Typical Motion and Extinction Characteristics of the Secondary Arcs Associated with Half-Wavelength Transmission Lines

Secondary arc discharge is a complicated physical phenomenon and one of the key fundamental issues associated with ultra high voltage （UHV） half-wavelength transmission lines （HWTL）. With the establishment of a physicM simulation platform for the HWTLs, experiments were carried out regarding the motion and extinction characteristics of secondary arcs. The cathode arc root and the anode arc root were found to show an obvious polarity effect while the arc column was moving in a spirM, due to their different motion mechanisms. The extinction behavior was also recorded and experiments were designed with different compensation conditions. Results show that the arcing time can be greatly reduced if there exists an electrical compensation network. The research provides fundamentals for understanding the physics involved, especially the motion and extinction mechanisms of the secondary arcs.     

Dynamic physical characteristics of DC arc on arcing horn for HVDC grounding electrode line

The dynamic physical characteristics of a DC arc on an arcing horn for a high voltage direct current(HVDC) grounding electrode line are significantly different from those of the switching device arc,secondary arc,AC fault arc and pantograph-catenary arc.In this work,an experimental platform for the DC arc on the arcing horn was built,and mechanisms of the arc column short circuit and arc root movement were studied.This work further analyzes the characteristics and mechanisms of the arc motion wh...     

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.     

Arc characteristics during the instability stage on transverse magnetic field contacts

The arcing process greatly affects the breaking ability after current zero. The instability stage is the transition stage from the ignition to the movement stage, which affects the arc movement characteristics. In this paper, the arc characteristics during the instability stage on spiral-type contacts were investigated using a high-speed video camera. A multi-column parallel instability mode and a single-column instability mode were found during the instability stage. The arc appearance and constriction degree changed rapidly. The arc voltage usually increased accompanied by fluctuations. In addition, it was found that the current significantly influenced the arc mode and duration in the instability stage. With increased peak current, the probability of a single-column instability mode increased, and the fluctuation range and average time decreased.     

Research of Arc Chamber Optimization Techniques Based on Flow Field and Arc Joint Simulation

The preliminary design of an arc chamber in the 550 kV SF_6 circuit breaker was proposed in accordance with the technical requirements and design experience.The structural optimization was carried out according to the no-load flow field simulation results and verified by no-load pressure measurement.Based on load simulation results such as temperature field variation at the arc area and the tendency of post arc current under different recovery voltage,the second optimal design was completed and its correctness was certificated by a breaking test.Results demonstrate that the interrupting capacity of an arc chamber can be evaluated by the comparison of the gas medium recovery speed and post arc current growth rate.     

Investigation of Vacuum Arc Voltage Characteristics Under Different Axial Magnetic Field Profiles

Characteristics of the arc voltage under different profiles of axial magnetic field were investigated experimentally in a detachable vacuum chamber with five pairs of specially designed electrodes generating both bell-shaped and saddle-shaped mafnetic field profile. The arc column and cathode spot images were photographed by a high speed digital camera. The dependence of the arc voltage on arcing evolution is analyzed. It is indicated that the axial magnetic field profile could affect the arc behaviors significantly, and the arc voltage is closely related to the arc light intensity.     

Analysis of Fault Arc in High-Speed Switch Applied in Hybrid Circuit Breaker

The behavior of fault arc in a high-speed switch(HSS) has been studied theoretically and experimentally.A simplified HSS setup is designed to support this work.A two-dimensional arc model is developed to analyze the characteristics of fault arc based on magnetic-hydrodynamic(MHD) theory.The advantage of such a model is that the thermal transfer coefficient can be determined by depending on the numerical method alone.The influence of net emission coefficients(NEC) radiation model and P1 model on fault arc is analyzed in detail.Results show that NEC model predicts more radiation energy and less pressure rise without the re-absorption effect considered.As a consequence,P1 model is more suitable to calculate the pressure rise caused by fault arc.Finally,the pressure rise during longer arcing time for different arc currents is predicted.     

基于Saber的5MW中性束注入弧电源仿真设计

强流离子源是HL-2M装置5 MW中性束注入加热系统的核心部件,离子源通过弧电源加速初级电子至高能态,碰撞气体分子,产生等离子体。所以,弧电源对于离子源维持稳定的弧放电非常重要。本文利用Saber软件建立了弧电源的主电路模型,设计并仿真了弧电流的恒流控制、打坑控制以及超级电容的恒流充电控制、恒功率放电控制等。这种方法不仅提高了弧电源电路的分析和设计效率,缩短了系统研制的周期,还可用于实际系统的故障分析和控制参数的整定,降低实验风险。实验结果表明,弧电源的真实输出与仿真输出结果相符。     

Discussion on the Non-Equilibrium Phase of the Gliding Arc Plasma Driven by the Transverse Magnetic Field

a gliding arc driven by the transverse magnetic field was ignited between the electrodes with a complicated shape at atmospheric pressure and a non-equilibrium plasma was gencrated. Under our experimental conditions, a phenomenon was clearly observed where the arc power decreased with the increase in arc voltage. As the arc voltage was higher than 3.375 kV, the are power acquired from the power supply decreased, and the arc plasma began to switch to a non-equilibrium phase. The existence of the non-equilibrium arc plasma was very short, about 10 ms in one gliding arc discharge cycle.     

Performance of the Scattering Matrix Arc Detection System on the JET ITER-like ICRF antenna

Ion Cyclotron Radio Frequency (ICRF) antennas operating under high voltage to couple high power to fusion plasmas are at risk of electrical arcing. The standard Voltage Standing Wave Ratio (VSWR) system does not protect low impedance areas, which are used in antennas to achieve load tolerance to variations in plasma loading during Edge Localised Modes (ELMs). The Scattering Matrix Arc Detection System (SMAD) was designed to create additional protection for these areas, and 4 complete systems were implemented and tested on the ITER-like antenna (ILA) on JET. This paper describes the performance under relevant experimental conditions of load tolerance and/or high voltage and electrical arcing causing generator trip events.     

Pressure and Arc Voltage Measurement in a 252 kV SF6 Puffer Circuit Breaker

The pressure distribution in an arcing chamber is critically important for the SF6 puffer circuit breaker design.In this paper,the pressure variation of four locations in the nozzle was measured by piezoresistive and fiber optical pressure sensors at two current levels of 10 kA and 50 kA.An arc voltage measurement was also taken.The results demonstrate that using either type of sensor with a connecting tube is able to detect the fast pressure variation in circuit breakers,however the possible distortion and delay to the pressure transient caused by the tube need further study.     

The characteristics of primary and secondary arcs on a solar array in low earth orbit

In this paper, the characteristics of the primary arc and secondary arc on a solar array in low earth orbit(LEO) are investigated. The vacuum plasma environment in LEO has been used to study the primary arc and secondary arc of a high-voltage solar array. Silicon solar cells with rigid substrate specimens are used for the experiment. The series-parallel spacing of the silicon solar cells is 1 mm. The string currents of the solar cells are 0.7 A, 1.5 A and 2 A. The primary arc and secondary arc are photographed by high-speed cameras. The differences between the primary arc and secondary arc are observed. The secondary arc can be observed before the primary arc is extinguished. The primary arc is a single arc when the string current is 0.7 A. Multiple arc columns are accompanied by higher arc current. Two arc columns of the primary arc can be observed at 1.5 A string current and 2 A string current. The multiple primary arc columns are related to higher bias voltage. The threshold for sustained arcing is near 145 V/0.7 A, 105 V/1.5 A and 100 V/2 A at 1 mm string gap. Moreover, the transition time of secondary arc formation is analyzed, and found to be about 10–13 μs. The string currents, string voltages and primary arc have no effect on the transition time of the secondary arc formation.     

Design and characteristics of a new type laminar plasma torch for materials processing

Laminar plasma jet(LPJ) generated by laminar plasma torch(LPT) has a favorable temperature and velocity distribution. Thus, it is superior to the turbulent plasma jet in material processing.However, most of the reported LPTs usually operate at a relatively low output power with a relatively low arc voltage and thermal efficiency, which limits its capabilities. In this context, this paper attempts to design a new type of high-power LPT with a relatively low arc current and a high thermal efficiency. In the first section, the design principle of the main components is studied and discussed in detail, and a new high-power LPT is proposed. Then, the experimental characteristics of the proposed high-power LPT are examined. Experimental results reveal the following characteristics of the proposed LPT.(1) The max jet length of the proposed LPT reaches at 540 mm.(2) Its mean arc voltage is higher than 290 V when the LPT works with arc currents lower than 200 A, leading to an output power greater than 50 kW.(3) The mean thermal efficiency is higher than 50%. Lastly, the proposed LPT has been applied to spheroidize the aluminum oxide powers. The experiment results for the production of spherical powders show that the proposed LPT has a good characteristic for material processing.     

Characteristic Analysis of AC Plasma Arc in Water

An experimental system of AC arc discharge in water was designed with pole-pole electrodes and a peak voltage of 1500 V and a test circuit was set up using virtual instrument technology. The mechanism of an AC plasma arc generated in water was analyzed. The voltage- current characteristic of the AC plasma arc was obtained from the waveform. The temperature characteristic was tested with a spectrum diagnosis system, and the effect of different electrode materials on the striking voltage and peak current was analyzed. The results show that when a power supply of 6 KW is applied on electrodes with a gap of 2 mm in water, the striking voltage is from 900 to 1300 V, the arc voltage is from 40 to 100 V, the arc current is from 2 to 7 A, and the zero rest period is from 1 to 2 ms. In addition, the arc voltage and current are different for electrodes in aluminum, copper and stainless steel. The arc voltage is lower and the current is higher for an aluminum electrode than those for copper and stainless steel ones. The highest temperature of the arc is 7643 K.     

The Arc Model in SiO2 Current-limiting Fuse

1. IntroductionIn comparison with other switching appliances,fuse is extraodinarily charasterized by a very higharc voltage and a short breaking time, produced dur-ing breaking the short circuit, therefOre, until now)on composite circuit there have been no equivalent, method of testing the capability for high voltage fuse.The test of breaking capacity for fuses requires a setof power supply which can supply high voltage andhigh current simultaneously. Por alternating current,the power supply i…     

Investigation on the Arc Ignition Characteristics and Energy Absorption of Liquid Metal Current Limiter Based on Self-Pinch Effect

The GaInSn liquid metal current limiter based on the fluid pinch effect has broad application prospects due to its particular properties.However,the limited rated current and ability of power dissipation are the critical problems for its wide application.Firstly,the temperature distribution of the liquid metal current limiter (LMCL) was obtained by experiments with a rated current of 1 kA and the arc ignition phenomenon was observed with 1.5 kA,which indicates that the rated current is mainly limited by the arc rather than the high temperature compared to the traditional switchgears.Furthermore,an improved method is proposed by adding the paralleled pure resistance,impedance or another LMCL element to protect the setup from the fault energy concentration in the setup.The problem of a slower arc voltage increasing rate can be solved by adding a paralleled impedance with suitable parameters.Finally,the current limiting properties based on the improved method were investigated and the alternating oscillating current was found between two paralleled LMCL elements owing to their deviation of arc ignition in reality.     

Coupling model of AC filter branch in SF6 circuit breaker during the break process

In this paper, a coupling model of the AC filter branch circuit with the arc plasma in the circuit breaker was built to investigate the arcing process considering the harmonic current. The comparisons among the current at power frequency (50 Hz), power frequency combining the 11th harmonic and power frequency combining the 24th harmonic show that the high-order harmonic current would lead to higher decreasing rate of current before current-zero period. In addition, the influence of arc on the amplitude of high-order harmonic current is not negligible. Thus, the coupling of arc with AC filter branch circuit is quite necessary in the numerical modeling of the circuit breaker in the AC filter branch at the high voltage direct current converter station.     

EAST强流离子源电源系统的初步测试运行

测试NBI大功率强流离子源的综合测试台正在建设,已研制了离子源等离子体发生器电源系统、等离子体电极高压电源及梯度极分压器、抑制极负高压电源等电源系统,以及高压传输线及缓冲器,在测试台上开展了对EAST中性束注入器第一台兆瓦级强流离子源样机进行整体电源系统测试和离子源起弧放电的初步测试,完成了离子源电源系统初步性能测试及...     

Simulation of Arc Rotation and Its Effects on Pressure of Expansion Volume in an Auto-Expansion SF6 Circuit Breaker

A 3D Magnetohydrodynamics (MHD) arc model in conjunction with an arc move¬ment model is applied to simulate the arc rotation as well as to solve its effect on the pressure in an auto-expansion circuit breaker. The rotation of the arc driven by an external electromagnetic force is simulated in the case with 200 kA of the short circuit current and 16 ms of arc duration. The arc rotating process and the speed of arc rotation have been obtained in the simulation. A comparison of the pressure in the expansion volume with and without an external magnetic field has been carried out based on the calculation results of two cases. The results of the simulation reveal that the arc rotation, which causes more energy exchange between the arc and its surrounding gas, can evidently bring about the pressurization in the expansion volume, which would contribute to more effective arc quenching at current zero and further reducing operation power.     

Characteristics of Single Cathode Cascaded Bias Voltage Arc Plasma

A single cathode with a cascaded bias voltage arc plasma source has been developed with a new quartz cathode chamber,instead of the previous copper chambers,to provide better diagnostic observation and access to the plasma optical emission.The cathode chamber cooling scheme is also modified to be naturally cooled only by light emission without cooling water to improve the optical thin performance in the optical path.A single-parameter physical model has been developed to describe the power dissipated in the cascaded bias voltage arc discharge argon plasmas,which have been investigated by utilizing optical emission spectroscopy(OES) and Langmuir probe.In the experiments,discharge currents from 50 A to 100 A,argon flow rates from 800 sccm to 2000 sccm and magnetic fields of 0.1 T and 0.2 T were chosen.The results show:(a) the relationship between the averaged resistivity and the averaged current density exhibits an empirical scaling law as η∝ j~(-0.63369) and the power dissipated in the arc has a strong relation with the filling factor;(b) through the quartz,the argon ions optical emission lines have been easily observed and are dominating with wavelengths between 340 nm and 520 nm,which are the emissions of Ar~+-434.81 nm and Ar~+-442.60 nm line,and theintensities are increasing with the arc current and decreasing with the inlet argon flow rate;and(c) the electron density and temperature can reach 2.0 × 10~(19) m~(-3) and 0.48 eV,respectively,under the conditions of an arc current of 90 A and a magnetic field of 0.2 T.The half-width of the n_e radial profile is approximatively equal to a few Larmor radii of electrons and can be regarded as the diameter of the plasma jet in the experiments.