高压电容器直流局部放电指纹的探索性分析

直流局部检测的意义重大,其数据分析也是很关键的。针对高压电容器直流局部放电测试中的离散数据和有限的数据量,本论文借助统计理论,探索性地选截尾均值进行数据前处理,然后根据统计量的物理意义,对前处理的数据进行峰度、偏度、相关度、变异度等参量提取,探索到不同性能的电容器其指纹参量具有一定的可比性,试尝找到同各类型的高压电容器在绝缘性能上的个体差异,这对以后的深入研究有很大的参考价值。     

碳基电化学双层电容器及复合电源系统的研制

碳基电化学超电容器作为一种新一代储能系统具有广泛的应用。多种测试及研究手段表明本文制备的炭材料具有适合电化学超电容器用途的特殊结构和型貌。直流充放电、循环伏安以及交流阻抗等实验显示了使用该材料组装的电容器具有良好的电化学性能，活性物质的比容量为168．5F／g，在大功率充放电条件下的活性物质的能量密度＞5.0Wh/kg,同时具有10^5以上的循环寿命，脉冲放电实验证明超电容器能有效改善镍氢电池的大电流脉冲放电性能。     

脉冲电压下局部放电对聚酰亚胺膜寿命的影响

本文研究了方波脉冲电压下不同频率、电压和温度下的局部放电行为及对聚酰亚胺薄膜寿命的影响.通过连续高压脉冲下的绝缘老化试验和测试系统,以聚酰亚胺薄膜为试验对象,研究不同脉冲幅值、频率及温度下的局部放电特征和影响因素,并得到其寿命曲线,分析了局部放电参量和寿命间的联系,得到了基于连续高压脉冲下的绝缘老化寿命模型的相关参数.     

浅析变压器的局部放电

为了考核变压器在长期运行的可靠性,产生了局部放电量考试的标准,本文通过对局部放电机理的分析解释,并说明它对变压器绝缘的侵蚀的危害,以至于影响变压器的寿命,结合本人实际工作经验,提出控制变压器局部放电量水平的办法。     

局部放电测量仪校准方法研究

局部放电是一种危害性极大的放电现象,这种放电会极大的损坏高压电力设备的绝缘性能,导致高压设备存在严重的安全隐患。目前,高压设备的生产单位基本上采用局部放电测量仪进行局部放电的测量,但国家尚未出台局部放电测量仪的检定或校准规范。文章通过对局部放电测量仪工作原理的分析,并结合与局部放电测量仪在工作原理上有类似性常见测量仪器——示波器的校准方法,深入探讨和研究了局部放电测量仪的校准项目和校准方法的实施。     

电子管扩音机产生交流声的原因及检修方法

扩音机产生交流声故障的原因1.直流高压整流电路中,整流管半边损坏或电源变压器半边绕组断路,使全波整流变成半波整流,直流输出电压纹波增大。2 .滤波电路中,滤波电容器失效、断路或容量过小,滤波扼流圈短路或局部短路,使直流电源滤波不良,引起交流声。3.退耦滤波电容器失效或开路,滤波电容器和退耦电容器接地点不当,也会产生交流声。4 .扩音机放大管灯丝供电绕组通地电路开路,或灯丝电路中交流声平衡调节电位器调节不当,均会产生交流声5 .放映扩音机多将前置放大级(第一电压放大级)和光电管工作电路用铁质屏蔽罩加以屏蔽。如果屏蔽罩通地不…     

新型氧化镍超电容器电极材料的研究

使用传统的水解方法制备了氢氧化镍胶体,在300℃下进行热处理后得到具有特殊材料微结构以及表面特性的超细氧化镍材料,电化学方法证明该材料制备的电极具有典型的电容性能,“准电容”比容量达到240F／g以上,优于普通的双电层电容器活性炭电容材料比容量。本文首次提出了电容器的正负极采用不同材料的新技术,有效的解决了电容器工作电位范围相对较窄的不足,并且明显的改善了电容器的大功率放电特性,是一种极具有发展潜力的储能器件。     

基于交流放电的UPS电源蓄电池性能测试方法研究

蓄电池性能测试常用直流放电测试方法,所采用的直流放电测试负载对蓄电池的配置数量有一定要求,因而缺乏通用性。利用UPS电源输出交流电的特性,提出了基于交流放电的UPS电源蓄电池性能测试方法。通过详细分析该方法的原理并进行试验,结果表明,该方法适用于不同蓄电池配置情况下的UPS电源蓄电池性能测试,具有较好的经济性和通用性。     

10kV开关柜局部放电综合诊断方法研究及应用

对于10k V开关柜局部放电综合诊断,主要包括内部局部放电、表面局部放电、电晕放电等。其中,采用的方法主要有地电波检测技术(TEV)、超声波检测技术(AE)和超高频检测技术(UHF)。在检测过程中,因现场环境的干扰,采用单一的检测方法并不能全面、客观、真实的反映设备的运行状况。基于此,综合运用不同检测方法,通过相关软件对测试数据进行专业分析的方法来开展10k V开关柜局部放电综合诊断工作,更能有效反映10k V开关柜接触不良及内部绝缘劣化的问题。本文就对10k V开关柜局部放电综合诊断方法及应用进行分析研究。     

负载金属对复合炭极板电极的电化学性能研究

用高比表面积活性炭作为原料,酚醛树脂为粘结剂,在高温下粘结成型制备固体超级电容器用活性炭极板,用直流恒流循环实验考察活性炭极板电极的电化学性能.在活性炭中负载不同种类金属离子,考察金属离子的电化学性能对活性炭极板比电容的影响.实验发现负载廉价金属Mn、Co、Cu可以增加放电容量,负载金属Mn的电极在700℃炭化时比电容为265 F·g-1.     

Estimation of Parameters of Universal Distribution of Moments of Failure of Products

A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling.     

Evaluation of optical properties of highly scattering media by moments of distributions of times of flight of photons

A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue.     

Estimation of potentialities of methods of summation of direct measurement errors

Conventional methods for summation of direct measurement errors are considered. Conditions under which these methods provide consistent results are stated. It is proposed to utilize for characteristic of the total error, its interval estimator or the half-sum of the value obtained by adding up its arithmetic and geometric random errors.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 10–12, April, 1995.     

Assessment of intakes of mixtures of radionuclides

Australia has several uranium mines and a large number of mineral sand mines, with associated processing facilities. Exposures resulting from these mining and processing operations usually involve intakes of mixtures of radionuclides. This work describes the development of a suite of first order, linear compartment models, based on the ICRP Publication 66 respiratory tract model, and an analytical solution to the decay equations, for assessing the consequences of such intakes. The computer programs based on these models directly compute excretion, organ retention and organ and whole-body doses for intakes of either single radionuclides or any mixture of radionuclides belonging to the same radioactive decay chain. The intake can be via inhalation, ingestion or injection, and can be acute, chronic or of limited duration. The starting concentration and degree of secular (dis)equilibrium can be specified for each radionuclide. No assumptions need to be made about the relative magnitudes of the radioactive half-lives of the different nuclides.     

Determination of parameters of microstructural inhomogeneity of deformation of metals by the method of modeling

The article suggests a method of evaluating the microstructural inhomogeneity of deformation of metals by modeling. The method includes the measurement of deformations of metal according to meshes of a dividing grid with small base and the calculation of the distribution parameters of microdeformations in model representation. It is shown that the modeling method makes it possible objectively to evaluate the microinhomogeneity of deformation of metals independently of the chosen mesh size of the dividing grid. New structural characteristics are introduced: the base and wave of variation expressing the degree of crumbling or amalgamation of metal grains by inhomogeneity of deformation.Translated from Problemy Prochnosti, No. 7, pp. 40–44, July, 1991.     

空压机轴承箱蜗壳温度探头油封改造

由于空压机进气侧轴承箱蜗壳温度探头密封效果不好,使空压机及其后续管道受到油污染。后将温度探头的O形圈密封改为骨架油封,杜绝了轴承箱漏油问题。文章简介空压机的结构和技术参数,详细介绍了骨架油封的制作和优点。     

Characteristics of mechanical properties of materials in studies of conditions of attainment of marginal states

It is shown that conditions of attainment of marginal states in the material of structural components are formulated on the basis of analysis of force and deformation criteria of formation and development of destruction. The parameters of these criteria are data on types of structural materials, standard and special characteristics of their mechanical properties, structural forms of considered elements of the equipment, and their operating stress loading. In this case, the construction of a system of state equations for describing interrelation of current damage, external actions, and responses to them is based on the concept of calculating variations in properties of materials at all stages of the design life cycle.     

Analysis of anisotropy of properties on the basis of studies of texture of coarse-grained ingots of thermoelectric materials

An analysis of anisotropy of the properties of a Bi₂Se_0.3Te_2.7 solid solution was carried out using construction of demonstrative surfaces for thermoelectric effectiveness and thermal expansion coefficients. It is shown that the texture is an important factor forming anisotropy of properties and technological fitness of ingots for manufacturing modules. Anisotropy of properties based on the studies of the ingot textures obtained using the float-zone method and Bridgman method (growing thermoelectric plates in a flat cavity) was studied.