arc diffusion can decrease the contact surface temperature and the local particle density at current zero. On the other hand, a larger gap distance leads to a smaller electric field intensity between fixed and moveable contacts, which reduces the breakdown probability during the postarc dielectric recovery. The critical arc energy density for a successful interruption of the FVCB in short arcing times was obtained to range from 0.54 to 1.01 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times \,\,10^{8}$ </tex-math></inline-formula> J/m3.

SC Curreent Interruption Capability and Protection of SiC Based Solid State Circuit Breaker

This paper presents the short circuit (SC) current interruption capability of a 1.7 kV/72 A silicon carbide (SiC) MOSFET based solid state circuit breaker (SSCB). The interruption process of SSCB is introduced in detail. A test platform is built and the SSCB is tested and discussed at various DC-link voltage, fault inductance and junction temperature. Before the desaturation point (VDS=200 V), SSCB can successfully turn off the SC current. The saturation value of the SC current is positively correlated with di/dt, and the effect of junction temperature (50-150°C) on saturation current is not significant. A SC protection circuit with a response time of 260 ns is proposed and is validated through the test platform.

Design Improvement of Fault Current Limiter Based on High Coupled Split Reactor Considering the Impact of Internal Ground Fault

The fault current limiter (FCL) based on high coupled split reactor (HCSR), namely HCSR-FCL, is a new technology developed in recent years to realize short-circuit current suppression and interruption. This paper investigates the impact of the internal ground fault on the HCSR-FCL, based on the analysis of its basic principle and internal structure, and proposes two improved schemes for the wiring mode and the current-transformer (CT) configuration. Through the theoretical and simulation analysis, the performance of the original scheme and the two improved schemes under various internal ground fault cases are compared. The results show that when the HCSR-FCL of the original configuration scheme is in the current-sharing state and its switch-arm (SA) has an internal ground fault, the current-limiting arm (CA) will lose its shunting function, and the fast switch has to cut off the short current more than twice of the normal fault and bear the excessive voltage, threatening the safety of the FCL and the stability of the system. Both of the two improved schemes can solve this problem, and ensure the reliability and the effectiveness of the FCL, to provide a reference for the development and engineering application of the HCSR-FCL.

Quench and Recovery Characteristics of Solenoid and Pancake SFCLs Under DC Impact Current

With the rapid development of the voltage source converter-based high voltage direct current (VSC-HVdc) power systems, as one of the methods for the suppression and interruption of short circuit current, resistive type dc superconducting fault current limiter (SFCL) is getting more and more attention. As SFCL will quench during the current limiting process, it is necessary to complete the quench and recovery process before the automatic reclosing of VSC-HVdc power systems. In this article, simulation and experimental analysis on SFCL are carried out. The superconducting tape used in the SFCL is the AMSC 8602 YBCO superconducting tape. It is concluded that the simulation results obtained by thermal conduction model using lumped parameter method are basically consistent with experimental results. With the increase of dc impact current and dc impact duration, recovery time of SFCL increases. Recovery time of the solenoid SFCL and the pancake SFCL under different placement modes differs, which is related to the heat dissipation space and the accumulation of bubbles.

Arcing Behaviors in the Large-capacity HV SF6 Gas-blast Interrupters

A comprehension of the dielectric strength recovery processes during the interruption of short-circuit currents in the high-voltage SF6 gas-blast circuit breakers is necessary for their modernisation in order to increase the rated voltage and short circuit breaking current per one break. This paper presents numerical results of the turbulence effects on the interruption ability in the SF6 extinguishing arc chamber.

A Novel Bidirectional Solid-State Circuit Breaker for DC Microgrid

DC microgrid has attracted more and more attention due to its unique characteristics, but the development of a dc microgrid is also facing some challenges, such as interruption and isolation of short-circuit fault currents. Therefore, the dc circuit breaker plays an important role in ensuring the normal work of a dc microgrid. In this paper, a novel bidirectional dc solid-state circuit breaker is proposed to realize the bidirectional flow of energy, which ensures the higher operating efficiency of the dc microgrid. Compared with other solid-state circuit breakers, the proposed novel topology has simpler structure, common ground, and fewer components. First, this paper makes a detailed analysis of the different working stages of the circuit when the fault occurs in combination with simulation results of the circuit topology. Then, the standard of selecting the components through the calculation and analysis of the circuit is given in this paper. Finally, the performance of the novel bidirectional solid-state circuit breaker is verified by experiments.

Online Assessment of Contact Erosion in High Voltage Gas Circuit Breakers Based on Different Physical Quantities

In this paper, an effort has been made to evaluate the online condition of arc contacts as a vital component of interruption chamber in high-voltage puffer-type SF6 circuit breakers. The relationship between eroded mass caused by short-circuit current interruption and different thermal stress indices, such as transferred electrical charge, current squared, and arc energy, is investigated by performing many experiments with different current amplitudes and arcing times. It is demonstrated that none of the known indices can solely determine mass erosion caused by the current interruption. Therefore, the equations including two of the defined parameters are proposed to evaluate mass erosion. The method using arc energy and transferred electrical charge owns the highest accuracy in evaluating mass loss. However, considering the complexity of arc voltage measurements, a second method using current and arcing time can be also utilized. In addition, the development of erosion during the lifetime of arc contacts is studied. It is shown that arc roots tend to form on new uneroded areas of the contacts during current interruption, resulting in different erosion rates between the first few and subsequent interruptions due to change of morphology of the contacts after the first few switching operations.

A Relationship Between Minimum Arcing Interrupting Capability and Opening Velocity of Vacuum Interrupters in Short-Circuit Current Interruption

Controlled switching technology operates circuit breakers at the minimum arcing time for short-circuit current interruption. However, there is no report to reveal a relationship between the short-circuit current interrupting capability with the minimum arcing time and the opening velocities of vacuum interrupters. The objective of this paper is to reveal a relationship between the short-circuit current interrupting capability with the minimum arcing time and the opening velocities of vacuum interrupters. A 40.5-kV fast vacuum circuit breaker prototype was built up which was equipped with a commercial 40.5 kV–31.5 kA vacuum interrupter and it was driven by an electromagnetic repulsion mechanism. It provided an average velocities ranging from 2.5 to 5.5 m/s. A total of 50 times of 40-kA short-circuit current interrupting tests were carried out in a synthetic circuit. Test results showed that the minimum arcing time of successful interruption decreased with the increasing of the average opening velocity. The minimum arcing gap was determined as 1.8 mm and it kept as a constant as the average opening velocity increased. The experimental results also showed a relationship between the arc energy density and the arc extinguishing gap, which acted a linear boundary between the successful and failure short-current interruptions.

Arcing Contact Gap of a 126-kV Horseshoe-Type Bipolar Axial Magnetic Field Vacuum Interrupters

The objective of this paper is to determine arcing contact gap of a 126-kV horseshoe-type bipolar axial magnetic field vacuum interrupter. Drawn arc experiments were carried out in a demountable vacuum. Experimental current ranged from 12- to 40-kA rms. Based on the vacuum arc behavior, minimum arcing contact gap $D_{1}$ and maximum arcing contact gap $D_{2}$ were defined. When average opening speed within 20 mm ( $v_{1}$ ) was 1.9, 2.3, and 2.6 m/s, $D_{1}$ was determined as 15.3, 16.8, and 14.3 mm, respectively. In addition, $D_{1}$ reflected a peak effect with $v_{1}$ . When average opening speed within 40 mm ( $v_{2}$ ) was 2.6, 2.7, and 2.8 m/s, $D_{2}$ was determined as 38.5, 36.7, and 36.1 mm, respectively. Uncontrollable arc mode appeared when current was higher than 32 kA with arc duration of 9 ms. The critical contact gap to avoid uncontrollable arc mode decreased as a liner function of arc current. Based on the experimental results, quantitative design method of three-interval opening velocity for the 126-kV horseshoe-type vacuum circuit breaker was proposed. For short-circuit current interruption test duty T100s, lower limit value of $v_{1}$ and upper limit value of $v_{2}$ were determined as 2.5 and 2.9 m/s with a prospective minimum arcing time of 7 ms.

DC vacuum circuit breaker

In the last years the progressive increase of distributed and non-programmable energy sources arise the interest in the use of DC for medium-voltage distribution systems. The study focuses on the design considerations of the apparatus required to support the management and protection of these applications. The fault-handling techniques in DC distribution system is introduced and the definition of the main requirements for the circuit breakers is supported by computer simulations of short-circuit current interruptions. A medium-voltage DC circuit breaker designed for 12 kV and 2.5 kA nominal current and 15 kA interrupted short-circuit current is presented. The functionalities and the performances are illustrated by means the experimental results obtained from high power tests.

Arcing Time of a DC Circuit Breaker Based on a Superconducting Current-Limiting Technology

A dc circuit breaker (DCCB) based on a superconducting current-limiting technology was proposed for the interruption of short-circuit fault currents in high-voltage dc (HVDC) systems. The proposed DCCB includes a superconducting current-limiting module (SCLM), which is used to limit fault currents, and an interrupter module (IM), which uses a self-excited oscillation method to interrupt the limited current. The objective of this paper is to determine methods that reduce the arcing time of the proposed self-excited oscillation-type DCCB. The self-excited oscillation-type circuit breaker alone is generally unable to interrupt the fault current when it exceeds 8 kA. However, the proposed DCCB can interrupt a fault current of 30 kA when using the SCLM, which can limit a 30-kA fault current to approximately 3.5 kA within 2.5 ms. The arcing time of the IM was also significantly reduced as a result of the greatly reduced interrupting current. The effects of the IM parameters, including the commutation capacitance C 2 , the commutation inductance L 2 , the arc power loss coefficient N, and the arc time constant θ on the arcing time were analyzed. The arcing time can be reduced by increasing C 2 and N and reducing L 2 and θ.

Practical methods for electrical and mechanical measurement of high speed elongated arc parameters

In this paper, we have presented measurement methods used to evaluate short circuit current interruption capability of a fast opening circuit breaker with opening velocities up to 36m/s. Such circuit breakers are the most critical components of future hybrid fault current limiting circuit breakers and therefore thorough understanding of fast elongating arcs is essential. The presented methods include measurement of cinematic parameters (displacement, speed and acceleration) and electrical parameters (arc voltage and current) as well as high speed optical measurement of arc appearance. Generated codes for sampling and wavelet de-noising of signals as well as developed image processing method for processing of digital arc images captured by high speed camera have been explained. Based on processed information gained by the measurements, arc starting time, arc ending time and arc temperature contours have also been calculated. Use of advanced simulation tools based on finite element method (FEM) equipped with moving mesh has been discussed to facilitate measurements and also to improve their accuracy. Practical measurements and simulation results prove each other and show good agreement with digital arc image processing output.