三相组合式过电压保护器高压引线的正确安装

在配电系统中选用三相组合式过电压保护器（简称TBP）很普遍。笔者在现场发现，由于不注意正确的安装方法，使TBP保护性能变差。该产品出厂时有一段较长的高压引线（软导线），是为了适应用户不同安装距离的需要。但有些安装工人习惯把多余的高压引线圈扎起来，这样做的结果，实质上是增加了冲击电流下的电抗，使过电压电磁波不能迅速导入大地。因为避雷器动作时，放电电流达数百安，而放电时间仅数百微秒，     

植物遗传工程的载体

高等植物的遗传工程,旨在用分子生物学和细胞生物学的方法,把外源遗传物质——目的基因或含有目的基因的DNA片段,通过载体或其它技术导入受体细胞并使之发生遗传转化,再利用植物细胞的全能性来获得转化了的植株。本文主要介绍近年来,寻求植物遗传工程载体系统的研究概况。     

中性束注入器用串联高压缓冲器优化设计

为了优化中性束注入器(NBI)用高压缓冲器的布局,分析了缓冲器结构设计参数和缓冲器性能的相互关系,并通过等效电路仿真模型修正了缓冲器放电峰值电流经验公式,得到了不同激励信号下串联高压缓冲器在高频脉冲放电情况下的特性,最后,在高压缓冲器理论分析和仿真分析的基础上,对设计的非晶缓冲器和Deltmax缓冲器串联高压测试件进行了短路放电测试,得到了短路放电瞬间串联缓冲器的分压和回路的放电电流。放电实验结果表明,黑色非晶缓冲器感应电压频率响应比较快,Deltmax缓冲器可以消耗更多的故障电流能量,非晶缓冲器和Deltmax缓冲器这2种不同直流缓冲器的串联能够有效地抑制高压直流故障短路电流并吸收故障电能。     

BNS-Na对碱锰电池放电性能的影响

研究了在锌膏中加入BNS-Na对碱性锌锰电池放电性能的影响.锌膏中加入BNS-Na后,新制和储存电池在小电流放电下性能没有提高,中等电流放电下放电高压段有所提高,当BNS-Na含量为10%时,大电流放电性能提高约10%.     

电子枪高压放电的危害及其对策

介绍了电子束焊机运行过程中电子枪发生高压放电现象对焊机各部件产生的危害,并提出了抑制高压放电冲击电流的措施。     

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。     

抑制电子束轰击炉中高压放电的方法

介绍了电子束轰击炉高压直流电源的工作原理,分析了大功率电子枪高压放电现象,并提出了抑制放电电流,降低其危害性的方法。     

排针-辊式电晕放电特性

为提高高压静电分选效率,寻求产生最佳电场的新型排针电极结构,采用自制新型排针–辊式高压放电装置,探究了放电针直径对电晕放电性能的影响;设计了一种新的测量装置,实现了对单根及多根放电针上放电电流的测量,为了在相同电压下得到更好的放电效果,对35根放电针中的偶数序号放电针缩进5次、每次5 mm,进行比较研究;在MATLAB平台上,利用电磁场理论,对不同缩进条件下排针型电极的空间电场分布仿真模拟。结果表明:其他条件一定,放电针的直径越小,排针总的放电电流(排针电流)及每根针放电电流(针电流)越大;随着偶数序号放电针缩进长度的增加,排针电流呈先增大后减小的趋势,在缩进长度为15 mm时,排针电流达到最大值,空间电场强度最强,此时为最佳电场的新型长短针的排针结构。电场模拟结果与实验相一致,印证了排针中缩进的偶数序号放电针对突出的奇数序号放电针的放电有加强作用。     

放电线圈引起电容器组不平衡电流保护动作分析

为保证高压并联电容器组能够安全可靠运行,解决由于放电线圈自身缺陷、使用不当、并发性故障等产生不平衡电流的问题,着重研究放电线圈对单星形桥式并联电容器组不平衡电流保护的影响。具体分析了不平衡电流保护原理,阐述了放电线圈的作用,并仿真验证放电线圈故障引起不平衡电流保护动作的原理。通过实际案例具体阐述了保护动作后故障分析的方法,提出了故障定位和常规试验的建议。     

冲击电压下典型局部放电信号的光电检测系统

脉冲高压下测量设备的局部放电是一种校验高压电气设备在冲击电压作用下绝缘性能与设备老化的有效方法。检测局部放电对于及时发现设备故障隐患、确保安全运行具有重要的实际意义。搭建了油纸绝缘气隙模型,利用光电检测方法,实现在高压端测量冲击电压下的局部放电,具有较高的响应特性。在试样高压端串入采样电阻,通过光学元件将采样电阻上的电流信号转换为光信号进行传输,降低了空间电磁干扰的影响,最后通过光电转换装置实现电流信号的采集。实验结果表明随着电压的升高,局部放电强度愈发剧烈,验证了光电检测方法在冲击电压下检测局部放电的可行性。     

Calculation of magnetic near field generated by the contact discharge of an ESD gun

An ESD (electrostatic discharge) testing is specified in the IEC 61000‐4‐2, in which the detailed waveform of the discharge current injected by an ESD gun is prescribed. However, due to lack of understanding of the discharge process, it is difficult to confirm whether or not the IEC current waveform can be injected onto actual equipment. We thus previously proposed an equivalent circuit model for the ESD gun based on its geometrical structure, and showed decisive factors for the discharge current. In this study, in order to confirm the feasibility of the above equivalent circuit model, we measured with a 6‐GHz wide‐band digital oscilloscope the discharge current through an SMA connector and the resultant magnetic near field for the contact discharge of an ESD gun. As a result, we found that both measured waveforms approximately agree with those calculated from our equivalent circuit model. We then measured with respect to charge voltages the magnetic near fields for the contact discharge of the ESD gun to the ground, which revealed that the measured waveform around the first peak is in fair agreement with the calculated one. Furthermore, we found that the magnetic field peak increases with increasing charge voltage, whose dependence can be predicted from our equivalent model. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 153(1): 17–24, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20194     

Equivalent circuit modeling of discharge current injected in contact with an ESD‐gun

The transient electromagnetic (EM) fields caused by an electrostatic discharge (ESD) have broadband frequency spectra, which cause serious failure to high‐tech information equipment. From this perspective, ESD testing for the EM immunity of the equipment is specified by IEC 61000‐4‐2, in which the detailed waveform of the discharge current injected onto the IEC recommended Pellegrini target in contact with an ESD‐gun is prescribed for calibration. However, the factors for determining the current waveform remain unclear, and thus the IEC prescribed current waveform is unlikely to be injected into actual equipment. In this study, based on the structure of an ESD‐gun, an equivalent circuit modeling is proposed for analyzing the discharge current injected onto a 50‐Ω SMA connector instead of the IEC target that has frequency‐dependent transmission characteristics. Its validity is confirmed by comparing the calculated current waveform with the measured result. The proposed circuit modeling is also validated from measurement of the discharge current injected onto a transmission line by the ESD‐gun. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 149(1): 8–14, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10367     

Characteristic measurement of discharge current injected by the air discharge of an ESD gun onto a ground

An immunity testing method for electrostatic discharge (ESD) is being specified in IEC 61000‐4‐2, in which the contact discharge of an ESD gun is being normally specified. Air discharge testing is known to be a severe immunity test compared to contact discharge testing, while the discharge current injected is not well reproduced. Grasping the behavior of the current injected by the air discharge would be helpful in establishing the worst‐case ESD immunity testing. We previously measured the discharge currents for air discharge testing onto the IEC‐recommended current transducer with a commercially available ESD gun, and showed that there exists a specific relationship of Ip·tr^ξ/V_c=constant (ξ=0.75), between rise time tr and current peak Ip. The current transducer, however, has a frequency‐dependent transfer impedance which should affect the measured current waveform. In this study, we investigated whether the above‐mentioned specific relationship can be obtained for air discharge of an ESD gun onto a ground that assumes a metal enclosure of electronic equipment under test. A method was presented for estimating the discharge current from simultaneously measured magnetic fields with two magnetic field probes regardless of the distance between the gun discharge‐point and the probe position. This method was validated for contact discharge of an ESD gun to an SMA connector. With this method, we estimated the discharge currents injected onto a ground for air discharge testing of an ESD gun with intentionally fast and slow approaches. As a result, we could confirm a specific relationship between rise time tr and current peak Ip of Ip·tr^ξ/V_c=constant with ξ=0.57 independent of charge voltages and gun approaches. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 158(4): 51– 59, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20454     

Variations in discharge current waveforms and their power spectra injected from contact discharges of ESD‐gun with different arrangements

The International Electrotechnical Commission (IEC) has prescribed an immunity test (IEC61000‐4‐2) of electronic equipment against electrostatic discharges (ESDs), in which a discharge current to be injected onto equipment under test is specified. As for the waveform, however, not the whole waveform but only the rise time, the first peak, and the current amplitudes at 30 and 60 ns are given in the time domain together with their uncertainties, which are required to check on the condition that an ESD generator (ESD‐gun) shall be arranged vertically to an IEC‐recommended calibration target and its earth return wire is kept away as far as possible from a vertical ground plane (IEC standard arrangement). In this study, to clarify how arrangements of an ESD‐gun and its earth return wire affect discharge currents, we measured discharge current waveforms for contact discharges of an ESD‐gun onto an IEC calibration target with respect to various inclinations of the ESD‐gun and arrangements of its earth return wire, and also calculated their current power spectra normalized to that of the discharge current for the IEC standard arrangement. As a result, we found that inclinations of the ESD gun affect the first peak current, which increases current power spectra by 14 dB at frequencies over 300 MHz, and that arrangements of the return wire influence the current waveforms between the first and second peaks, which provides variations in power spectra by ±12 dB in the frequency range from 10 MHz to 200 MHz. This finding suggests that arrangements of an ESD‐gun and its earth return wire are likely to cause different immunity test results. It was also found that in comparison with measured discharge currents for the standard arrangement, the calculated waveform of a discharge current from a formula, which has been included in the recent standard, has a more gentle falling waveform, and produces power spectra of +15 dB in the frequency range from 10 MHz to 200 MHz and –12 dB at frequencies over 300 MHz. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 180(1): 9–14, 2012; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21270     

高压大功率太阳电池阵防静电措施评价试验

高压大功率太阳电池阵在轨运行期间由于静电放电问题引发故障,会造成太阳电池阵功率的大幅度损失。因此进行了本次评价试验。试验采用在真空环境下通过电子枪模拟空间带电环境,诱使太阳电池阵产生一次放电乃至二次放电。在试验过程中未采取保护措施的参比样品发生二次放电被击穿,而采取保护措施的飞行样品未发生二次放电。通过试验,验证了该高压大功率卫星太阳电池阵的设计是可靠的,所采取的保护措施是有效的。试验取得了圆满的结果。     

电力调峰方式及其存在的问题

针对目前国内调峰任务的日益突出及世界电力发展情况,分析了国内外的主要调峰方式及主要调峰方式存在的问题,并论述了需求侧管理在调峰中的作用。指出随着电网容量的不断增大,生产具有调峰能力的大容量火电机组,并大力提高机组运行的自动化水平,已成为今后发展我国电力工业的当务之急。蓄能调峰是我国乃至世界电力工业调峰的必然趋势,氢能、太阳能和闪电也是可以作为调峰的能源,是以后研究的方向。     

多级磁力线重接炮的控制与速度测量

重接炮是利用磁力线重接而对弹丸产生推力的电磁发射形式.多级重接炮的关键就在于各级能量的有序释放.本文介绍了重接炮的工作原理,设计了一套多级重接炮的发射控制方案和速度测量系统.以一个自制的三级重接炮系统为基础,实现了其系统控制和速度测量,获得了发射过程中的速度数据及其曲线.对本系统而言,当储能电容器组充电电压为3500 V时,160 g弹丸的发射速度可达24.991 m/s.     

基于地电波幅值经验累积分布特性的高压开关柜状态判断及运维策略

目前国内各运行单位均采用国外经验判断高压开关柜的局部放电情况,缺乏本地化的开关柜状态判断方法。为此基于广州地区30773组在运高压开关柜的局部放电数据,获得了高压开关柜局部放电地电波现场测试值的经验累积分布函数。比较了广州与国外高压开关柜局部放电地电波测试值的经验累积分布函数典型特征的差异。根据25%、10%及5%划分依据,国外某数据库中对应的经验阈值分别为19dB·mV、29dB·mV、35dB·mV,而广州地区数据库中对应的经验阈值分别为13dB·mV、23dB·mV、32dB·mV,表明以国外数据库的分布规律获得的开关柜局部放电地电波测试值判断经验不完全适用于本地区。基于经验累积分布函数,综合考虑了设备的故障风险概率和运维成本等因素,提出了更加灵活、技术经济效益可靠性更优、更加符合本地区的高压开关柜状态判断原则及运维策略。     

基于模拟试验的SF6电气设备低能量放电形式的特征气体

和电弧放电释放的能量相比,火花放电和电晕放电能量较低.对于低能量的放电,在其造成严重危害前,有必要对其类型和状态做出判断.笔者归纳前人对于SF6在不同放电类型下的分解机理,设计模拟试验,使用针板电极和板电极上放有金属碎屑的球板电极分别模拟电晕放电和火花放电,通过分析气体分解产物的类型和体积分数,提出使用S2OF1o的增...