Arcing Time Research Articles

Research on Dielectric Recovery Characteristic After Large Capacity DC Interruption

The vacuum interrupter-based DC circuit breaker is one of the most important equipments in the DC power system. The dielectric recovery (DR) of vacuum interrupter (VI) is essential for breaking reliability, especially on some occasions with ultra-large fault current such as the outlet of generator. To measure the DR of VI under high arcing current, an experiment circuit is designed and the DR under arcing current from 20 kA to 60 kA is presented in this paper. The influence of arcing current, contact separation, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">di/dt</i> before current zero and arcing time on the DR is investigated. Particularly, it's found that under a specific arcing current, there exists an optimal arcing time for DR, and it shows a negative correlation with the arcing current.

Lexicographic Maximum Flow Allowing Intermediate Storage

In a capacitated network, an optimum solution of the maximum flow problem is to send as much flow as possible from the source node to the sink node as efficiently as possible by satisfying the capacity and conservation constraints. But, because of the limited capacity on the arcs, total amount of flow out going from the source may not reach to the sink. If the excess amount of flow can be stored at the intermediate nodes, total amount of flow outgoing from the source can be increased significantly. Similarly, different destinations have their own importance with respect to some circumstances. Motivated with these scenarios, we introduce the lexicographic maximum flow problems with intermediate storage in static and dynamic networks by assigning the priority order to the nodes. We extend this notion to arc reversals approach, a flow maximization technique, which is widely accepted in evacuation planning as it increases the outbound arc capacities by using the arc capacities on the opposite direction as well. Travel times along the anti-parallel arcs is considered to be unequal and we take into account the travel time of the reversed arcs to be equal to the travel time of the non-reversed arc towards which the arc is reversed. We present polynomial time algorithms for the solution of these problems.

Arc decomposition behavior of C 4 F 7 N/Air gas mixture and biosafety evaluation of its by‐products

At present, reports on the arc interruption and decomposition behaviour of a C4F7N/air gas mixture especially the biosafety of its by-products are limited. Herein, a 57% C4F7N/43% air gas mixture was employed as an arc-quenching medium to conduct 200 breaking tests on a load switch (630 A/24 kV). The arc interruption and decomposition behaviour of the gas mixture were evaluated, and the biosafety of the decomposition products was assessed based on an acute inhalation toxicity test. It was found that the average arcing time of the 200 breakings was about 10.1 ms and that breakings were basically completed at the zero-crossing of the second or third current half-cycle. The gas mixture after breaking decomposed dramatically (the C4F7N content decreased by 75.6%), generating a large number of gaseous by-products (CO, CF4, C2F6, C3F8, CF3CN, C4F8, CO2, C4F10N2, C3F6, C2N2, etc.) as well as solid by-products (carbon particles). The lethal concentration (LC50) of 50% (LC50, 4 h) of C4F7N/air after 200 breakings was 31 ppm (male mice) and 34 ppm (female mice), respectively, and the toxicity was classified as Grade 1. In general, C4F7N has an arc interruption capability, albeit weaker than that of SF6 under the same conditions. After breaking, the C4F7N gas mixture has a relatively high acute inhalation toxicity, and relevant safety protection measures for research or operation personnel are strictly needed.

A novel fault current limiter topology design based on liquid metal current limiter

The liquid metal current limiter (LMCL) is regarded as a viable solution for reducing the fault current in a power grid. But demonstrating the liquid metal arc plasma self-pinching process of the resistive wall, and reducing the erosion of the LMCL are challenging, not only theoretically, but also practically. In this work, a novel LMCL is designed with a resistive wall that can be connected to the current-limiting circuit inside the cavity. Specifically, a novel fault current limiter (FCL) topology is put forward where the novel LMCL is combined with a fast switch and current-limiting reactor. Further, the liquid metal self-pinch effect is modeled mathematically in three dimensions, and the gas-liquid two-phase dynamic diagrams under different short-circuit currents are obtained by simulation. The simulation results indicate that with the increase of current, the time for the liquid metal-free surface to begin depressing is reduced, and the position of the depression also changes. Different kinds of bubbles formed by the depressions gradually extend, squeeze, and break. With the increase of current, the liquid metal takes less time to break, but breaks still occur at the edge of the channel, forming arc plasma. Finally, relevant experiments are conducted for the novel FCL topology. The arcing process and current transfer process are analyzed in particular. Comparisons of the peak arc voltage, arcing time, current limiting efficiency, and electrode erosion are presented. The results demonstrate that the arc voltage of the novel FCL topology is reduced by more than 4.5 times and the arcing time is reduced by more than 12%. The erosions of the liquid metal and electrodes are reduced. Moreover, the current limiting efficiency of the novel FCL topology is improved by 1%‒5%. This work lays a foundation for the topology and optimal design of the LMCL.

Improving Current-Interruption Performance by Using Spiral Electrode for SF6 Disconnecting Switch

To improve current-interruption performance, spiral electrodes were experimentally investigated to magnetically drive an arc. Arcing times for conventional plane electrodes and spiral electrodes were obtained from conducting current-interruption tests and compared. The comparison results indicate that the arcing time in spiral electrodes is about one-third shorter than that in plane electrodes when interruption current is above 900 A. To clarify the principle of improving interruption performance, arc parameters, electrode erosion, and rate of increase in transient recovery voltage were compared for both plane and spiral electrodes. These results revealed that the magnetically driven arc enhances thermal loss of the arc and heat exchange between the arc and ambient gases. Regarding the spiral electrodes, the recovery rate of dielectric strength between the contacts was high. It is thus concluded that current-interruption performance improves by cooling the arc and increasing the dielectric strength by the magnetically driven arc.

Design and short‐circuit current breaking test verification of a 72.5 kV single‐break fast vacuum circuit breaker

Fast clearing of a short-circuit fault is vital to increase the transmission capacity of power grid transmission lines and improve the transient stability of a power system. A fast vacuum circuit breaker (FVCB) is a good candidate to realize quick elimination of a short-circuit fault. The original contribution of this paper is to present the design of a 72.5 kV single-break FVCB and its verification of short-circuit breaking performance. A specially designed 72.5 kV vacuum interrupter, with floating shields and reduced mass of moving components, was developed. An electromagnetic repulsion actuator was used to provide a high initial opening speed, V1, of 5 m/s over half of the full-contact gap and a relatively low average opening speed, V2, of 1.59 m/s in the full contact gap of 30 mm. The high-designed V1 and low-designed V2 were achieved with the aid of a deliberately designed oil buffer. The opening and closing time of the designed 72.5 kV FVCB was 1.2 ± 0.04 ms and 18 ± 0.20 ms respectively. The terminal fault test duty of T100s(b), carried out on the 72.5 kV FVCB, demonstrated both the 40 kArms and 80 kArms short-circuit current breaking performance. The short-circuit current breaking arcing time windows of FVCB, including the minimum arcing time, the maximum arcing time, and the middle arcing time, was verified to fulfill the requirement of the international standard, IEC 62271-100 2017, and the Chinese standard, GB/T 1984–2014, both for the 40 kArms and 80 kArms switching cases, respectively. Further development of the 72.5 kV single-break FVCB would benefit the development of ultra- or extra-high voltage FVCBs by reducing essential numbers of series-connected breaking units.

Interface temperature evolution exposed to arc discharges occurred on the uniform moist pollution layer of composite insulators based on interface fibre Bragg gratings

Arc discharges of moist polluted composite insulators pose a serious threat to the stable operation of transmission line. However, there is no effective detection technology for arc discharges. The evolution mechanism of interface temperature accompanied by arc discharges is not clear. In this paper, a 10 kV composite insulator with quasi-distributed fibre Bragg gratings (FBGs) embedded at the insulator core-housing interface was developed. The temperature calibration experiment of interface FBGs, and the arc discharges experiment of the uniform moist polluted composite insulator were conducted. Applied voltage was controlled to get the continuous arc with an arc time of 46 s and the intermittent arc with an arc time of 8 s. Exposed to the two types of surface arcs, the interface temperature evolution was explored. A new phenomenon of the sharp drop of the interface temperature was observed: the interface temperature first drops sharply and then rises rapidly during the continuous arc. Test results show that quasi-distributed FBGs are valid for detecting the two types of surface arcs by interface temperature rise. This paper provides a technical means to evaluate the state of surface discharges and insulating properties of composite insulators.

Experimental investigation on the velocity of cathode spots in a vacuum arc with high di/dt

With the development of DC transmission and aerospace technology, the demands on the breaking capacity of vacuum circuit breakers (VCBs) under high condition are getting higher and higher. The breaking capacity of VCBs is determined by cathode spots, which provide electrons and metal vapor to maintain the arc. In this paper, the experiments of cathode spot observation were carried out based on the detachable vacuum interrupter and the cup-shaped axial magnetic field contacts. The images of cathode spot distribution were obtained by an ultra high-speed camera. In the initial expansion stage of arcing, it was discovered that the distribution of cathode spots is ring-shaped and symmetrical. The initial expansion velocity of cathode spot ring is approximately proportional to the value of and is independent of frequency. During the whole arcing process, the expansion velocity of cathode spot ring rises first and then drops with arcing time. The effects of the magnetic field and metal vapor density on the expansion process of cathode spot were analyzed. Based on the experimental conditions and results, the values of magnetic field and metal vapor density were calculated which can reasonably explain the variation of expansion velocity of cathode spot.

Experimental Study on the Extinction Characteristics of Secondary Arc Under Different Secondary Arc Currents Near Outdoor Insulator

On the transmission lines, the secondary arc is the arc that remains at the fault point after the short-circuit current is interrupted, which may pose a threat to the stable operation of the power system. In this article, the extinction characteristics of secondary arc near an outdoor insulator under different secondary arc currents are studied experimentally. The secondary arc has different extinction characteristics under different secondary arc currents of 10, 30, and 50 A. The arcing time, length, morphology, diameter, and breakdown voltage of secondary arc are discussed. Experimental results show that, with the increase in the secondary arc current, the arcing time also increases. The development of the secondary arc has stage characteristics. The length of the secondary arc increases steadily in the first stage and fluctuates greatly in the second stage. In addition, during the single discharge in the second stage, the morphology of the secondary arc will change significantly. The breakdown voltage of the upper electrode in the negative polarity is higher than that in the positive polarity, and it is found that this polarity effect is related to the motion of the secondary arc in space. The research results could provide some reference for investigating the physical characteristics and suppression measures of secondary arc.

Capacitive making of double‐break vacuum circuit breaker: Transverse magnetic field contacts are superior to axial magnetic field contacts

Previous studies mainly focused on the behaviours of single-break vacuum circuit breakers (VCBs) in switching capacitor banks. The prestrike characteristics of double-break VCBs subjected to axial magnetic fields (AMFs) and transverse magnetic fields (TMFs) in capacitive making operations, to find a proper structure of double-break VCBs for capacitive switching are experimentally investigated here. Special attention is given to the prestrike gap, inrush current interruption, prestrike voltage, prestrike electric field strength and erosion on contact surfaces of double-break VCBs. The results show that the 50% prestrike gap d50 and the scatter in prestrike gaps are significantly reduced by nearly 50% by the TMF double-break VCB compared with the AMF double-break VCB. The 50% prestrike arcing time ta50 of the TMF double-break VCB can be reduced by 37.0% compared with the AMF double-break VCB. The voltage distribution ratio between two vacuum interrupters (VIs) is more balanced in the TMF double-break VCB (6:4) than in the AMF double-break VCB (7:3) when prestrike occurs. The TMF double-break VCB can reduce the erosion caused by inrush currents on contact surfaces compared with the AMF double-break VCB. In switching capacitor banks, the TMF double-break VCB is superior to the AMF double-break VCB.

Capacitive making of vacuum circuit breakers: Double-break vacuum circuit breaker is superior to single-break vacuum circuit breaker

Previous studies mainly focused on the prestrike phenomena in single-break vacuum circuit breakers (VCBs) under capacitive switching. However, experimental investigations on prestrike characteristics under capacitive making operations of double-break VCBs were not addressed in literatures, which were important for the strategies of capacitive controlled switching. The objective of this paper is to experimentally investigate the prestrike characteristics of single-break and double-break VCBs in switching capacitor banks, to determine the most suitable type of VCBs in capacitive switching. The double-break VCB consists of two commercial 12 kV vacuum interrupters (VIs) with cup-type axial magnetic field (AMF) contacts, which is the same VI in the single-break VCB. The results show that the 50% prestrike gap d50 of each VI in the double-break VCB, which was calculated based on the complementary Weibull distribution, was significantly reduced by 10.5% compared with the single-break VCB. Due to the voltage-sharing effect in the double-break VCB, scatters in prestrike gaps of the double-break VCB were smaller than the single-break VCB. With the application of the double-break VCB, both the inrush current interruption and the prestrike arcing time can be reduced. The double-break VCB can reduce the erosion caused by the inrush current of the low-voltage side VI. In capacitive switching, the double-break VCB is superior to the single-break VCB, especially in capacitive controlled switching.

A Novel Model of Electromechanical Contactors for Predicting Dynamic Characteristics

To ensure the reliability of power supply, a dual power supply structure appears in the power distribution system. Power supply switching is a complex physical process. This paper presents a novel model of electromechanical contactors. This model can simulate the multi-physics process of power switching. This article completes the simulation framework for power switching through contactors for the first time. Among them, the structural topology for contactors is also proposed. On the basis of the novel structure topology, an equivalent magnetic circuit model is established to calculate the relationship between driving force, flux linkage, current, and displacement. Then, a co-simulation model is established between the above equations and Adams to obtain the speed characteristics and flight time of the contactor. Subsequently, through the use of Fluent and its secondary development, a magnetohydrodynamic model is established, and the above-mentioned velocity characteristics are imported into it to analyze the arcing characteristics of the contacts under the conditions of the transverse magnetic field and the insulating grid. The effectiveness of power switching is judged by comparing the flight time of the electromechanical model and the arcing time of the magnetohydrodynamic model. The prototype is manufactured and tested on the basis of simulation. Through experimental waveforms and high-speed photography, the accuracy of the simulation model and the practicability of the contactor are verified.

A Practical Method to Prolong Expiratory Breath Holds for Abdominal Stereotactic Body Radiotherapy

Motion management is crucial to safe and efficacious treatment for abdominal stereotactic body radiotherapy (SBRT). Expiratory breath hold (EBH) treatment is attractive as it does not require sophisticated gating technologies and minimizes abdominal target motion compared to inspiratory breath hold and abdominal compression; however, few patients can perform prolonged EBH to allow efficient treatment. We hypothesized that providing patients supplemental oxygen and controlling respiratory rate (RR) at the upper limit of normal would improve EBH times, increase the percentage of patients eligible for EBH treatment and decrease EBH treatment time.Starting in 2020, we provided patients supplemental oxygen (50% O2 via Venturi mask) with synchronization to a RR of 18 breaths/min with a metronome at the time of CT simulation. Patients were eligible for EBH treatment if they were able to complete two consecutive 20 second EBH. Eligible patients were treated per standard institutional guidelines for abdominal SBRT with EBH. We retrospectively identified all completed EBH treatments with this new supplemented procedure (EBHsupp) from our departmental database. Historical controls treated with EBH prior to this new procedure (EBHRA, where RA = room air) were identified and matched 1:1 based on patient age, sex, RT prescription, number of treatment arcs, and comorbidities via individual matching. Individual patient EBH times, total treatment time, cone beam CT (CBCT) time, and treatment arc time were extracted from the treatment planning software. Statistical comparisons were made with chi-squared test for categorical variables and student's t-test for continuous variables.We identified 8 patients that received 10 abdominal SBRT treatment plans with EBHsupp (two patients had two lesions requiring two separate treatment plans). There was no statistical difference between the EBHsupp and EBHRA groups with respect to patient characteristics. Eight of 11 (73%) screened EBHsupp patients were able to undergo EBH treatment compared to historical department standard of ∼30% with EBHRA. The EBHsupp group had a significant improvement in maximum (50.5 vs 30.9 s, P = 0.002) and median (24.0 vs 17.8 s, P = 0.016) EBH times compared to the EBHRA group and required less breath holds to complete their treatment (9.1 vs 13.9, P = 0.029). Time for CBCT was reduced with EBHsupp (6.5 vs 8.6 min, P = 0.004) and there was a trend towards decreased time for treatment arc completion (3.1 vs 4.0 min, P = 0,10) and overall treatment time (18.6 vs 21.7 min, P = 0.12).Providing supplemental oxygen and controlling respiratory rate at 18 breaths/min significantly improves EBH time. This intervention is simple, inexpensive, safe, and may allow more patients to be treated with EBH while decreasing overall treatment time.C.S. Schneider: None. S. Shen: None. J.B.Fiveash: None. R. Jacob: None.

Analysis of Adverse Influence of Metal Vapor to Arc Movement Between Electrodes with External Magnetic Field Applied by Numerical Simulation

The demand and sustainable development goals for electric vehicles (EVs) have been increasing. A quick charging circuit is an essential technology for EVs. To protect this circuit from faults or accidents, rapid interruption of the arc generated by the switching of direct current contactors (DCCs) is required. However, the DCCs have small sizes and close boundaries against an arc stretch toward the extinguishing chamber. The metal vapor generated by the electrodes causes the arc to remain between the electrodes instead of stretching forward, because the gas electrical conductivity increases when the metal vapor contaminates it. In this study, the arc movements with and without consideration of the metal vapor were simulated numerically to elucidate the influence of metal vapor on arc mobility. It was observed that the metal vapor generated from the electrodes causes the reattachment phenomenon to occur several times on the anode side, which increases the time of arc stretching into the extinguishing chamber. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Experimental and Numerical Analysis on TIG Arc Welding of Stainless Steel Using RSM Approach

This study involves the validating of thermal analysis during TIG Arc welding of 1.4418 steel using finite element analyses (FEA) with experimental approaches. 3D heat transfer simulation of 1.4418 stainless steel TIG arc welding is implemented using ABAQUS software (6.14, ABAQUS Inc., Johnston, RI, USA), based on non-uniform Goldak’s Gaussian heat flux distribution, using additional DFLUX subroutine written in the FORTRAN (Formula Translation). The influences of the arc current and welding speed on the heat flux density, weld bead geometry, and temperature distribution at the transverse direction are analyzed by response surface methodology (RSM). Validating numerical simulation with experimental dimensions of weld bead geometry consists of width and depth of penetration with an average of 10% deviation has been performed. Results reveal that the suggested numerical model would be appropriate for the TIG arc welding process. According to the results, as the welding speed increases, the residence time of arc shortens correspondingly, bead width and depth of penetration decrease subsequently, whilst simultaneously, the current has the reverse effect. Finally, multi-objective optimization of the process is applied by Derringer’s desirability technique to achieve the proper weld. The optimum condition is obtained with 2.7 mm/s scanning speed and 120 A current to achieve full penetration weld with minimum fusion zone (FZ) and heat-affected zone (HAZ) width.

Switching Arc Energy Limitation Approach for LV Circuit Breakers

This paper presents an experimentally verified approach to deriving switching arc energy limitations for low-voltage (LV) circuit breakers (CBs). Air-insulated contactors equipped with additional vacuum-insulated (VI) arcing contacts were tested for AC and DC current interruption efficiency, respectively. In the study, the contact arrangements of reed relay VI contact switches of low current breaking capacity combined with air-insulated contactors were examined. Tests were performed on selected LV CBs inductively loaded for LV power network rated voltages. A comparative analysis of the arc energy resulting from various arc time durations recorded during the switching-off operation was performed. Using a variety of either basic CB air-insulated contact systems or combined contact systems, a practical assessment of the proposed idea for enhancing the arc quenching efficiency was undertaken. As a result of the implementation of the proposed idea, the arc burning duration time was indicated as being hundreds of times shorter. In most cases, a complete arc reduction was achieved. Moreover, the resulting arc energy dissipation during the breaking operation was substantially minimized. Consequently, a significant increase in the total current breaking capacity of the tested CBs was achieved.

Analysis and Tests of the Impact of Permanent Magnets on Current Interruption in a Medium Voltage Rotary Load Break Switch

Abstract The breaking capacity of a medium voltage (MV) rotary SF6 load break switch (LBS) can be improved by incorporating permanent magnets into the stationary contacts. The magnetic field is intended to blow the switching arc root towards a recessed space at the stationary contacts thereby preventing reignition of the arc after current zero. Making and breaking tests of load current 630 A were performed comparing the switching performance of load break switches equipped without a permanent magnet, with a ferrite and with a neodymium magnet. The impact of different polarity arrangements of the magnets in the three phases is also considered and analysed. In order to understand the arc behaviour caused by the effect of permanent magnet, arcing times and arc voltage were measured and evaluated. The results show that the arc voltage depends on the direction of the electromagnetic force, which is determined by the phase current direction but also by the polarity of the magnets. When the force is directed towards the recessed space at the stationary contacts, the arc voltage is notably higher than in the case where the arc is blown in the opposite direction. The higher arc voltage is a reliable indication that the length of the arc is increased, which significantly reduces the risk of both thermal and dielectric breakdowns after the first current zero. The consequences are noticed first in the reduction of the number of missed current zeroes and second in shorter minimum arcing times. An adverse arrangement of the magnet polarity in the three phases increases the number of missed current zeroes.

Study on Arc Evolution Behaviour of Breaking Short Circuit Current for a Fast Vacuum Circuit Breaker

Abstract A fast vacuum circuit breaker (FVCB), driven by an electromagnetic repulsion mechanism, has an extremely short opening time, and in coordination with the controlled switching technology contributes to breaking a short circuit current with the minimum arcing time. The objective of the paper is to determine the arc evolution behaviour of fast vacuum circuit breakers with a minimum arcing time. A 40.5 kV vacuum interrupter (VI) was used, which was equipped with a pair of CuCr50 (Cr 50 wt%) axial magnetic field (AMF) contacts. The diameters of the contact were Φ50mm, Φ58 mm and Φ65 mm respectively. The arc evolution behaviour in the drawn arc experiment was photographed by a high-speed camera through a glass envelope of the VI. The experiment results showed that an initial intense arc tended to evolve into a diffuse arc when the arcing time is larger than a critical arc diffusion time under a certain opening velocity. The critical arc diffusion time for the vacuum arc is defined as arc evolving from the instant of contact separation to an appearance of separated cathode spots. For a Φ50 mm cup-type AMF contact, the critical arc diffusion time decreases from 0.7 ms to 0.46 ms, with the increase of the opening velocity from 2.52 m/s to 4.65 m/s. What’s more, for a Φ58 mm cup-type AMF contact, the critical arc diffusion time decreases from 1.0 ms to 0.58 ms with the increase of the opening velocity from 2.52 m/s to 4.65 m/s. For a Φ65 mm cup-type AMF contact, the critical arc diffusion time decreases from 1.30 ms to 0.64 ms with the increase of the opening velocity from 2.52 m/s to 4.65 m/s. The critical arc diffusion time increases with the increase of the diameter of the contact under the same opening velocity.

How to Reduce the Exposure of Welders to an Acceptable Level: Results of the InterWeld Study.

Workplace measurements in the past have shown that the applicable occupational exposure limits (OELs) are regularly exceeded in practice when high-emission welding processes are applied. The InterWeld pilot study was planned as part of an intervention study to show under which conditions compliance with the OEL is achievable in gas metal arc welding (GMAW) with solid wire. The investigation focussed on local exhaust ventilation, i.e. captor hoods and welding torches with integrated fume extraction. Forty tests with hand-guided GMAW were configured by experts with regard to all technical parameters and carried out by a professional welder. Effects of protective measures and process parameters on the exposure to respirable welding fumes and airborne manganese (Mn), chromium, nickel, and hexavalent chromium were investigated. Personal sampling was carried out in the welder's breathing zone outside the face shield at high flow rates (10 l min-1) in order to achieve sufficient filter loading. Particle masses and welding fume concentrations were determined by weighing the sampling filters. Metal concentrations were analysed by inductive coupled plasma mass spectrometry. In order to evaluate the effects on exposure, the measurements were performed under similar conditions. The data were analysed descriptively and with mixed linear models. For measurements below the limit of detection, the exposure level was estimated using multiple imputation. Two to five times higher exposures to respirable welding fumes and airborne metals were observed during welding of 10 mm sheets than during welding of 2- or 3-mm sheets. Welding fume and Mn exposure were reduced by 70 and 90% when on-torch extraction or a captor hood was applied. Other airborne metals were reduced to a similar extent. Modifications on welding parameters led to a reduction of exposure against respirable particles by 51 up to 54%. Although proper extraction at the point of origin and lower-emitting process variants ensure a drastic reduction in exposure, compliance with current OELs is not guaranteed. In order to ensure adequate health protection, especially at workplaces where thick sheets with long relative arc times are processed, there is a need for technical development.

Study on the Influence of Injected Lightning Current on the Space-Time Evolution of Secondary Arc

The timely extinction of secondary arc is of great significance to the single-phase reclosing of transmission lines. However, very little research has been carried on the space-time evolution of secondary arc under lightning strikes. In this article, considering the electromagnetic force, thermal buoyant force, wind load and air resistance in the motion of secondary arc, a chain arc model was established, which was combined with the double exponential function injected lightning current model. The motion of secondary arc and the change of arc extinction time with or without injected lightning current were observed. The results show that lightning could accelerate the motion of secondary arc and shorten the extinction time of secondary arc. Then, by adjusting the different parameters of injected lightning current function, lightning start time, and lightning duration, the impact of various factors on the motion process of secondary arc and extinction time was obtained. Different wind loads and secondary currents were selected to observe the impact of the same injected lightning current with different secondary current and arc movement environment. The results show that a higher injected lightning current level and a lower secondary current could both make the impact of the injected lightning current more obvious. The lightning duration and lightning start time would not have a significant impact on the extinction of secondary arc. Lightning can reduce the difference between secondary arcs under different winds, and further promote the extinction of secondary arcs. The abovementioned research work can provide some reference for the protection of secondary arc in thunderstorm field.