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通过对冷轧厂HC轧机主电动机通风系统改造,彻底解决了电动机风量不足及轧机倒的油雾和含金属粉尘通过主电动机联轴节与通风密闭室隔墙板之间的空隙进入主电动机密闲室,进而进入电动机内,造成油雾和含金属粉尘沉积在电动机电枢绕组、升高片和磁极绕组以及连线上,甚至进入电枢铁芯内侧,不易清理,不仅会降低电动机绝缘寿命,严重时还可能造成大电动机短路放炮事故的发生。 相似文献
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从操作过电压产生机理出发,阐述操作过电压对高压电动机的危害,通过对高压电机在各种情况下操作过电压的探讨分析,指出高压电动机采用传统起动方式存在的问题,分析了高压电动机采用软起动的必要性,通过对当前各种软起动装置的比较,提出了选择依据。 相似文献
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简单介绍了三相异步电动机的原理,选用以及运行中的雏护与保养,重点阐述了三相异步电动机的常见故障及分析,保证电动机的安全运行。三相异步电动机是由定子上的对称三相绕组中通以对称三相交流电流所产生的磁势建立旋转磁场,而旋转磁场与由该旋转磁场在转子绕组内所感应的电流相互作用,产生电磁转矩来实现旋转运动,从而将电能转换为机械能。由于三相异步电动机具有结构简单、牢固耐用、启动容易、维护方便以及价格低廉等一系列优点,所以在工农业生产和生活各方面都得到了广泛应用。为了保证三相异步电动机的安全运行,电气工作人员必须熟练掌握有关三相异步电动机的安全运行的基本要领,了解对三相异步电动机的安全评估,做到尽可能地及时发现和消除电动机的事故隐患,保证安全生产。 相似文献
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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。 相似文献
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以三相交流电动机为对象,分析研究了可变机械负载、恒定满载电动机的效率特性,并进行了实例分析。对三相交流电动机的设计及选型有一定参考价值。 相似文献
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1 可能引起电动机振动的因素分析电动机本身原因:(1)大型高速电动机结构强度不够。例如固定定子铁芯的纵、横拉筋数不足,或者拉筋太单薄,都会引起电动机的强烈振动,甚至将地脚螺栓屡次振断,以致无法继续运行。(2)定子铁芯安装不紧引起振动。(3)电动机的转子不平衡,引起电动机振动。(4)电动机的轴弯曲、轴颈成椭圆,引起电动机振动。(5)鼠笼铜条有较多的断裂或开焊,引起电动机振动。(6)轴承磨损,轴承的间隙超过允许值,电动机产生振动,严重者使定子与转子相磨(扫膛)。(7)电动机的地脚破裂,地脚螺丝或端盖… 相似文献
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贾淳 《工程设计与研究(长沙)》1998,(3):39-42
阐述笼型感应电动机全压起动的优点及条件,讨论了影响电动机起动的因素。对几种降压起动方式进行了分析比较,以便合理选择。对绕线转子电动机的起动方式及应用范围进行了说明。 相似文献
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本文论述了变频调速时交流电动机的运行范围,调速上限,控制方法,最大力矩范围,以及变频调速时对电动机的结构要求。 相似文献
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为研究纯电动汽车车载电源性能,提出并搭建了由异步电动机和直流电动机组成的在环测试平台.异步电动机用来模拟纯电动汽车的牵引电动机,直流电动机用来模拟汽车行驶时的阻力和惯量,对异步电动机和直流电动机分别实施转速控制和转矩控制.分析了电动汽车行驶工况,给出了简单循环工况下参考转速、转距和功率.设计了异步电动机调速系统转速控制器和电流控制器,建立了异步电动机调速系统的数学模型,提出了基于自适应模糊神经网络控制的异步电动机调速系统.仿真和实验结果表明,基于自适应模糊神经网络控制的调速系统明显优于PID控制的交流调速系统,在环测试平台能够较好跟踪参考转速和参考转距的变化. 相似文献
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Sullivan Edith V.; Fama Rosemary; Shear Paula K.; Cahn-Weiner Deborah A.; Stein Maria; Zipursky Robert B.; Pfefferbaum Adolf 《Canadian Metallurgical Quarterly》2001,15(3):342
Motor abnormalities occur in schizophrenia (SZ) and may arise from striatal dysfunction. This study examined whether the pattern of performance on simple and complex motor abilities in SZ was similar to that of patients with Parkinson's disease (PD). Quantitative tests of speeded movement and motor and cognitive sequencing were used to assess 25 SZ, 16 PD, and 84 normal controls (NCs). Sequencing performance was also examined with motor rigidity taken into account. Compared with the NC group, the SZ and PD groups were impaired on measures of motor rigidity and motor sequencing. With rigidity accounted for, the SZ group was significantly more impaired than the PD group on motor sequencing; cognitive and motor processes contributed to the motor deficit. Cognitive sequencing performance predicted motor sequencing performance in PD but not SZ. Although both SZ and PD resulted in significant motor and cognitive sequencing deficits, the pattern and correlates of these deficits differ, suggesting that the affected neural systems underlying motor deficits in SZ are different from those involved in PD. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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文章介绍了一种由传感器和PLC组成的新型电子热继电器保护装置在桥式起重机中的应用。该保护装置对桥式起重机的三相异步电动机起到保护作用,具有过流、过热、断相等保护功能。性能可靠、稳定,可有效地对异步电动机进行保护,大大减少电动机在使用中的故障。 相似文献
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中板高压除鳞系统高压除鳞泵电机转子发生轴向窜动,造成电机滑动,轴承乌金面磨损严重,致使电机振动增大,温度升高。本文根据高压电机的设计与安装,从电机磁力中心线的位置调整,电机转子扬度以及轴承定位游隙等问题入手,全面阐述并从根本上解决了中板高压除鳞泵电机滑动轴承乌金面磨损及电机异常振动、异响、温升的问题,避免了电机因滑动轴承损坏导致电机扫膛烧坏的可能后果。 相似文献
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S Kawaguchi H Noguchi T Sakaki T Morimoto T Hoshida T Yonezawa T Imai H Ohishi 《Canadian Metallurgical Quarterly》1997,41(5):1065-71; discussion 1071-2
OBJECTIVE: We evaluated and analyzed the effect of superficial temporal artery to middle cerebral artery bypass for internal carotid artery occlusion on pure motor function using motor activation single photon emission computed tomography. METHODS: Motor activation single photon emission computed tomographic (SPECT) images were obtained for nine patients who had undergone superficial temporal artery to middle cerebral artery anastomosis for symptomatic internal carotid artery occlusion. All motor activation SPECT images using the finger opposition task on the affected side were obtained before bypass surgery and at 1 week, 1 month, and 3 months after bypass surgery. The results of motor activation single photon emission computed tomography were expressed as negative or positive. RESULTS: Before bypass surgery, the resting SPECT images revealed reduction of cerebral blood flow (CBF) on the affected side in all nine patients. The results of motor activation single photon emission computed tomography in three patients were positive. One week after bypass surgery, the results of the resting and motor activation CBF studies did not demonstrate any marked changes. One month after bypass surgery, the resting CBF increased in four patients. The results obtained for two of the patients revealed preoperative positive motor activation. The results of motor activation single photon emission computed tomography obtained for five patients were positive. Three months after bypass surgery, eight patients experienced improvement in the resting CBF, and the results of motor activation single photon emission computed tomography obtained for seven patients were positive. Among these, the results of preoperative motor activation single photon emission tomography obtained for four patients were negative. CONCLUSION: Superficial temporal artery to middle cerebral artery bypass is useful not only for resting CBF but also for pure motor function based on motor activation SPECT images. From the preoperative motor activation study, it was concluded that patients with preoperative positive motor activation could attain the effect of bypass earlier than patients with preoperative negative motor activation. 相似文献
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Neuropsychological aspects of multiple sclerosis 总被引:3,自引:0,他引:3
Twenty-six persons (five males and 21 females) with the neurological diagnosis of multiple sclerosis, and an equal number of control subjects matched on age, sex, and education were given a battery of tests designed to assess motor and intellectual functioning. Subjects in the multiple sclerosis group displayed marked deficits on all tests of motor skill except grip strength. Although verbal intelligence was not impaired in subjects with multiple sclerosis, these subjects performed more poorly than control subjects on two different tests of memory even though these tasks required minimal motor responsivity. Correlational analyses on the several motor and cognitive tasks revealed that correlations between motor and memory performance were consistently higher in persons with multiple sclerosis than in controls. These results suggest that whereas multiple sclerosis may not have mch effect on the utilization of stored verbal information, the processing and storage of new verbal material are disrupted by the disease to a degree that is paralleled by the extent of motor impairment. This finding is consistent with the view that the memory impairments observed are secondary to the primary motor deficit, but the alternative explanation that memory functions, like motor functions, are especially vulnerable to the demylination process of multiple sclerosis is equally viable at present. 相似文献
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介绍了防爆电机的分类、基本原理及其发展概况,重点分析了国内矿用防爆电机生产的技术现状,并对矿用防爆电机的发展趋势作了展望与预测。 相似文献
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L Rondi-Reig N Delhaye-Bouchaud J Mariani J Caston 《Canadian Metallurgical Quarterly》1997,77(4):955-963
The inferior olivary complex of adult rats was chemically destroyed using intraperitoneal injection of 3-acetylpyridine. Animals were submitted to different motor tasks: hanging test, equilibrium test and motor co-ordination test. The different scores show that 3-acetylpyridine-treated rats had motor co-ordination and static equilibrium deficiencies, whereas their rod suspension capabilities were intact. Animals were also trained on an unrotated rod or on a rod rotating at 5, 10 or 20 r.p.m. 3-Acetylpyridine-treated rats were able to maintain their equilibrium on the unrotated rod and at 5 r.p.m. Moreover, after motor training at 5 r.p.m., rats were able to improve their motor skills and reached the same score as controls. Despite their good motor skills, animals were unable to maintain their equilibrium when rotated at 10 and 20 r.p.m. These results suggest that the inferior olivary complex is needed for motor learning involving the temporal organization of movement. 相似文献