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第三烧结厂两台5600kW同步电动机采用热变电阻实现软起动,降低电机起动电流(不超过电机额定电流的3.5倍),延长电机的使用寿命,缩短电机的起动间隔时间,具有明显的经济效益。 相似文献
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金岭铁矿选矿厂采用频敏变阻器取代球磨电机的生铁电阻,在原控制线路基础上进行技术改造,改进了球磨电机的起动方式,改善了球磨电机的起动性能,同时节约了成本。 相似文献
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介绍19000kW大功率电机降压起动原理、热变电阻工作原理和起动特性,分析影响电机起动性能的主要因素;通过起动实践和录制起动曲线,了解热变电阻的实际温度、电网电压等参数对电机起动过程的影响,以期合理地调节参数,优化起动曲线。 相似文献
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通过对我厂原初轧主电机的使用分析,提出采用YDQ液体电阻起动器替代频敏变阻器的起动方式。实践证明,采用该产品后改善了主电机的起动状况,维护方便,运行可靠,完全能满足轧钢系统的要求。 相似文献
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制氧站大型电机起动方式简介 总被引:1,自引:0,他引:1
结合两座新建的制氧站工程,简要介绍了制氧站大型电机用电的特点及其常用的几种起动方式,并对制氧站大型电机的几种起动方式的优缺点进行了比较。 相似文献
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为解决电源容量受限情况下大功率电机离线检修试车问题,用降压起动与辅助起动相结合的方法,同时采用高压并联电容器(带电抗器)补偿的方法来解决起动冲击电流问题;设计了一套负压回油系统解决了轴瓦润滑问题;进行了基于Matlab/Simulink系列仿真试验研究,取得了良好效果,并成功进行了YKS5603—4-W电机试车。 相似文献
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同步电动机通常采用异步起动,当电机转速达到亚同步速以后,投入励磁电流,牵入同步运转。但是,采用这种起动方法,起动电流大,尤其大容量电机起动时,对供电电网的干扰很大,甚至无法起动。采用低频同步起动是避免电气、机械方面冲击的一种较好方法。可是需要较多的投资,控制和操作都比较复杂,如果多台大型电机公用一套起动装置,低频同步起动的优点就比较显著。 相似文献
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介绍一种新型特种电机──YGD电动机的结构及控制系统的工作原理,通过对运行参数的测试,及与JR型电动机的比较,说明是一种起动力矩大而起动电流小、适用于重负荷频繁起动的电动机。 相似文献
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交流电动机的软起动是一种综合技术,它克服了发鼠笼异步机传统降压起动方式的许多缺点,通过采用软起动器可以实现交流电动机的软起动。本文介绍了交流电动机主要的几种软起动方式以及交流电动机软起动的特点,并指出了软起动器的其他一些应用。 相似文献
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Horne Murray R.; Martin Gerard M.; Harley Carolyn W.; Skinner Darlene M. 《Canadian Metallurgical Quarterly》2007,33(2):92
Place learning is impaired when a single plus maze is moved between adjacent locations 33-120 cm apart. This maze translation creates distinct start locations but maintains a single goal location with respect to distal cues. Hippocampal cell recording data suggest the majority of place fields are tied to apparatus boundaries, not to distal cues, when an apparatus is moved these distances to the left or right. Thus, rats may fail to appreciate the existence of multiple start locations with respect to distal cues when the maze is moved in this way and their start location on the surface is constant. Performance on the single plus maze problem was improved when texture cues were correlated with different start locations. Place learning was supported when multiple start locations were provided on a single large surface (double plus maze), even though rats did not explore the entire surface. Place learning was also supported when random extensions were added to a double plus maze such that start locations, relative to surface boundaries, were not informative as to goal location. This outcome suggests sensitivity to multiple start locations is required for distal cue use in translational place problems. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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通过工业试验,探索开轧温度和吐丝温度对82B性能的影响。综合分析确定了合适的开轧温度和吐丝温度使82B性能达到最佳。工业实践表明,开轧温度970-1000℃,吐丝温度860-890℃,82B抗拉强度能达到1200 MPa,面缩率能达到20%以上。 相似文献
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The flagellar gene fliO of Salmonella typhimurium can be translated from an AUG codon that overlaps the termination codon of fliN (K. Ohnishi et al., J. Bacteriol. 179:6092-6099, 1997). However, it had been concluded on the basis of complementation analysis that in Escherichia coli a second start codon 60 bp downstream was the authentic one (J. Malakooti et al., J. Bacteriol. 176:189-197, 1994). This raised the possibility of tandem translational starts, such as occur for the chemotaxis gene cheA; this possibility was increased by the existence of a stem-loop sequence covering the second start, a feature also found with cheA. Protein translated from the first start codon was detected regardless of whether the second start codon was present; it was also detected when the stem-loop structure was disrupted or deleted. Translation from the second start codon, either as the natural one (GUG) or as AUG, was not detected when the first start and intervening sequence were intact. Nor was it detected when the first codon was attenuated (by conversion of AUGAUG to AUAAUA; in S. typhimurium there is a second, adjacent, AUG) or eliminated (by conversion to CGCCGC); disruption of the stem-loop structure still did not yield detectable translation from the second start. When the entire sequence up to the second start was deleted, translation from the second start was detected provided the natural codon GUG had been converted to AUG. A fliO null mutant could be fully complemented in swarm assays whenever the first start and intervening sequence were present, regardless of the state of the second start. Reasonably good complementation occurred when the first start and intervening sequence were absent provided the second start was intact, either as AUG or as GUG; thus translation from the GUG codon must have been occurring even though protein levels were too low to be detected. The translated intervening sequence is rather divergent between S. typhimurium and E. coli and corresponds to a substantial cytoplasmic domain prior to the sole transmembrane segment, which is highly conserved; the sequence following the second start begins immediately prior to that transmembrane segment. The significance of the data for FliO is discussed and compared to the equivalent data for CheA. Attention is also drawn to the fact that given an optimal ribosome binding site, AUA can serve as a fairly efficient start codon even though it seldom if ever appears to be used in nature. 相似文献
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对比分析了4种降压启动方式的原理、特性及应用范围,以及热变电阻、液体电阻降压软启动技术在改善大中型电机启动性能的应用,降低电网的安全风险,最后提出了软启动技术方案应用的考量因素。 相似文献
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