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     

气压对发电机定子线棒端部电晕放电特性的影响(英文)

According to the mechanism of corona discharge at the end of the generator stator bar,a model of stator bar end corona discharge is presented.In a closed corona cage at low atmospheric pressure,the corona discharge characteristics of the stator bar end model were observed using an ultraviolet imaging instrument and an oscilloscope.The influence of atmospheric pressure on the corona inception voltage and discharge intensity was analyzed.The results show that the corona inception voltage is lower under lower atmospheric pressure;the discharge intensity is stronger under lower atmospheric pressure.The particles swarm-optimized support vector machine was employed to analyze the impacts of air pressure and humidity on the corona inception voltage.Error between the calculated value of the established model and the experimental value is less than 5%.The established model can be used to calculate the corona inception voltage of the stator bar end model.     

Thermal behavior of small lithium‐ion secondary battery during rapid charge and discharge cycles

The secondary batteries for an electric vehicle (EV) generate much heat during rapid charge and discharge cycles above the rated condition, when the EV starts quickly consuming the battery power and stops suddenly recovering the inertia energy. During rapid charge and discharge cycles, the cell temperature rises significantly and may exceed the allowable temperature. We calculated the temperature rise of a small lithium‐ion secondary battery during rapid charge and discharge cycles using our battery thermal behavior model, and confirmed its validity during discharge cycle at current smaller than the discharge rate of 1C. The heat source factors were measured by the methods described in our previous study, because the present batteries have been improved in their performance and have low overpotential resistance. The battery heat capacity was measured by a twin‐type heat conduction calorimeter, and determined to be a linear function of temperature. Further, the heat transfer coefficient was measured again precisely by the method described in our previous study, and was arranged as a function of cell and ambient temperatures. The calculated temperature by our battery thermal behavior model using these measured data agrees well with the cell temperature measured by thermocouple. Therefore, we can confirm the validity of this model again during rapid charge and discharge cycles. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 157(3): 17–25, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20249 Copyright © 2006 Wiley Periodicals, Inc.     

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     

Localization of a Partial Discharge Source Using Maximum Likelihood Estimation

Analyzing the electromagnetic waves generated by partial discharges is effective to assess insulation degeneration. In this paper, we describe a locating method for a partial discharge source based on maximum likelihood estimation. This method uses the root mean square and the direction of arrival of partial discharge signals which are calculated from measurement data obtained using sensors. This information is integrated using the maximum likelihood method. In this case, only the signals received in a good reception condition are used because the signals affected by multipath effects can decrease the estimation accuracy. This paper considers the case that apparatuses interrupt the direct paths from a partial discharge source to sensors. The capability of the proposed method was confirmed by simulations using the finite difference time domain method. The results include the comparison of performance for the number of sensors and show that this method has enough resolution to detect partial discharge sources. Copyright © 2010 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Evaluation of Humidity Correction Factor of Disruptive Discharge Voltage of Standard Sphere Air Gaps

The humidity correction method prescribed in the existing IEC standard is based on experimental data obtained under absolute humidity between 5 and 12 g/m³. A discussion on the humidity correction method is needed for higher absolute humidity regions, which is experienced during summer in Japan, and also throughout the year in tropical countries. The effect of absolute humidity on disruptive discharge voltages of standard sphere air gaps has been studied experimentally for several years under conditions of natural humidity, between 2 and 22 g/m³. In the cases of a.c. and lightning impulse voltage application, it was found that the existing IEC humidity correction method seems to be proper for most of the gap spacings studied under absolute humidity up to 22 g/m³. Copyright © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

小开距真空间隙放电特性的研究

采用对固定开距的真空灭体室施加电压使其击穿的方法对与多次重燃过程有密切关系的小开距真空间隙放电现象进行了研究,发现该类放电的特征可用冷击穿电压和开距的关系、燃弧后真空间隙热态耐压强度和开距的关系以及放电时高频重燃半波持续数来进行描述。试验发现用铜铬触头材料制成的真空灭弧室具有最高的冷击穿强度、是银碳化钨的三倍、且对线路的参数不敏感。根据能量关系建立的高频重燃半波数模型可对高频重燃持续的时间进行计算。     

空气相对湿度对紫外检测过程的影响

空气的相对湿度是变化很大的一个气象参数,为了能够更为准确地利用紫外检测技术进行放电的定量研究,需要首先研究相对湿度的变化对检测的影响.利用一种具有定量分析能力的紫外检测装置,通过实验分析电晕放电实际放电量与放电光信号之间的关系.实验结果表明二者之间的拟合关系与实验区域空气的相对湿度没有明显的关系,拟合残差处理后得到的归...     

General Nature of Luminous Body Transition Produced by Pulsed Discharge on an Electrolyte Solution in the Atmosphere

A luminous body (LB) was produced by a pulsed electric discharge that initiated at the tip of the cathode and widely propagated on the surface of an electrolyte in the atmosphere. Entire images of the LB transition taken by a high-speed camera are visually demonstrated for the first time. It is indicated that the entire phenomenon of the LB transition can be classified into three sequential processes, regardless of the experimental conditions. It is estimated that the bright and octopus-like discharge, which may act as a source of high-energy ions and atoms, plays an essential role to make the mechanism of LB phenomena clear. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Electric field measurement just beneath a surface discharge by optical‐waveguide pockels sensors

Although surface discharges are one of the principal kinds of phenomena associated with faults in electrical apparatus, they have not yet been fully elucidated. Electric field measurements in and around a corona streamer during the creeping advance of a surface discharge are very helpful in analyzing discharges. Pockels crystals have been used in the optical measurement of electric fields, and an optical waveguide technique has been successfully used to miniaturize the sensors. Electric field measurements are made just beneath a surface discharge with an optical waveguide Pockels sensor installed on a PMMA plate and output signals expressing the development of the discharge are obtained. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 145(2): 28–34, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10185     

Experimental modeling of high-voltage corona discharge using design of experiments

Many studies, both experimental and numerical, were devoted to the electric current of corona discharge and some mathematical models were proposed to express it. As it depends on several parameters, it is difficult to find a theoretical or an experimental formula, which considers all the factors. So we opted for the methodology of experimental designs, also called Tagushi’s methodology, which represents a powerful tool generally employed when the process has many factors to consider. The objective of this paper is to model current using this experimental methodology. The factors considered were geometrical factors (interelectrode interval, surface of the grounded plane electrode, curvature radius of the point electrode), climatic factors (temperature and relative humidity), and applied high voltage. Results of experiments made it possible to obtain mathematical models and to analyse the interactions between all factors.     

覆冰棒板间隙直流电晕放电试验及测量

研究结果表明,在带电情况下覆冰绝缘子表面冰棱并未完全桥接,在覆冰绝缘子串两端的伞裙之间存在一定的空气间隙。为了研究这种空气间隙对放电发展的影响,提出了冰棒-冰板空气间隙模型。设计了紫外线成像仪CoroCAM IV+和基于虚拟仪器LabVIEW相结合的电晕测量系统。通过对冰棒-冰板空气间隙电晕放电脉冲的测量,证明该测试系统性能良好,能够满足试验测试要求。同时为下一步深入开展覆冰电极系统内空气间隙电晕放电的机理研究提供了试验平台。     

应用粒子群优化算法的静电放电模型参数辨识

为了获得精确的静电放电模型,提出了一种应用粒子群优化算法的静电放电模型参数辨识新方法。以Heidler雷电流方程的静电放电模型参数为辨识对象,分别以仿真及实验数据验证了该方法的可行性,并从电流波形的整体和局部两方面对拟合效果进行了评估。结果表明,与遗传算法相比,粒子群优化方法的执行速度更快,所得的辨识参数精度更高,粒子群优化方法对电流波形的整体和局部关键点的拟合度均高于遗传算法。因此,粒子群算法较遗传算法更适用于解决静电放电模型参数辨识问题。此外,从实例可以看出,粒子群算法不需要过多的初始参数值先验知识,而只须提供一个较宽的初始参数搜索范围即可获得良好的辨识结果。     

水中脉冲电晕放电等离子体特性及气泡运动

介绍了为研究大间距水中脉冲电晕放电建立的放电模型和实验系统。理论和实验结果分析证明水中电晕放电为过阻尼过程,无振荡,无二次放电。采用高速摄影仪研究放电及气泡的运动过程发现,放电仅在高压电极端部形成球形等离子体,不存在贯通的电弧通道,产生的气泡无二次涨缩过程。     

电晕放电辐射信号特征研究

在背景噪声研究的基础上,利用放电针对电晕放电辐射信号进行了实验研究。分析了不同因素(包括不同极性和大小的电压、天线的极化方向、接收距离、放电针的形状、温湿度等)对电晕放电辐射信号波形和频谱的影响。实验表明,电晕放电辐射信号波形具有陡峭的前沿,上升时间从几纳秒到二十几纳秒;频谱成钟型连续谱,主要集中在20~100MHz;极性不同,信号波形不同;电晕放电辐射场一般为垂直极化;辐射强度与接收距离成反比关系;相对湿度不同,信号幅值不同。     

Generation and control of electrolyte cathode atmospheric glow discharge using miniature gas flow

Stable electrolyte cathode atmospheric DC glow microdischarges were generated by using a miniature helium gas flow from a nozzle electrode in air. We developed two schemes to control the temporal evolution of the discharge and the interaction between the discharge column and the ambient air. The vaporization of electrolyte solutions takes place and affects the discharge characteristics. This takes time from the start of the discharge. Therefore, the discharge was controlled by applying pulse‐modulated DC voltages. If the voltage was dropped down to zero before the vaporization, the gas discharge developed without the ionization of the solution components. A helium gas discharge without air developed when the nozzle electrode was placed in a glass capillary. This was confirmed by examining the change in pH of the solution, which usually decreased owing to the generation of nitrogen oxides in the discharge in air. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 178(4): 8–15, 2012; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21222     

正极性电压下空间电荷对空气间隙放电击中点的影响

人们对空间电荷对放电过程的影响研究较少,但很多试验现象体现了空间电荷的作用。为了研究空间电荷对放电击中点的影响,建立了试验平台,并用高速摄像机观测了放电现象。正极性直流与雷电冲击联合加压试验与正雷电冲击电压试验,体现了预加直流电压产生的空间电荷对放电击中点的影响;正极性操作冲击电压试验,研究了不同电压幅值下放电击中点的变化。试验结果表明：正极性雷电冲击电压下,预加直流在针电极附近产生的空间电荷对空间电场的畸变作用不显著;在正极性操作冲击电压下,随着电压幅值的增加,空间电荷对针电极头部电场的屏蔽作用有所提高,放电点远离针电极头部的距离加大。     

Development of a positive creeping discharge along an aerial insulated wire

In high‐voltage aerial distribution systems, the insulated cables are supported by the binding wire with the post insulator at the utility pole. When a lightning strike occurs in the neighborhood of the insulated cable in an aerial power distribution system, inductive lightning surges invade the central line of the cable. Then, creeping discharges develop along the cable surface from the binding wire tip at the same time as flashover of the post insulator at a supporting point of the cable. If the cable insulator has weak points such as pinholes, a malfunction near the cable supporting point may occur, with melting of the wire due to punch‐through breakdown. To prevent such accidents, it is important to clarify the mechanism of the creeping discharge along the insulated cable caused by the lightning strike. The polarity of creeping discharges depends on the polarity of the inductive lightning surges, and the extension length and aspect of the discharge differ greatly depending on the discharge polarity. The development of these creeping discharges is attributed to complicated behavior of the positive and negative electric charges. In the present study, we examined in detail the development of a positive creeping discharge along a wire surface by using a high‐speed image converter camera. This paper describes the mechanism of development of a positive creeping discharge based on the experimental results. 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 173(3): 20–29, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20997     

Fundamental study for assessment of surface resistivity based on waveform characteristics of partial discharge

The partial discharge (PD) waveform reflects the evolution process of electron avalanche in the discharge space. The authors expect to estimate the condition of the discharge space based on the PD waveform characteristics. The semi-conductive sheet was attached to the insulator to simulate the decrease in surface resistance due to deterioration. With the reduction of the surface resistivity, the shoulder appeared on the rising part of the PD waveform and the rise time of the PD waveform became longer. In addition, we simulated the change in the rise time using an equivalent circuit model. The displacement current was calculated from the surface potential distribution estimated by the diffusion equation, and the PD current was simulated by summing up all the current components. As a result, the shoulder was reproduced at the rising part of the PD waveform in the simulation as well. The surface resistance was estimated from the PD waveform by fitting with the experimental results.     

GIS绝缘子表面固定金属颗粒沿面局部放电发展的现象及特征

为研究气体绝缘全封闭式组合电器(gas insulated switchgear,GIS)设备中绝缘子表面固定金属颗粒沿面局部放电发展的现象及其特征,搭建了一套220 kV GIS设备沿面放电缺陷发展实验平台,采用逐步升压法对绝缘子表面固定金属颗粒的沿面局部放电进行长期试验,观察到了放电起始、发展直至沿面闪络的现象。利用测量到的局部放电随时间变化的趋势图、散点图、二维柱状图、灰度图,描述了沿面局部放电发展的现象并获得了相应的图谱特征。试验结果表明:GIS设备绝缘子表面固定金属颗粒沿面局部放电发展现象呈现出电晕放电、电晕放电和沿面流注放电共存、沿面流注放电3个主要阶段。