空气中直流条件下聚甲基丙烯酸甲酯沿面闪络实验

为研究直流条件下沿面闪络现象及其对绝缘材料的影响,搭建沿面放电系统,对聚甲基丙烯酸甲酯（PMMA）进行了不同电极间距下的沿面放电实验,并对放电前后材料表面的形貌特征、水接触角和表面成分进行分析。结果表明：施加电压过程中,电极附近会出现浅紫色光晕,随着放电距离的增大,闪络电弧的波动性和强度增强。放电后,电极之间形成明显的放电痕迹,越靠近阴极,痕迹越明显。随着放电次数的增加,材料表面呈现淤泥状,粗糙度增大,水接触角降低。材料表面的C1s含量降低,O1s含量升高,大量的C-C键断裂,生成C-O键、O-C=O键等亲水性基团,进一步提高了材料的亲水性。分析表明：材料表面微观形貌和表面元素对闪络电压有一定影响,对材料改性以提高闪络电压具有一定指导意义。     

Portable application of thermal plasma and arc discharge for waste treatment,thermal spraying and surface treatment

Thermal plasma and arc discharge have numerous useful characteristics related to their high temperature and intense radiation. Many applications have been developed. Recently, a portable twin‐torch plasma arc furnace for waste treatment, thermal spraying torches, steam plasma torches, and surface treatment of low‐pressure arc was developed. This paper describes the recent development of a portable application of thermal plasma and arc discharge. The portable device can treat wastes and perform thermal spraying and surface treatments on site. This technology is expected to become more attractive. © 2006 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Controllability of arc jet from arc horns with slits

Ultrahigh-voltage transmission lines must be protected from lightning surges and the large-current fault arcs which follow. Horns which are installed at the jumpers on the strain towers have a role in protecting the insulators from the fault arcs by coordinating insulation strength and holding large-current fault arcs between the horns. Although a flat surface of the electrode tip with a small diameter effectively meets these requirements, it results in the deterioration of corona discharge depressing capabilities in a steady state on power transmission lines. To improve corona discharge depressing capabilities and to reduce deflection of arc jets, finally two types of hemispherical-shaped arc horn electrodes with slits are developed. The arc jet control performance of those horns was disclosed experimentally as follows:

• (1) Two types of arc horn electrodes with our or six slits show remarkable arc jet control performance in the current of larger than 5 kA.
• (2) The addition of a rod-type central electrode at the center of the hemispherical-shaped electrodes results in the considerable extension of arc jet controllability in the wider current zone by containing the arc spot within the tip area of the central electrodes.

Based on the foregoing results, arc horn electrodes with slits have been designed and utilized for practical application.     

低压电器接通电路过程中电接触特性

本文从接触电路过程中电极间电弧放电特性和触头侵蚀特性出发,研究了低压电器接通电路过程中电接触行为的特殊性。     

A new type of ozone generator using Taylor cones on water surfaces

Ozone has been found to be effective in many forms of water treatment. As concerns about the safety of alternate methods of water treatment increase (in particular, chlorination), ozone, which is already extensively used in Europe, offers an effective option. This paper describes a new method of ozone generation particularly suited for use in water purification. Most current industrial ozone production is based on “silent” electrical discharges in a gap between concentric electrodes separated by a glass or ceramic dielectric barrier. The authors present experimental results obtained using a parallel-plate discharge geometry. The lower electrode consists of a grounded “pool” of still water separated by a discharge gap from an upper insulated planar electrode. When the electrode is energized by an AC high voltage, a multitude of “Taylor cones” forms on the water surface. The Taylor cones form and collapse randomly and continuously, depending on the electric field. The tips of the cones provide points for electrical discharge pulses which initiate ozone generation. This method generates ozone in close proximity to the water surface. Laboratory experiments show efficiencies for gaseous ozone production as high as 110 g/kWh     

纳米CuCr50触头材料电弧侵蚀特性

近年来,纳米CuCr触头材料在截流水平、耐压能力等方面的表现优于微晶CuCr触头材料。笔者利用真空触点模拟装置和基于虚拟仪器的电器电寿命测试系统,研究了直流低电压、小电流下的纳米CuCr50触头材料的电弧侵蚀量与分断燃弧时间和触头表面形貌之间的关系,同时采用两种微晶CuCr50触头材料作为对比。利用电光分析天平纳米CuCr50触头材料的侵蚀量,利用电子扫描显微镜测量触头表面形貌。结果表明:纳米CuCr50触头材料的平均分断燃弧时间和侵蚀量均高于两种微晶CuCr50触头材料。纳米CuCr50触头表面Cr颗粒细化及均匀分布,有利于分散电弧。纳米CuCr50阴极触头表面电弧烧蚀比较均匀,而两种微晶CuCr50触头阴极表面电弧局部烧蚀严重,出现明显的凹坑侵蚀。     

Experiments on dependency of metal mixing ratio in Ag-Pd alloy contacts on breaking arc duration,metal erosion and transfer

Breaking arc durations and the differences between the mass of a contact before and after an experiment which is a quantity of metal erosion and transfer (QMET) were measured in Ag-Pd alloy contacts. The experiments were performed in air under particular combinations of voltage, current, and opening speed. The effects produced on arc duration and QMET by different proportions of metals were investigated. In a practical Ag 40 wt% contact, the arc duration was not especially longer and the metal loss was not more than the other ratios. In an Ag 90 wt% contact, the arc duration had a large tendency to become longer under certain conditions and the metal loss was large. The arc duration of Ag 20 wt% had a tendency to become long with the number of operations. The characteristics of arc durations and QMET were different due to two ways of fixing a columnar contact from one side to a holder and from two sides. The curves of QMET were zero-crossed and the mixing ratio for QMET became zero for one of the two electrodes. This paper possibly suggests some way to design electrodes for heat produced in the Ag-Pd alloy contact, and the possibility of zero QMET.     

不同接触电阻的气体扩散电极性能研究

在催化剂与泡沫镍基板之间,采取涂抹式和表面接触式两种方式制作了具有不同接触电阻的气体扩散电极,通过观察微观形貌从理论上说明两种电极的接触方式引起的放电效果区别;结合在锌空气动力电池中的放电实验,获得在同等实验条件下,电极催化剂与基板采取表面接触式比涂抹式制作方式产生的电池表观内阻值高0.05Ω,当放电电流密度值为106mA/cm2,放电电压值低0.09V。说明了气体扩散电极由于催化剂与基板接触方式不同引起的接触电阻变化对电池放电状态的影响及其影响程度。     

Time-domain temperature variations of a composite insulator surface exposed to arc discharges

In this paper, a system of equations is presented, which describes time-dependant temperature variations for a dielectric surface exposed to an arc discharge. The formulas are derived for a circular (as well as any-shape) region interacting with the arc discharge. The final set of equations makes it possible to convert temperature values, measured at some depth beneath the sample surface which is exposed to the arc heating, to the corresponding surface temperature values. The theoretical results are verified by measurements according to the IEC 61621 test method, and numerical calculations are done for an epoxy composition that is used in composite insulator manufacturing.     

强电接点电侵蚀解析模型和应力分布模型

对油断路器电接点电侵蚀凹坑的形成以及电蚀坑表面层状态进行了分析。建立了电接点电侵蚀沿电极深度方向上的温度场分布解析模型和解析表达式。给出了电接点放电结束后冷却温度场变化的解析方法。并对凹坑表面层残余应力的形成机理进行了较为详细的分析。建立了电侵蚀凹坑表面层残余应力分布的物理模型,给出了电侵蚀凹坑表面层残余拉应力区长度的计算方法。     

Latest technical trend of arc plasma,electrical contacts,and their applications

Arc plasma generated by arc discharges is used in various fields because of its extraordinary characteristics such as very high temperature and high energy density. On the other hand, the principle of current interruption by extinguishing the arc discharge between electrical contacts is practical and useful in many types of circuit breakers. Arc discharge and electrical contacts have been well investigated, and numerous procedures have been developed. In this review paper, we introduce the recent technical trends in arc plasma treating wastes, synthesizing new materials, and the latest circuit breakers equipped with arc plasma and electrical contact techniques. Copyright © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Production of ozone by surface and glow discharge at cryogenictemperatures

The generation of ozone at cryogenic temperatures is investigated with a special interest in increasing the yield of ozone by using low temperatures of liquid natural gas. Two modes of plasma chemical processes are studied, both based on electric discharges: one is the high-frequency surface discharge mode under ordinary gas pressure and at a temperature above the liquid temperature of ozone at this pressure (-111°C); the other is the glow discharge mode under a low gas pressure (0.5-2.0 torr) and low gas temperature (-190°C). The surface discharge mode uses a novel ozonizer developed by the authors made of 92% high-purity alumina and tungsten electrodes sintered together. This ozonizer has an extremely high resistance to large temperature gradients and thermal shock, which is a prerequisite for cryogenic operation. The glow discharge mode uses a Pyrex glow tube with a separate liquid-ozone collector. A dramatic improvement in the energy yield of ozone generation is achieved in both modes of cryogenic operation. The results of preliminary test for cryogenic ozone generation are very encouraging     

二维交流滑动弧放电物理参数分析

笔者对刀片式交流滑动弧放电过程进行了系统的分析,考察了进气流量、电极间距等因素对放电电压、电流、放电功率、对流换热等物理参数的影响.实验结果表明:当流量较低,如0.9 L/min时,放电电压随着弧长增加呈现二次曲线增长;当流量提高,超过10 L/min时,放电电压在电弧较短区域变得紊乱.放电功率随着气流量的增加.先线性...     

大气压反常辉光放电特性

为研究大气压反常辉光放电的特性,用50 Hz交流电驱动1:500的高压变压器产生稳定的大气反常辉光放电,并利用示波器对其作了测量。维持稳态放电的典型参数为电压400~850 V,电流60~110 mA,其伏安特性曲线表明放电处于反常辉光区。当放电的原始驱动电动势取为余弦波形时,放电端电压呈方波形,放电电流呈正弦波形。对放电过程的电路分析表明,高压变压器次级线圈固有的高感抗产生的负反馈避免了放电进入弧光区,由于电路的感抗特性,余弦电动势驱动了正弦形放电电流。而等离子体电阻对放电电流的非线性响应使得放电端电压呈近似方波形。估算得到放电通道中电子平均温度和电子密度分别为2.73 eV和3.45μm-3。用热电偶测得等离子气体温度为700~900 K。该种等离子体相对于其它冷等离子体具有较高的等离子体气体温度和能量密度,更适宜于一些化学气相反应。     

Optical studies of surface discharge under dc voltage in vacuum

Utilizing a high-sensitivity photomultiplier tube (PMT) and an intensified charge coupled device (ICCD) camera, the light emission from the surface of polytetrafluoroethylene (PTFE) and alumina ceramic samples was investigated in vacuum under a stepped dc voltage in order to study the initiation and development of surface discharge. Different from the classical electrode contact by butting electrodes on a sample directly, to achieve a fine contact between electrodes and the surface of a sample, the metalized electrodes were employed by sputtering two additional gold contacts on each sample in advance. The two types of materials showed quite different optical characteristics. It was suggested that there were several processes possibly related to the initiation mechanism of the surface discharge. Besides the field electron emission from the cathode triple junction (CTJ) for the classical electrode contact, there were charge injection and transport in the surface states of dielectrics, and charge trapping and detrapping phenomena. Electroluminescence (EL) emission was emitted due to the radiative recombination of electrons and holes injected. These processes were strongly dependent on the electrode contact manner and the surface states of insulating materials.     

D. C. Surface Discharge Characteristics in Mach 2 Rarefied Airflow

The paper describes a study of an electrical discharge in a supersonic rarefied air flow. The discharge is created by applying negative DC potential difference between two electrodes flush mounted on the surface of a quartz flat plate placed in Mach 2 continuous airflow. The electrodes are arranged in spanwise direction. Two discharges are studied. In the first one, the negative potential is applied to the electrode placed close to the leading edge. In the second one the potential is applied to the electrode placed close to the trailing edge. Current-voltage characteristics, spectroscopic analyses, electrostatic probe and surface thermal measurement will be presented. Luminous emission pattern and potential measurements show that the plasma is similar to a low pressure tube discharge modified by a nonuniform density field of the flow. A comparison between current voltage characteristics of the upstream and downstream discharge shows the effect of the density field on the discharge. Thermal and spectroscopic measurements also show that the plasma induces a surface and volume heatings.     

开关触头的熔池尺寸

开关触头在高弧高温的作用下，产生熔池，继而发生喷溅，是电弧侵蚀的重要方式之一。通过计算触头温度场，分析了影响触头熔池尺寸的因素。结果表明，热流功率Ｐ和分断时刻ｔ０对熔池尺寸有显著影响。     

杯状纵磁真空灭弧室三维涡流场仿真

对杯状纵磁真空灭弧室触头建立了与实际触头结构完全一致的有限元分析模型,模型中把电弧弧柱处理成圆柱形金属导体.对模型用有限元法进行了三维涡流场仿真.仿真结果表明,考虑电弧以及杯和电弧的涡流效应后,在电流峰值时,触头片中电流密度最大值变大;触头片上槽一侧的纵向磁场比另一侧强;磁感应强度B矢量在触头表面上的分布呈"旋涡"形状,其纵向分量在触头中心较大,越靠近触头边缘越小,而横向分量则增大;电流过零时,与未考虑电弧以及杯和电弧的涡流效应时的计算结果相比,触头间隙中心平面上及触头表面上的纵向磁场分布变为"帐篷"形状,纵向磁感应强度最大值也变大.在触头开距中心处纵向磁场较强且纵向磁场滞后时间也相对较长.     

Arc propagation over electrolytic surfaces under power frequencyvoltage

Flashover of wet polluted insulation is caused by the propagation of arcs along the electrolytic surface. Several factors affect this flashover process under actual operating conditions. These include the variation in pollution resistance due to arc root movement and thermal effects. The difference between the discharge gradient and the effective pollution gradient is an important factor in determining the growth of the discharge. Moreover, the distribution of instantaneous power along the wet surface also affect the arc propagation significantly. This paper describes the different physical criteria controlling are propagation, over electrolytic surfaces under ac voltage application. Contrary to the existing concept of a critical point, from where the discharge takes the final leap to complete flashover, the results obtained show that there are critical zones, referred to as the growth period lying between 40 to 63% of the total pollution length, which depends on the degree of surface pollution and the nature of pollutants     

Generation of CNTs on STM Probes Using the Simple Arc Discharge Method

We succeeded in producing carbon nanotubes (CNTs) on scanning tunneling microscope (STM) probes using the simple arc discharge method. We used STM probes with a diameter of 200 µm (500 nm in diameter at the tip), and placed them in a position 5 mm from a set of carbon electrodes between which a direct current discharge of 30 V/20 A was applied. The results of scanning electron microscopy observation confirmed that the fine particles generated included high-purity CNTs on the STM probe surface. Specifically, CNTs were generated directly on the surface of the STM probe. This study indicates that the technique is suitable for nano-analysis application in the field of nanotechnology. © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.