电触点间隙动态特征测量研究

触点作为构成开关电器的主要部件,工作过程中其表面形貌的变化直接影响着开关电器的工作情况。本文利用触点双向拍摄系统,对直径为4 mm的Ag Ni触点进行拍摄试验,实现了每秒50帧、1200×1024像素双向拍摄触点在通断过程的表面形貌。同时,采用MATLAB软件对拍摄系统所得照片进行处理,提取触点边缘轮廓线,分析了触点间最短距离、表面最大凸尖高度随着操作次数增加的变化。结果表明,随着操作次数的增加,触点间最短距离波动减小,触点表面最大凸尖高度波动增高。     

空铁芯电感负载对开关寿命试验影响

为使电器附件开关寿命比对试验条件能较好地符合IEC和GB有关标准要求,建了一套由Labview图形软件监控的空铁芯感性负载无人值守的控制柜装置,比对试验核心是对开关触点电寿命的影响。     

断路器合闸线圈烧毁原因分析与改进

断路器跳合闸线圈烧毁是变电站综合自动化系统在运行中经常出现的问题,结合一起220 kV断路器合闸线圈烧毁事故,对其可能存在的原因进行探讨并初步分析。发现断路器跳合闸线圈烧毁可能由于合闸滚子和合闸掣子长期的摩擦,导致合闸滚子和合闸掣子脱离时的摩擦力增大引起。根据这一原因提出延时跳开合闸回路改进措施,同时对跳闸回路提出改进意见。     

Gas dynamic control of properties of welded joints from high strength alloyed steels

Gas dynamic control in welding with consumable electrode in conditions of two-jet gas shielding and its impact on the processes in the welding area and properties of the welded joints from high strength alloyed steel 30HGSA is considered in the paper. The results of a comparative experimental study of controlling the properties of welded joints by changing the gas dynamics of the active shielding gas are given. The impact force of a shielding gas jet on the drop of the electrode metal is 12 times higher in conditions of two-jet gas shielding than in those of single jet shielding. It is found that gas dynamics of the active shielding gas jet determines the formation of the welded joints, their chemical properties and the properties of the welded joints from high strength alloyed steels. The consumable electrode welding method with two-jet gas shielding provides controlled dynamics in the welding area and allows controlling the transfer of the electrode metal, chemical composition of the weld, stabilizing the welding process, it ensures higher mechanical properties of the welded joints.     

Synthesis,crystal structures and non-bonded S···S contacts with O‒H···O/O‒H···S hydrogen bonds in isomeric hydroxyphenyl-1,3-dithianes

The synthesis of isomeric hydroxyphenyl-1,3-dithianes and the role of sulfur in them to generate different engineered solids based on non-bonded O···S contacts and O?H···S hydrogen bonds are presented. With an increasing number of OH groups and dithiane rings (e.g. 2, 3), the role of O?H···S interactions becomes less prominent and the strong O?H···O hydrogen bonds along with C?H···π and π–π stacking interactions dominate the packing arrangement of the hydroxyphenyl-1,3-dithianes.     

微晶,纳米晶CuCr触头材料的组织及性能

采用机械合金化的方法制备出Ｃｕ－Ｃｒ纳米合金粉并分别在９２０℃，７５０℃及５８０℃将合金粉热压烧结得到微晶，纳米晶ＣｕＣｒ合金。５８０℃热压可以得到致密度大于９０％的钠米晶ＣｕＣｒ块体，７５０℃及９２０℃热压晶粒长大到微米量级。     

镍、铜低合金奥贝球铁特性研究

阐明了含Ni、Cu质量分数分别为1.5%和0.8%的奥贝球铁的凝固/相变和性能特点。测定了凝固过程的微分热分析曲线、膨胀仪曲线、绘制了奥氏体连续冷却较变曲线和等温转变动力学曲线，对比分析了该成分铸铁的淬透性。测定了Ni、Cu合金化奥贝球铁的常温力学性能。     

Understanding the structure of the first atomic contact in gold

We have studied experimentally jump-to-contact (JC) and jump-out-of-contact (JOC) phenomena in gold electrodes. JC can be observed at first contact when two metals approach each other, while JOC occurs in the last contact before breaking. When the indentation depth between the electrodes is limited to a certain value of conductance, a highly reproducible behaviour in the evolution of the conductance can be obtained for hundreds of cycles of formation and rupture. Molecular dynamics simulations of this process show how the two metallic electrodes are shaped into tips of a well-defined crystallographic structure formed through a mechanical annealing mechanism. We report a detailed analysis of the atomic configurations obtained before contact and rupture of these stable structures and obtained their conductance using first-principles quantum transport calculations. These results help us understand the values of conductance obtained experimentally in the JC and JOC phenomena and improve our understanding of atomic-sized contacts and the evolution of their structural characteristics.     

Social contacts and production of 50-kHz short ultrasonic calls in adult rats.

The goal of the study was to provide evidence that the production of 50-kHz calls by adult rats is driven by potential or direct social contacts. The calls have been studied during daily visits to a cage by single or paired rats. Repeated exposure of rats to the cage frequently visited by other rats or direct contact between rats significantly increased the number of 50-kHz calls. The increase in production of 50-kHz calls was reduced by 78% after intrapreoptic-anterior hypothalamic injection of MK-801, an N-methyl-D-aspartate-type glutamate receptor antagonist. Calls emitted in all situations had a similar acoustic profile. It was found that 50-kHz calls were produced in anticipation of, and/or during, direct social contacts among adult rats and were predominantly initiated by olfactory stimuli. The calls seem to express an appetitive behavioral state in which the central glutamatergic mechanism is implicated. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

电器设备组件特别是接线端子容许温升的导则--IEC60943技术报告(一)

IEC60943技术报告是由IEC32熔断器技术委员会编制，并于1998年发布的。技术报告旨在指导评估稳定状态下载流电器设备组件的温升容许值。技术报告提供了触头接触电阻的计算和基本老化机理；触头和接线端予的温度和温升计算；不同组件，特别是触头，接线端子和连接它们的导体的最大容许温度和温升；IEC各产品委员会确定最大容许温度和温升必须遵守的主要程序。