变压器运行中出现的故障与维护措施

电力变压器是电力系统中最重要的电气设备之一,其运行状态直接影响系统的安全性水平.及早发现变压器的潜伏性故障,保证变压器的安全运行,是电力部门关注的一个重要问题。因此,研究变压器运行中出现的故障,提高变压器的运行维护水平,对电力系统的安全运行具有重要的现实意义。     

变压器差动保护及抑制措施探讨

变压器作为交流电力系统重要的电气设备，其正常运行直接关系着系统的安全。差动保护作为变压器主保护，励磁涌流是影响其正确动作与否的关键因素之一。文章分析了变压器励磁涌流及其特点，以单相变压器为例，分析了励磁涌流产生的机理，并给出了常见的抑制措施。     

浅谈变压器气体继电器的应用

电力变压器是电力系统中不可缺少的重要设备，它的故障给供电可靠性和系统的正常运行带来严重的后果，同时大容量变压器也是非常贵重的元件，因此，必须根据变压器的容量和重要程度装设性能良好的、动作可靠的保护装置是变压器安全运行的关键。     

浅谈配电变压器损坏的原因及措施

变压器是输配电系统中极期重要的电器设备，与其它电器设备相比其故障率极低，可一旦发生故障，将给社会生产带来严重的损失，为保证变压器安全正常运行，笔者给合多年工作经验，分析了变压器损坏故障的成因，并提出了防护措施。     

油浸式电力变压器绝缘故障分析

油浸式变压器中绝缘系统的固体绝缘材料老化，严重影响变压器的运行寿命。因此通过各种分析对变压器绝缘系统的影响并提出预防措施，对确保变压器的安全稳定运行有着重要作用。     

基于变压器油的运行维护问题探索研究

本文首先概述了变压器油质量的简易判断和对变压器油运行的要求，然后深入的阐述了变压器油的运行维护问题。变压器作为电力系统中非常重要的设备之一，保证其安全稳定的运行具有极其重要的意义。     

变压器在线监测的应用分析

变压器是电网中比较昂贵且重要的电气设备，其安全运行对于保证电网安全可靠运行意义重大。因此对变压器运行状态进行实时或定时的在线监测具有非常重要的意义，本文从在线监测的原理、重要性、方法及存在问题等方面对变压器在线监测技术作一介绍。     

基于变压器风冷系统故障分析与处理的分析

变压器，尤其是大型变压器的风冷系统，出现故障的频率很高，风冷系统不能正常地为变压器降温，这严重的影响了变压器的运行效率及安全可靠性。为降低风冷系统出现故障的频率，提高变压器的运行可靠性，文章分析了风冷系统出现故障的主要原因，以及对变压器产生的主要影响，最后提出相应的解决策略。     

浅析变压器的事故预防

变压器是电力系统的一种重要的运行设备。电网的安全运行的好坏很大的程度上是由电压器的性能和稳定决定的。变压器的安全稳定的运行是电力系统的安全运行的前提。但是在实际的使用过程中,变压器的运行事故还是存在的。本文针对电网系统中的变压器运行中的事故,来分析和阐述变压器在运行中的事故的预防和处理办法。     

试论变压器在线检测与故障诊断

电力变压器是输配电网络的重要设备之一，其能否安全稳定运行，直接关系到电力系统的稳定性。本文笔者探讨了变压器在线检测与故障诊断。     

磁浮轨检车横向振动及其对磁浮轨道几何参数测量精度的影响

磁浮轨检车是用来检测磁浮轨道几何参数,保证磁浮列车安全运行的轮式特种车辆。建立了磁浮轨检车横向振动二自由度模型,研究了在磁浮轨道随机路面激励下横向振动幅值的大小及其对激光三角法测量磁浮轨道几何参数精度的影响,结果表明该影响在所要求的测量精度范围之内。     

短路冲击下变压器绕组状态在线诊断

在线实时检测变压器绕组状态,对保障变压器正常运行尤为重要.绕组的振动信号能反映出绕组的状态,而这些信号能通过布置在变压器箱体上的加速度传感器测量到.通过对某大型变压器短路冲击实验的在线实时检测,利用振动烈度和基于时频分析的方法对变压器绕组的振动信号进行分析.研究表明,与常规电抗法检测相比较,用时频分析方法能更明确反映出变压器绕组的故障特征.     

地表水源热泵若干常见问题分析

总结了地表水源热泵的主要优缺点及其在推广应用中由于水源原因引起的诸多问题，分析了引发这些问题的各种原因，得出：为使地表水源热泵系统稳定高效运行，重要的是控制好水源的水温、水量和水质。针对各种问题也相应地给出了一些建议。     

Influence of Resistance Method on Motor Winding Temperature Rise Measurement

The objective of this article is presentation of influences when measuring the motor winding temperature rise in the scope of safety testing of electrical appliances, with respect to conformity assessment. The temperature measurement in testing is one of the most defined fields of measurement, but it is very important how the measurement is performed. Standards only describe that the resistance method shall be used for determination of the temperature rise (heating) of the winding. The temperature rise is defined as the average temperature rise of the windings above the ambient (surrounding) temperature, at the specified load of the unit under test. It is not explicitly defined how to approach this measurement when using cooling characteristics of the winding for determination of the temperature rise. Since the extrapolation curve is used, the procedure is also very important to obtain a result as accurate as possible. It is important that measurement results and their associated uncertainties are correctly evaluated, and on that basis, appropriate conclusions of conformity of the product with specifications are made. The resistance method influence on the motor winding temperature rise measurement is a case study in this article. The article focuses on the measurement of the temperature rise of electrical motors used in electrical appliances according to the standard EN 60335-1, clause 11 (2002) (identical as standard IEC 60335-1, 2001). In this article, the influencing parameters are analyzed when measuring the temperature rise of electromotor winding. As a case study, concrete measurements are presented. The optimal time after which the performer has to start measurement of the cooling characteristics is analyzed, since the motors are typically mounted deep into appliances. Especially for a collector motor winding, it takes some time for a performer to be able to connect the measuring instrument to collector??s lamellas because this contact has an important influence on extrapolation results.     

共路激光干涉测量系统的研究

激光干涉测量系统在精密测量领域占有重要地位,它对温度变化、大气变化、激光波长变化、机械安装误差和外界振动等比较敏感,影响系统的测量精度和稳定性。针对此情况,该文提出一种新型的激光干涉光路,两光臂呈完全共路结构,使干涉条纹信号具有极强的抗干扰能力;对光路进行抗干扰分析和理论推导;构建位移测量系统,进行系统测试实验和误差分析。实验表明,本系统测量分辨力0.72nm,合成标准不确定度5．2nm（k=2）,运行速度0．56mm／s,量程0．01mm。     

超声波流量计不同运算方式对比分析

温度漂移是影响超声波流量计测量精度的一个重要因素,本文从算法上提出一种不受其影响的数学模型,以使相应的硬件简单化.该方法已应用在超声波流量计中,收到了很好的效果.     

Investigation of technique for measuring liquid volume under micro-gravity conditions

Measurement of liquid volume under the micro-gravity condition is an important aspect of space technology. In an attempt to create an effective and low-cost measurement system, a Helmholtz resonance technique was applied. Two different liquids were tested. We used water and liquid nitrogen as test liquids, the latter to confirm the applicability of this measurement technique to cryogens. It was found that the measurement technique using Helmholtz resonance is applicable under micro-gravity conditions. However, it was also found that obtaining accurate velocity of sound is important for the measurement. The measurement of spatial temperature distribution in the container is necessary to apply this measurement technique to cryogens because the velocity of sound has strong temperature dependency.     

Development of a System for Temperature Profile Characterization of Baths

Liquid baths are the main calibration equipment to directly affect the measurement uncertainty in temperature calibrations. Therefore, the characteristics of baths need to be well investigated and understood. The temperature profile and stability of liquid baths are one of the most important contributions to the calibration uncertainty of platinum resistance thermometers, digital thermometers, liquid-in-glass thermometers, and thermocouples. Commercial baths only present stability and uniformity data in two dimensions in general; however, thermometers and thermocouples are immersed into the body of the bath, so the depth or z-axis is also very important. In this study, a measurement system has been designed using three-stepper motors and a data acquisition system (DAS). The DAS is developed using object-oriented algorithms to form a three-dimensional (3-D) scanning system. The 3-D scanning system is home-made and used in conjunction with a reference platinum thermometer. The temperature profiles and stability of several types of baths: water, oil, and salt were obtained in the temperature range from 30???C to 450???C. Therefore, this contributed toward a more accurate uncertainty budget evaluation.     

高精密测温电桥的标定与评估

使用RTU和RBC两种精密仪器对中国计量科学研究院中温基准实验室的F900高精密测温电桥进行了标定和评估,分析了不同工作频率、不同输出电流在长杆标准铂电阻温度计测温范围内对测量精度的影响。结果表明:电桥在不同的工作频率下精度的差异比较明显。工作频率为25 Hz时,使用RTU和RBC进行标定的最大测量偏差分别约为0.01 mK和0.06 mK;工作频率为75 Hz时,使用RTU和RBC进行标定的最大测量偏差约为0.08 mK和0.2 mK,且相比出厂时有了较大的漂移。电桥在不同的输出电流下精度的差异非常小,在15 μK以内。采用RTU及RBC对F900测温电桥评价的结果之间相互印证,该结果对中温固定点基准复现过程的不确定度评定提供了数据支撑。     

烧结温度对氧化锆电阻的影响

本文用交流阻抗技术、SEM、EPMA、TEM及正电子湮没技术研究了烧结温度对掺有Al_2O_3的ZrO_2的电阻的影响.电阻的测量结果表明,随烧结温度升高,ZrO_2的晶界及总电阻逐步下降,进一步的研究揭示了产生这种现象的原因.随烧结温度升高,试样中Al元素逐步偏析于ZrO_2晶界,并在晶界上形成高缺陷浓度的晶界相,这就是试样中电阻降低的原因。