共查询到20条相似文献,搜索用时 31 毫秒
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Nelson J.K. Azizi-Ghannad S. 《Dielectrics and Electrical Insulation, IEEE Transactions on》2004,11(1):102-112
The utility of condition monitoring of the stator insulation structure of large machines has been enhanced substantially by the use of computer-based analysis of partial discharge signatures. A number of indices are examined through tests in a multistress aging facility to assess their promise in describing insulation degradation in machine insulation. In transitioning such tests to the field environment, an operational test is also described which offers some promise in identifying degradation without prior baseline data for a machine. On the basis that most electrical failures have mechanical precursors, acoustic methods are described for assessing stator bar mechanical integrity. This includes both using the conductors as waveguides and also employing acoustic emission for the location of large discharges. 相似文献
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大型汽轮发电机定子绕组的脉冲传播模型 总被引:10,自引:4,他引:6
利用多导体输线原理,建立大型汽车轮发电机定子绕组的脉冲传播模型,模型参数是基于似稳电磁场的有限元数值计算方法,根据电容、电感、电导、阻抗、传播速度间的关系求得。文中详细描述了单根线棒、单相绕组及考虑相间耦合的绕组仿真模型。并将仿真计算结果与200WM汽轮发电机实验结果进行了比较,证实了模型的可靠性。 相似文献
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本文根据大型空冷汽轮发电机的结构特点,重点研究了端部成型、导线压制以及主绝缘模压等定子线圈的制造工艺,并就端部成型及模压等一些关键工序所采取的新工艺和新工具与水冷定子线圈进行了对比,进而形成了一套完整的空冷定子线圈制造体系。 相似文献
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研究了多胶模压的大型空冷汽轮发电机定子线棒绝缘体系,包括定子线棒的导线绝缘结构、主绝缘结构、防电晕结构、定子线棒制造工艺。通过性能指标测试确定了所用主绝缘材料、防晕材料,最终对定子线棒进行了性能评定。确定了大型空冷汽轮发电机定子线棒绝缘结构、膜压工艺。真机线棒结果表明:定子绝缘厚度薄、电性能高,绝缘的设计场强超过了3 kV/mm。 相似文献
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大型汽轮发电机定子线棒高频分布参数的测量 总被引:2,自引:4,他引:2
为研究局部放电信号等高频信号在电机定子绕组中的传播特性,需要确定电机定子线棒的高频分布参数。该文提出了基于多导体传输线(MTL)理论的大型电机定子线棒高频分布参数的测量方法。给出了三种不同条件下的大型汽轮发电机定子线棒分布参数的测量结果,分别是:用铝薄纸裹住单根定子线棒的情况;把单根定子线棒放在电机槽里的情况:双根定子线棒放在电机槽里的情况。测试结果较好地解释了陡前沿脉冲信号在电机定子绕组槽部线棒中是以两种速度沿线棒传播的现象。 相似文献
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异步电动机定子绕组匝间短路故障检测新方法 总被引:6,自引:0,他引:6
定子绕组匝间短路是异步电动机常见故障之一,因此研究其检测方法具有重要意义。针对异步电动机定子绕组匝间短路与转子断条故障瞬态进行仿真并分析仿真结果,指出异步电动机转子故障对定子绕组匝间短路故障检测存在不利影响,甚至导致故障误判。提出计及转子故障时的异步电动机定子绕组匝间短路故障检测新方法,该方法关键在于预先采用频谱校正与自适应滤波技术滤除定子电流中由转子故障所导致的特征频率分量。大量仿真与实验结果表明,该方法可以避免将转子故障误判为定子绕组匝间短路故障,使定子绕组匝间短路故障识别可靠性大幅提高。 相似文献
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超声波技术在大电机绝缘检测中的应用研究 总被引:5,自引:2,他引:3
用研制的检测系统 ,对大电机定子线棒进行了绝缘超声波参数测量和绝缘缺陷的检测试验。结果表明 ,使用 0 5MHz、 0 8MHz和 1 2MHz的超声换能器 ,此系统可以测量大电机定子绝缘的超声波参数 ,从而使超声波技术成为一种绝缘老化状态的诊断方法 ;0 8MHz的探头对定子线棒老化早期的绝缘缺陷能得到特征明显的超声A扫描波形 ,为对绝缘介电性能有直接破坏作用的绝缘断裂性裂纹的检测和识别提供了方法 ,对预防因绝缘裂纹导致绝缘击穿、发电机非计划停机具有重要意义。与国际上相同领域内超声波斜入射的透射波法比较 ,本文的超声回波法更具有应用前景 相似文献
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《Electrical Insulation Magazine, IEEE》2004,20(31):25-39
This article presents an overview of some of the significant developments in rotating machine insulation systems that have occurred in the past century. This article describes the chronological development of insulation materials and systems, together with some of the key innovations in manufacturing. For the most part, it was the innovation in materials and manufacturing from wound stator groundwall insulation that paced the development of machine insulation systems. 相似文献
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Yanpeng Hao Guoli Wang Zhidong Jia Hengkun Xie 《Dielectrics and Electrical Insulation, IEEE Transactions on》2005,12(1):104-113
It is a challenge to diagnose insulation condition of stator bars using an ultrasonic technique, due to the complex structures of the stator bars and the high attenuation of the stator insulation. In this paper, five low frequency transducers were used in a pulse-echo configuration to try to test a standby stator bar of a generator (300 MW, 18 kV). With an available transducer, four types of insulation structures were tested on the stator bar. The short side insulation was compared with the large one of the stator bar in the slot. The stator bar near the exit from the slot and the end stator bar, were compared with the stator bar in the slot. The semiconductive coating covered stator insulation was compared with the uncoated one. The stator insulation having an insulation-copper interface was compared with that having an insulation-gas interface. In addition, insulation diagnosis tests in the laboratory were performed on two sets of stator bars, which had been in service for 18 and 23 years, respectively in two generators (300 MW, 18 kV). Field tests were performed on the stator bars near the exit from the slot and the end stator bars of a generator (300 MW, 18 kV). The experimental results demonstrated an availability of low frequency ultrasonic pulse-echo method for insulation condition diagnosis of large generators 相似文献
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大型发电机定子槽楔的松动会引起定子线棒在电磁力作用下剧烈振动,加速主绝缘劣化甚至导致电机运行事故,因而槽楔的松动检测对电机正常运行有重要意义。该文对大型发电机不同固定结构的定子槽楔建立物理模型,研究槽楔松动过程的振动特性,提出通过获取其振动声音和位移特性来综合判断槽楔的松动程度。利用在此基础上开发的一套振动检测系统对实验室定子槽楔松动模型进行了检测,并在电厂进行了现场实测,验证了槽楔物理模型的正确性和检测系统的有效性。 相似文献
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It has been found that stator excitation in brushless DC motor drives can excite mechanical resonances in the motor and, thus, produce acoustic noise in a similar way to switched reluctance drives. A technique has been developed to alter the commutation pattern of a brushless DC motor to avoid exciting and reinforcing these mechanical resonances producing a significant reduction in pure tone acoustic noise which is emitted during mechanical resonance. The origin of the vibration and acoustic noise is explained and the theory of discrete frequency noise reduction described in this paper. The method proposed for quieter control of the brushless DC motor could be achieved at a very low cost 相似文献