二烧结主排风机变频起动装置及故障处理介绍

本文简单介绍了二烧结主排风机变频起动装置的原理,着重介绍该装置在调试和生产中处理系统过负荷、并网失败、励磁电流振荡及盘车电机起动力矩不足等故障问题的方法。     

POWERFLEX 7000变频器在烧结主排起动装置的应用

在二期烧结工程变频装置改造中,对三种应用于风机、水泵类负荷的高压、大容量变频装置的优缺点进行了比较,确定采用ROCKWELL公司POWERFLEX 7000“B”frame系列变频器.主要介绍POWERFLEX 7000变频器的组成、控制原理以及同步电动机从变频向工频切换控制原理,POWERFLEX 7000变频器在烧结主排风机软启动应用中的调试方法及注意事项.     

大功率变频调速装置在高炉鼓风机起动中的应用

概述了60 MW级同步电动机应用大功率变频装置作为起动装置进行起动的过程,并详细地介绍了该变频装置的工作原理.     

梅钢4号烧结机主抽风机变频软启动系统

介绍一个采用一台西门子GL150型LC I变频器依次启动两台6 900 kW同步电动机拖动的主抽风机的变频软启动系统。变频器的控制方式为转矩控制,启动方式为分段加速,变频软启动系统通过降压变压器-GL150变频器-升压变压器启动10 kV同步电动机。GL150型变频器采用大功率晶闸管元件,变频软启动系统在启动中通过直接检测定子电压、电流来计算转子位置,不需要外置的测速编码器。采用变频软启动方式启动大型高压电动机,避免了传统的不变频异步启动方式必然带来的电动机电枢发热严重的现象。采用GL150型变频器的变频软启动系统,在整个启动-并网过程中对电动机完全可控,对风机无冲击。     

大型鼓风机组同步电动机的变频起动装置

本文介绍了马钢新１＃高炉鼓风机站３２ＭＷ同步电动机变频起动装置的基本情况、主回路及控制系统的工作原理，装置的起动程序、设备结构、冷却方式以及系统的主要技术数据。     

大容量电流型变频装置

本文介绍日本安川电机公司为上海宝钢一号高炉出铁场除尘风机电动机提供的变频起动装置。 除尘风机电动机共4台(一次和二次除尘各2台),3KV、1600KW笼型感应电动机。约每90分钟起动一次,两台风机轮换工     

烧结抽风机驱动电机用变频装置实现软起动

本文阐述了大型交流电动机采用变频装置实现软起动的优点及过程，同时对同步电动机起动的矢量控制进行了分析，展望了大型同步电动机实现软起动的前景。     

高压变频技术在烧结主抽风机上的应用

济钢400m2烧结机主抽风机采用高压变频器起动和变频调速运行,实现2台电机与2台变频器无扰切换、互为备用。系统实现了同步投切、飞车起动、同步机励磁自动调节等功能,节电率超过20%,效益显著。     

多台高压同步电动机液态软起动控制方案

利用液态软起动的原理起动多台高压同步电动机,可以节省投资.介绍了使用Quantum系列PLC实现对多台高压大功率同步电动机起动过程的控制方案.     

软启动器及高压变频器在烧结主抽风机的应用

正梅钢公司4号烧结机设计400 m~2,2009年12月投产运行。主抽系统采用两台西门子同步电动机,功率6 900 kW(1DV1540-8AE03-Z)。按照惯例,大功率风机采用软启动设备启动,启动完成后切换至工频运行。梅钢公司采用了西门子GL150软启动器。原设计采用"一拖二"方案,一台风机启动完成后,西门子GL150软启动器经过"消磁"便可投入到另外一台风机的启动。2011年12月5号烧结机投产运行,主抽系统硬件与4号烧结主抽系统完全     

The effect of amount of possession of the trait of hostility on accuracy of perception of hostility in others.

Some theories of personality hold that an individual's perception of others is influenced by his own personality characteristics; more specifically, that a trait of low social value will be projected more into others, and that insight into the possession of these characteristics reduces this distortion. These 2 hypotheses were tested by having a group of college students rate each other (including themselves) on degree of friendliness or hostility. Agreement with group rating about self yielded the insight score. In general, the hypotheses were supported; the "friendly" Ss were most accurate in their perception of others, and insight was positively associated with accurate perception. From Psyc Abstracts 36:04:4HL16M. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparison of rates of infection of two methods of emergency ventricular drainage

The rates of infection of two methods of external ventricular drainage in use at Atkinson Morley's Hospital--namely, (a) percutaneous drainage with Rickham reservoirs and (b) tunnelled ventriculostomies--were compared in this retrospective review. Percutaneous drainage of CSF with Rickham reservoirs was associated with a 27% rate of infection as identified by positive microbiological cultures; tunnelled ventriculostomy catheters had a 10% infection rate. The difference in the infection rate between the two methods was statistically significant (P < 0.015). Other variables examined, including the age and sex of the patients and the reasons for ventricular drainage, were not associated with an increased rate of infection. Most infections from either method were caused by a coagulase negative staphylococcus. The average duration of ventricular drainage before identification of positive cultures was 5.7 days for Rickham reservoirs and 6.0 days for ventriculostomies.     

浅析《野草》的版画特征

鲁迅先生一生热爱美术作品,对版画中木刻兴趣尤甚.<野草>作为其"写心之作",亦呈现出一些与木刻版画一致的审美特征:一是具有木刻版画的色彩特征,多对比、多冷色,有阴郁的美感;二是具有木刻版画的力度特征,环境描写、人物刻画处处刀锋毕现,遒劲有力,有一种"力之美".     

四辊破碎机车刀架的改造

针对四辊破碎机车刀架车削中存在的几个问题,详细介绍了电动车刀架的结构和工作原理,建立主要设计参数的数学表达式,并进行适当的分析。改造后,这种电动车刀架运行平稳、可靠、方便、省力,取得了预期的效果。     

转炉炉壳热应力分析

根据实际转炉建立实体模型。以有限元为手段,考虑了炉衬和炉壳材料的物性参数随温度变化的特点和炉衬与炉壳之间膨胀间隙,计算了转炉炉壳在温度载荷和炉衬膨胀压力同时作用下的热应力。所得结果可为转炉炉壳设计提供依据。     

Comparison of the results of surgical and conservative treatment of fractures of the diaphysis of the tibia

In this paper is treated the fundamental problematic of the fracture of the diaphysis of the tibia and the therapeutic results after the conservative and operative treatment are confronted. Among 518 patients with 433 open fractures and 35 with closed fractures of the diaphysis of the tibia, successful treatment of more 2/3 was obtained in the period from 1968 to 1972. Following our casuistics and literature, whose results are similar, we find out that the average total treatment of the osteosynthesis of the fracture of the diaphysis was shortened for 2,5 months depending upon the type and the localisation of the fracture. Apolied methods of the operative and conservative and conservative treatment in relation to the velocity of the medical cure as well as to the extreme anatomical-functional results are analised. We noticed that osteosynthesis, made by the intermedullary nail and the extension of the canals or by a small AO table, by the achieved stability makes conditions of immediate motions and an early rehabilitation. Because of that it gives the best functional results.     

Results of treatment of cancer of the cardia

Cancer of the cardia is traditionally discussed with cardiac cancer of the lower portion of the esophagus and upper gastric cancer invading the esophagus, and the specific characteristics of cancer of the cardia have never been clearly defined. We reviewed the outcome of 172 patients with adenocarcinoma of the cardia who had undergone radical surgery between 1949 and 1994 in the Division of Gastrointestinal Surgery of the Cancer Institute Hospital. The centers of the tumors were located within 2 cm above and below the boundary between the esophagus and the stomach, and their longitudinal diameter was less than 8 cm. We divided the patients into an early period (1949-1979; n = 79) and a late period (1980-1994; n = 93), and focused on the historical transition. There were no differences in patient gender or histology between the two periods. However, the late period was associated with fewer cases of esophageal invasion and shorter longitudinal diameter, as the age of the population advanced. The number of advanced cancers such as the localized and infiltrative type had decreased, and early cancer and early clinical stage had become more common, but despite the fact that the number of early cancers had increased, extended dissection, such as thoracic and paraaortic lymph node dissection, was performed more frequently. By clinical stage, the long-term outcome markedly improved in Stage I patient in the late period, and tended to improve in Stage II and III patients. This appears to have been attributable to the prevention of micrometastasis by extended dissection, although the number of early cancers is another major potential cause. There were no differences in the outcome of Stage IV patients between the two periods, and further advances in multimodality therapy must be awaited. The range of resection is basically proximal gastrectomy, and if there are adequate indications, the prognosis is favorable. In view of the status of lymphatic flow and lymph node metastasis, and long-term results, lateroaortic lymph node dissection is important. Since the number of early cancer patients has been increasing, if intraabdominal recurrence is prevented, intrathoracic lymph node dissection will contribute greatly to the outcome of such patients.     

焦炭热性能指标意义浅析

通过对焦炭在高炉内的历程及其变化规律的剖析,阐述焦炭热性能指标的意义,形象地把焦炭在高炉内的损耗分为三部分(M1,M2,M3)。指出M2对焦比及焦炭价格有一定的指导作用。     

参与式农业基地建设行动方案设计

为了编制实用性强的基地建设行动方案,首先,确定参与式发展的主体,搭建一个"决策框架";其次,针对行动目标,提出不同参与主体,如管理者、农民、消费者等团队与个人的目标及行动内容;最后,工作应向重塑伙伴式合作关系,挖掘农民自我发展潜力,完成三大角色的转换,打造农业基地文化等方向推进.