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液氮环境中绝缘材料的沿面闪络对超导电力设备外绝缘设计至关重要,为了揭示液氮环境中沿面闪络的发展过程,并研究有效提高超导电力设备外绝缘爬电距离的方法,通过实验对不同直径的圆柱形、不同倾角的圆台形聚四氟乙烯试品在液氮中微妙级负脉冲电压作用下的沿面闪络电压进行了测量,结果发现圆柱形试品随直径增加,沿面闪络电压下降;圆台形试品在θ=-45°时闪络电压最高,θ=0°时闪络电压最低.通过与真空、绝缘油中沿面闪络的数据比较以及仿真计算,认为液氮中的沿面闪络与变压器和绝缘油中有相似的闪络机制,沿面闪络是在气化的闪络通道内完成的.实验的结果也为超导电力设备外绝缘设计提供了有益的方法. 相似文献
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纳秒脉冲下真空绝缘沿面闪络特性实验研究 总被引:4,自引:1,他引:3
通过实验研究了纳秒脉冲(10/30 ns)下,真空绝缘沿面闪络电压随圆台形绝缘体锥角、圆柱形绝缘体截面直径、实验气压以及电极材料等物理因素的变化趋势,结果表明圆台形绝缘体锥角变化对闪络电压影响非常明显;厚度相同的圆柱形绝缘体闪络电压随截面直径的增大而降低,且直径越小,变化幅度越大;当气压处于高真空范围,即10-5~10-1Pa时,气压变化对闪络电压不构成影响;高真空条件下不同电极材料对闪络电压无影响。并在系统分析实验结果的基础上,提出了真空绝缘结构设计原则。 相似文献
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脉冲电压下尼龙的激光触发沿面闪络特性 总被引:3,自引:2,他引:1
为研究脉冲电压下的激光触发沿面闪络特性,在试验系统中建立了精确的激光触发沿面闪络试验系统,解决了激光脉冲与试品上所加脉冲电压的同步问题,在此基础上应用平板电极和柱状尼龙绝缘材料进行了激光触发沿面闪络试验。试验中采用60 mm直径的铜材料平板电极,试品为20 mm直径、6、8、10 mm厚的尼龙材料圆柱绝缘材料,试验中激光波长为10645、32 nm并聚焦成2 mm×30 mm的长方形光斑,得到在不同的激光能量密度及施加电压下的闪络时延和抖动时间,并探讨了激光触发沿面闪络的机理。研究表明:激光能量密度越大、施加电压越高,闪络时延和抖动时间越小。 相似文献
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高压直流断路器的触头在频繁分合闸过程中会由于电弧烧蚀和机械磨损等原因而产生铜微粒,铜微粒会沉积在断路器断口环氧树脂表面,并显著降低其沿面绝缘性能。针对上述问题,搭建了试验平台,研究了直流电场下铜微粒粒径和位置对环氧树脂沿面闪络电压的影响规律;基于COMSOL Multiphysics建立了环氧树脂非平衡态等离子体沿面闪络模型,分析了铜微粒粒径和位置对沿面闪络电压的影响机制。研究结果表明:附着铜微粒会显著降低环氧树脂沿面闪络电压,铜微粒紧贴高压电极表面时,沿面闪络电压随铜微粒粒径的增加而下降;铜微粒位置亦会对环氧树脂沿面闪络电压产生影响,铜微粒与电极间距越小,沿面闪络电压下降就越明显;铜微粒粒径和位置的变化改变了初始放电发生过程和正负流注头部最大电场强度,进而改变了环氧树脂沿面闪络电压。上述研究结果可为解决高压直流断路器中铜微粒引起的沿面闪络问题提供参考。 相似文献
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《高电压技术》2015,(12)
为了研究真空沿面闪络实验结果的有效性问题,搭建了1套MHz猝发多脉冲平行平板型真空沿面闪络实验平台。利用示波器记录的电压信号、像普通电荷耦合元件(CCD)和像增强型电荷耦合元件(ICCD)相机记录的光学图像、绝缘体表面放电痕迹、电极表面放电痕迹等信息,对实验系统的高压放电现象进行了综合诊断并对实验系统进行了调试。诊断和调试结果表明:该实验系统在高压运行时除了有绝缘子沿面闪络外,还有绝缘隔板放电、水电阻表面放电、绝缘子体击穿和真空电极击穿等放电现象,这些放电现象用某单一的诊断信息来判断是不容易区分的;改进后的沿面闪络实验系统在圆台形绝缘子实验中仍然有9%的几率发生真空电极击穿。分析认为这是由于在击穿场强较高的沿面闪络实验系统中,真空电极击穿场强与绝缘子的沿面闪络击穿场强处于同一数量级所致,这是击穿场强较高的沿面闪络实验系统中存在的普遍问题。综合各种诊断信息,确认沿面闪络实验结果的有效性对于沿面闪络实验研究是十分必要的。 相似文献
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实验研究了纳秒脉冲(10/30ns)下圆台形绝缘体真空绝缘沿面闪络特性,结果表明锥角变化对闪络电压影响显著,45°锥角时闪络电压最高。与圆柱形绝缘体相比,脉冲电压下,±45°圆台形绝缘体闪络电压增幅较大,且脉宽越窄,增幅越大;直流和交流电压波形下,圆台形闪络电压增幅较小。分析认为,45°锥角时阴极三结合点处电场减弱幅度最大,初始场致发射电子数量受到抑制,电子沿绝缘体表面的倍增过程较难实现。预闪络期间直流、交流电压下正离子有时间积累起足够多的能量参与碰撞电离。而纳秒脉冲闪络过程中正离子数纳秒时间内积累起的能量非常有限,作用忽略不计。闪络电压与电压随时间的上升速率有关,纳秒脉冲电压上升速率极快,对应放电时延的电压增幅较大,因此纳秒脉冲闪络电压高于其它电压波形。 相似文献
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为了更加深入地了解换流变压器中交直流叠加电压下油纸绝缘的沿面闪络问题,通过搭建直流电压分量可以任意调节的交直流叠加电源系统,研究了具有背面电极和不具有背面电极这2种结构下油纸绝缘的沿面闪络问题。试验结果表明:在复合电场下,有背面电极时,沿面闪络电压比无背面电极时稍低;在2种结构下,沿面闪络电压均表现为纯交流电压时最低,随着直流电压分量的增加,沿面闪络电压也逐渐增加。此外为分析油纸绝缘界面的影响,还研究了相同电极结构下纯油的击穿电压。对比分析纯油的击穿电压和油纸绝缘的沿面闪络电压后发现:直流电压分量较低时,油纸绝缘界面的存在降低了该结构的击穿电压;而直流电压分量较高时,油纸绝缘界面的存在反而稍微提高了该结构的击穿电压。最后从复合电场分布的特点出发,分析了不同直流电压分量下油纸绝缘的沿面闪络过程。分析后认为:直流电压分量较小时,电极附近电场强度较高,导致油易于电离并产生大量载流子,从而促进了油纸沿面闪络的发展;而随着直流电压分量的变大,电场分布将变得不同,其沿面闪络电压升高;同时,上述电场分布的特点也是造成直流电压分量较低时沿面闪络电压低于纯油击穿电压的原因。 相似文献
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Rui Liu Xinxin Wang Xiaobing Zou Naigong Zeng Luya He Xiao Liu 《Dielectrics and Electrical Insulation, IEEE Transactions on》2007,14(4):889-893
The load section of a pulsed power generator for X-pinch was designed. It is a work that repeats itself in cycles as follows: making small changes in size and configuration of the electrode system in order to reduce inductance rarr calculating the inductance rarr calculating the load voltage with the measured forward going voltage wave along the pulse transmission line (PTL) incident upon the load rarr calculating the electric field rarr checking if any surface flashover or breakdown in vacuum happens. In the final designed load section, the highest field on the surface of the insulator, a plexiglass diaphragm, is 113 kV/cm and the highest field in vacuum is 298 kV/cm, respectively lower than the surface flashover voltage and the vacuum breakdown voltage in case of an applied pulse voltage of 100 ns of full width at half maximum (FWHIVI) and 500 kV in amplitude. 相似文献
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Ping Yan Tao Shao Jue Wang Wei Gao Weiqun Yuan Ruzheng Pan Shichang Zhang Guangsheng Sun 《Dielectrics and Electrical Insulation, IEEE Transactions on》2007,14(3):634-642
Based on a Marx generator and a coaxial pulse forming line, an experimental investigation of surface flashover characteristics in vacuum is conducted by using nanosecond pulses of 10 ns rise time and 30 ns full width at half maximum (FWHM). Insulator dielectrics chosen for this investigation are Teflon, PMMA and Nylon. The tested factors include gas pressure, cone angle of conical frustum, diameter and length of cylindrical insulator, material and shape of electrode, and contact style between insulator and electrodes. The effects of these parameters on the surface flashover characteristics are described and analyzed in this paper. In addition, the character of flashover time lag in the nanosecond range, and surface flashover theory in vacuum charged by nanosecond pulses are also discussed. 相似文献
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The creeping flashover voltage–time characteristics for the composite insulating configuration by insertion of a barrier between a needle electrode and a plane electrode in N2 gas have been investigated. A maximum creeping flashover voltage of around 10 µs has been found in N2 gas for negative polarity. This anomalous voltage–time characteristic is associated with the low field relaxation effect of the accumulated charges on the barrier for an applied pulse voltage with a highly steep wave front. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 146(1): 1–8, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10249 相似文献
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采用光学方法研究陶瓷绝缘材料的沿面闪络特性 总被引:2,自引:2,他引:0
对比研究了真空中交流电压下采用和未采用真空溅射金属电极的氧化铝陶瓷材料,在沿面闪络发生前不同的表面发光特性。基于固体的能带理论,提出了2类试品在金属电极-介质的界面处不同的能量状态分布模型;并在此基础上同时考虑电荷注入复合和场致电子发射对发光的影响,解释了2类试品发光的差异性,指出了采用和未采用真空溅射金属电极的氧化铝陶瓷存在不同的沿面闪络起始机理及发展过程。 相似文献
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Sudarshan T.S. Li C.R. 《Dielectrics and Electrical Insulation, IEEE Transactions on》1997,4(5):657-662
In order to determine the influence of intrinsic material properties of dielectric materials on high field surface flashover characteristics in vacuum, it is important that we minimize or eliminate the influence of the experimental test structure on the high field processes. In this paper we shall examine the flashover characteristics of polycrystalline alumina insulators, using a lateral test structure similar to the one used in semiconductor devices. A significant improvement in surface flashover strengths (~200%) was found using a metalized contact electrode system compared with a classical solid electrode system. The results indicate that, using a metalized film cathode, the scatter in the flashover data is significantly reduced compared with the solid electrode system, implying that the electron-dielectric interaction processes that lead to flashover occur in a more predictable fashion. The new metal contact electrode system reveals the dependence of flashover strength on the surface preparation and the grain size of the dielectric material. The average flashover strength increases and the scatter in the flashover data decrease with a decrease in the average grain size of the particles composing the alumina ceramic. Thus the surface flashover processes in vacuum are related to the dielectric surface microstructure, specifically the surface and sub-surface microdamage and grain-boundary defects 相似文献
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The flashover voltage with a backside electrode was found to be lower than that without the backside electrode. Under microsecond pulse voltage application, we describe the characteristics of a creeping discharge developed in the narrow gap with the backside electrode. Using a CCD camera and ultrahigh‐speed camera, we observed the corona extension processes. The lowest flashover voltage was found to be obtained at positive polarity with a SF6 content D = 3%. In the corona extension obtained using an ultrahigh‐speed camera, peculiar differences were observed in the corona extension process. The corona extension increased, and rapid flashover was observed at D = 3%. Using a CCD camera, small coronas were detected from the backside electrode. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 158(2): 31–38, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20431 相似文献
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