封闭电机用各种复合漆包线的特性

封闭电机用的电磁线通常是聚氨酯改性聚乙烯醇缩醛漆包线、聚酯亚胺漆包线和各种复合漆包线例如聚酰胺亚胺/聚酯复合漆包线和聚酰胺亚胺/聚酯亚胺复合漆包线。特别是复合漆包线,由于它们的很多性能比聚氨酯改性聚乙烯醇缩醛漆包线和聚酯亚胺漆包线的好,目前广泛用于封闭电机。复合涂层法被认为是一种在生产成本方面可以和单涂层法相竞争而能制造出性能更好的漆包线的生产方法。为获得性能比聚酰胺亚胺/聚酯亚胺复合漆包线和聚酰胺亚胺/聚酯复合漆包线好的封闭电机用的新型电磁线,我们制备了各种复合漆包线试样并进行了评定。     

国内外漆包线漆发展概况(摘要)

文中介绍了目前各国使用漆包线漆的品种有:1.聚酯漆包线漆;2.缩醛漆包线漆;3.聚氨酯漆包线漆;4.聚酯酰亚胺漆包线漆;5.聚酰胺酰亚胺漆包线漆;6.聚酰亚胺漆包线漆。并着重介绍美国、法国、联邦德国、日本一些绝缘漆制造厂和产品情况,以及目前漆包线漆     

国内外漆包线的介电谱对比

本文主要叙述进口F级漆包线与国产F级漆包线性能上的差异,通过测试漆包线的tgδ—t℃曲线和耐电压性能,表明进口漆包线的T_1温度比国产的同类型的漆包线高约13％,耐电压水平高约38％,而且国外漆包线性能的分散性明显优于国产漆包线。文章分析了造成国产漆包线性能分散性大的各种因素,并认为测试漆包线tgδ—t℃曲线有利于控制漆包线的质量。     

拉伸对变频电机用漆包线耐电晕性能的影响

为了分析耐电晕漆包线在电机实际使用过程中的耐电晕性能,通过拉力试验机模拟耐电晕漆包线使用过程中的拉伸情况。首先通过拉力试验机对耐电晕漆包线进行拉伸,拉伸率分别为10%、15%。然后分别进行未拉伸漆包线、拉伸率10%及15%的耐电晕漆包线的击穿电压试验和耐电晕性能试验,并进行漆包线拉伸前后击穿电压和耐电晕寿命的比较。结果表明:拉伸率为10%、15%后漆包线击穿电压与未拉伸试样相比略有下降,拉伸15%后漆包线的击穿电压保留率超过85%。拉伸率为10%、15%的漆包线耐电晕性能与未拉伸试样比较有较明显的下降,拉伸率为15%的漆包线的耐电晕性能略差于拉伸率10%的漆包线,耐电晕漆包线拉伸率为10%时,其耐电晕性能保留率不足20%。     

国外复合涂层漆包线发展概况

介绍了近期国外复合涂层自粘性漆包线、复合涂层耐冷冻剂漆包线、复合涂层耐热性漆包线以及复合涂层表面润滑漆包线的种类、性能和发展概况。     

铝漆包线在单相交流永磁同步电机上的应用

U形铁心永磁同步电机定子绕组由两个集中绕组串联连接,原采用环形绕线工艺,使用铜漆包线,线径在0.21 mm~0.40 mm之间。现将铜漆包线绕组改为铝漆包线绕组,经实践技术可行,成本优势明显。文章从铝漆包线电磁方案调整、绕组绕制、铝漆包线褪漆膜、铝漆包线焊接和焊点防腐蚀等方面作了详细介绍。     

发展F级产品提高绕组线行业整体水平

我国聚酯漆包线(B 级)的产量,目前约占漆包线总产量的80%;而世界上主要工业国则以生产 F 级及以上的耐热漆包线为主。新开发的电机绝缘结构和“八五”规划提出的电机电器以 F 级绝缘为主的要求,将促使我国漆包线由 B 级向 F 级加速发展。目前,我国 F 级及以上漆包线漆和漆包线的生产已基本成熟或趋向成熟,也有一定的生产能力,如果抓住制漆原材料的质量和生产供应,形成规模生产,则相应的漆包线漆和漆包线生产也能发展,价格就随之下降,出现良性循环的局面,有利于提高我国绕组线行业的整体水平。     

从国外趋势谈我国漆包线发展中的几个问题

从世界范围各种漆包线漆的市场分析,近十年来聚氨酯及缩醛漆的用量不断下降,聚酯亚胺呈上升趋势;不断提高漆包线的耐热性,扩大改性聚酯或聚酯亚胺/聚酰胺酰亚胺复合涂层漆包线的生产,则是国外的发展总趋势。据此,针对我国目前漆包线生产聚酯占96%左右、停留在 B 级绝缘水平的现状,就调整漆包线产品结构,发展聚酯亚胺漆包线、复合涂层漆包线及彩电用聚氨酯漆包线,限制漆包线及其用漆生产盲目发展等方面,提出了相应的看法及建议。     

基于直流电阻测量的铝漆包线电机快速甄别

根据铝漆包线和铜漆包线的特性不同,通过测量电机绕组直流电阻,提出快速甄别铝漆包线电机的方案,实验和仿真证明该方法准确和简单.     

耐电晕涂层厚度对漆包线耐电晕性能的影响

为了确定耐电晕漆膜厚度对漆包线漆性能的影响,研究了耐电晕漆包线漆组分一定,涂漆方案不同的耐电晕漆包线附着力和耐电晕性能。结果表明:对于1.25 mm三涂层2级漆膜厚度的漆包线而言,底漆厚度0.02 mm、耐电晕漆厚度在0.05 mm以上时,漆包线的综合性能可达到国家标准。     

氮气发生器在绝缘串列线上的应用

在电缆行业中氮气的使用是非常普遍的,铜丝在拉丝过程中会有退火和预热的要求,在这个过程中就需要氮气对铜丝的表面进行保护,以防止发生氧化。氮气发生器是一种可靠的制氮装置,用来分离或生成很清洁的氮气。使用氮气发生器,可以解决很多使用氮气而带来的问题,而且可以降低成本。     

减少水电弃水调峰损失的措施分析

本文通过对几个典型电网弃水调峰情况的调查分析，指出了弃水调峰的原因。并以华中电网为例，分析了近几年电网负荷率、最大峰谷差、火电综合调峰能力及弃水调峰损失电量的变化趋势。文中对如何合理确定水电厂的弃水电量进行了详细的探讨，并从电源结构、运行管理、经济政策、电网调度等方面对减少水电弃水调峰损失的措施进行了初步的探讨。     

Software tools to improve note-taking in the classroom

This paper describes the functionalities and some implementation details of software tools to assist and to improve the process of note taking by students during a traditional lecture. The software tools allow professors to interact effectively with the students during lectures and help students to take relevant notes. They are based on a previously described software, and use a network of pen-based computers as well as a large screen projection system     

Optimization of the operating conditions of fuel oil combustion in the furnaces of large-capacity boilers

We describe a proposed small-size cavitator having an adjustable flow cross-section, which allows the dispersion of water-fuel oil emulsion to be varied during the operation of large-capacity boilers. It is shown that the operating conditions of the boiler must be synchronized with those of the cavitator if we wish the problem of reducing the amount of harmful substances emitted into the atmosphere during the combustion of fuel oil to be solved in a comprehensive manner.     

AgSnO2的断裂机理及裂纹对触点材料侵蚀过程的影响

本文主要研究了AgSnO2触点材料在使用过程中的裂纹产生机理以及裂纹对材料侵蚀过程的影响。     

光伏发电反孤岛效应的方法研究

孤岛效应是太阳能光伏发电并网过程中不可避免的现象,安全隐患很大,必须针对这种分布式电源的特性,采用被动式检测技术或主动式检测技术模式中的某一种方法,快速、准确检测并同时采取反孤岛效应的措施来保证电网、设备及人员的安全。自适应逻辑频率偏移法可以有效解决检测过程中存在的盲区问题。     

Changes in the surface EMG signal and the biomechanics of motion during a repetitive lifting task

The analysis of surface electromyographic (EMG) data recorded from the muscles of the back during isometric constant-force contractions has been a useful tool for assessing muscle deficits in patients with lower back pain (LBP). Until recently, extending the technique to dynamic tasks, such as lifting, has not been possible due to the nonstationarity of the EMG signals. Recent developments in time-frequency analysis procedures to compute the instantaneous median frequency (IMDF) were utilized in this study to overcome these limitations. Healthy control subjects with no history of LBP (n=9; mean age 26.3/spl plusmn/6.7) were instrumented for acquisition of surface EMG data from six electrodes on the thoraco-lumbar region and whole-body kinematic data from a stereo-photogrammetric system. Data were recorded during a standardized repetitive lifting task (load=15% body mass; 12 lifts/min; 5-min duration). The task resulted in significant decreases in IMDF for six of the nine subjects, with a symmetrical pattern of fatigue among contralateral muscles and greater decrements in the lower lumbar region. For those subjects with a significant decrease in IMDF, a lower limb and/or upper limb biomechanical adaptation to fatigue was observed during the task. Increases in the peak box acceleration were documented. In two subjects, the acceleration doubled its value from the beginning to the end of the exercise, which lead to a significant increase in the torque at L4/L5. This observation suggests an association between muscle fatigue at the lumbar region and the way the subject manipulates the box during the exercise. Fatigue-related biomechanical adaptations are discussed as a possible supplement to functional capacity assessments among patients with LBP.     

Optimizing the flame aerodynamics and the design of tangentially arranged burners in a TGMP-314 boiler

Technical solutions for optimizing the flame aerodynamics and the design of tangentially arranged burners in a TGMP-314 boiler are proposed. The implementation of these solutions will make it possible to achieve more reliable operation of the boiler during fuel oil combustion, smaller amount of NO _x emissions during the combustion of gas and fuel oil, and a somewhat lower air excess factor in the furnace.     

The use of electron paramagnetic resonance in the probing of the nano-dielectric interface

Electron paramagnetic resonance (EPR) has been used to study the properties of trapped electrons or holes in XLPE and in 12.5% vinylsilane-treated SiO₂ nano-particles in XLPE specimens. Both electrically unstressed and electrically stressed (up to 25 kV/mm) specimens were used. The EPR spectra of both materials indicated that the acceptors/donors were oxygen radicals in the polymer, probably originating during the cross-linking. It was found that the anisotropic oxygen environments were not randomly oriented, but were textured, presumably during the fabrication of the sheet specimens. It was found that under the action of an applied electric field, the population of an additional number of oxygen radicals occurred. This result is discussed in relation to the implied polymer structure and conductivity mechanisms.     

小浪底水轮机6号机组启动过程对叶片的疲劳损伤估算

小浪底水轮机首台6号机组投入运行6个月后,13个叶片全部产生穿透性裂纹。应用局部应力应变法估算6号机组启动过程对叶片疲劳的损伤,结果表明6号机组在启动26次左右就有可能出现裂纹,得出启动中引起的叶片中过大动应力是叶片开裂的主要原因。