大型直流电机电枢绝缘系统新技术(摘要)

本文通过与瑞士BBC公司合作生产中型F级GN400、350kW电机、大型F级GY900h、2600kW电机和与西德西门子合作生产大型F级轧钢电机,在引进、分析、消化国外先进技术基础上,结合我国目前绝缘制造技术绝缘材料状况,介绍了研制大型直流电机新绝缘—即主绝缘全部粉云母结构、真空压力整浸SD1118通用F级无溶剂漆或6895无溶剂漆的绝缘系     

国内几种大型电机定子线圈F级主绝缘可靠性评定情况

自60年代中期我国开始采用B级合成树脂作为大型电机定子线圈主绝缘的胶粘剂,大大提高了绝缘的性能和电机绝缘的使用寿命及运行的可靠性。这期间B级绝缘的性能经过不断的改进有了大幅度的提高。随着单机容量的迅速增大,运行应力不断提高,对电机绝缘各种性能的要求日趋苛刻。就绝缘的耐温等级而言,虽然由于采用水冷技术限制了绝缘的温升,但是为了提高电机绝缘的使用寿命和运行的可靠性,各先进国家在大型电机上均已采用F级主绝缘材料。我国电工绝缘行业近年来也开发     

133C半无机硅钢片漆的研制与应用

前言 随着电机单机容量的不断提高,对大型电机定子铁芯的绝缘要求越来越高。国外大型电机定子铁芯均采用无机或半无机绝缘,如美国西屋公司、德国西门子公司、加拿大GE公司、瑞士BBC公司、法国A—A公司、日本日立公司等无一例外。而国内硅钢片     

VPI绝缘现状及对策

一、前言 真空压力浸渍(简称VPI)绝缘是当今世界上最好的绝缘处理技术。国外早在50年代已广泛应用,70年代应用于电机的定子整浸绝缘。随着我国加入WTO,国内VPI绝缘技术也热门起来,大多数电机制造公司都要与国际接轨而应用少     

我国绝缘材料发展战略探讨

绝缘材制与绝缘技术是一门边缘科学，绝缘材料生产厂家有专业的也有跨行业的企业。绝缘材料以不同结构形成，在电工设备中发挥不同作用，如绝缘、储能、支撑和保护等作用。因此，绝缘材料是保证电工设备安全运行和提高电工设备技术水平的不可缺少的关键材料。1发展现状绝缘材料国外大型高压电机绝缘全部采用F级环氧粉云母绝缘，有“多胶”和“少胶”两种绝缘体系，均已用于百万千瓦级大型发电机组，电压等级最高达27kV。大电机主绝缘的发展趋势是提高主绝缘的云母含量、热恋电气物理性能、绝缘的工艺水平和大电机的技术经济指标。我国大电…     

大型电机绝缘技术的国内外对比分析

以前国内还不能生产大型的燃气轮发电机组。从美国引进的机组,绝缘技术又绝不转让,定子线圈元件必须高价进口。通过自主创新,发挥自身优势,采用研究开发的“多胶一模压”绝缘工艺研制的定子线圈元件,不仅实现了国产化,取代了进口,同时还使我国大型电机绝缘系统在性能和质量等方面都达到了美国GE公司和瑞士ABB公司的先进水平。     

高压旋转电机线圈的绝缘检测和寿命预测

1、序言近年来,由于树脂的改进,大型电机的高压定子线圈绝缘在性能方面有了很大的提高。图1表示大型电机绝缘生产量的变化。二十年前由于热固性树脂绝缘的研制成功,沥青绝缘就停止了生产,并几乎全部更换为树脂绝缘。又经过二十年由于环氧绝缘问世,聚脂绝缘已     

环氧树脂成为助推电机主绝缘市场发展的新引擎

正众所周知,电机的寿命也主要取决于绝缘的寿命,因此把绝缘称作电机的心脏。在电机中有许多种绝缘材料,最重要的是大型高压电机定子绕组导体的对地绝缘,又称主绝缘。主绝缘在电机绝缘系统中起着决定性作用。至今世界各大电机公司仍在不断改进各自的绝缘系统,相关科技人员一直在竞相研制或改进新的主绝缘材料,以提高主绝缘性能,使电机具有更大市场竞争力。主绝缘被认为是可持续发展的课题,而主绝缘材料中改进的主要内容和     

大型高压电机主绝缘改性工作简况报导

1971年4月份在桂林召开了大型高压电机绝缘座谈会。会议以战无不胜的毛泽东思想为指针,认真地总结、交流了环氧粉云母绝缘在大型高压电机上应用的经验和教训,讨论了粉云母绝缘的发展方向,并提出了改进环氧粉云母绝缘的措施和意见。环氧粉云母绝缘从65年起逐步应用于大中型高压电机定子绝缘以来,到71年初已生产出     

大型电动机的绝缘诊断技术

近几年来,随着设计和制造技术的迅速发展,要求电动机绝缘在比过去更加严酷的条件下具有较高的可靠性。最近,由于传感器、仪器类的开发和系统工程技术的进步,在电机绝缘的诊断技术方面,也强烈要求向自动化、联机化方面发展。为了开发大型电机绝缘诊断技术,制造厂和用户形成一体进行合作推进了这一工作。本文就大型直流电动机和     

无稀释剂漆浸渍云母型大电机绝缘体系的发展

本文阐述了无稀释剂漆浸渍型大电机绝缘体系在世界上的发展状况。介绍了该绝缘体系的构成以及通过与国外合作生产,在电机产品上听取得的技术成果。通过试验与生产实践,摸索出该体系中浸渍漆的维护方法,并对该绝缘体系的国产化进行了探讨。指出了今后大型高压电机绝缘的发展方向。     

Electrical breakdown in high-voltage winding insulations of different manufacturing qualities

Due to an increasing demand for new, or the refurbishment of power stations, high-voltage rotating machines continue to play a significant role in generating electrical energy. An important component of these machines is their electrical insulation. Although much research has been done to improve the material, about a quarter of all failures still are related to insulation problems. Research to improve winding insulation is very complex because a large number of factors influence insulation life, among them the raw materials, size of the mica tapes, geometrical characteristics of the bar and taping- or manufacturing techniques. The results show that electrical tree propagation is the main electrical degradation mechanism that leads to breakdown of the main wall insulation and that poor impregnation of the insulation and type of taping can reduce time to breakdown significantly.     

The improvement of the electrical insulation of high voltage electrical machines

Comparative parameters are presented for the electrical insulation systems of high voltage electric machines. Composite insulation materials produced by different manufacturers are studied. The influence of the structure and composition of electrical insulation materials on the main operation parameters (electric strength, dielectric losses, the mechanical characteristics, and resistance to thermal cycling) of the insulation systems of electric machines is shown.     

Effect of surge voltage risetime on the insulation of low-voltagemachines fed by PWM converters

This paper investigates the repetitive surge-voltage withstand of low-voltage mush-wound machines operated on adjustable-speed drives (ASDs) using insulated gate bipolar transistor (IGBT) semiconductor technology. Historical work on surge testing of motor insulation has focused on one or more of the following aspects: (1) large horsepower motors; (2) medium-voltage form-wound motors; (3) single-shot impulse-type transients; or (4) low-voltage machines with surge risetimes >200 ns. IGBT drives can have risetimes of 50-200 ns. Thus, a new study on electrical stress of insulation systems due to the nonlinear voltage distribution of mush-wound motors when subjected to repetitive steep dV/dt square-pulse waveforms (rather than impulse wave testing) is presented. Magnitude and risetime of the repetitive ASD surge-voltage transient induced on the machine terminals is reviewed first. Next, surge propagation into the winding was investigated to identify maximum voltage stress points on the conductor insulation. Potential failure mechanisms observed at these points are then discussed. The significance of decreasing surge risetime and increasing cable lengths on internal nonlinear voltage distribution is studied with experimental results from a 7.5-hp motor with a tapped stator winding     

Understanding surface partial discharges in HV coils and the role of semi-conductive protection

An electrical insulating system in high voltage rotating machines is subjected to several stresses that cause changes of material properties during its lifetime. This phenomenon reduces progressively ability of the insulation to withstand the service stresses. Internal partial discharges can be located inside the high voltage insulation and usually they are dangerous for life-cycle duration. Surface discharges are generated at the solid/air interface in the gaps of machine stator slots or at the slot exits. Surface discharges can cause more intensive deterioration of the insulation, accelerate aging processes and definitively take aim toward premature failure of the machine. The application of conductive or semi-conductive protection layer provides certain protection for solid insulation from these discharges. Semi-conductive corona protection tapes are used on the coils at the slot exit region to electrical field control and prevent surface discharges. Laboratory measurements of the surface partial discharge quantities in specimens of high voltage coils with mica insulation were performed. The aim of the paper is to describe theoretically the development of surface discharges in rotating machines and to present surface partial discharge development in HV motors when semi-conductive layer protection is missing. The results can be found useful to understand better the surface discharge development and importance of high-quality semi-conductive protection technology.     

大型空冷汽轮发电机模压定子线棒绝缘结构研究

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。     

Assessing Test Data

Online partial discharge (PD) testing has been used for more than half a century to provide useful information for diagnosing and monitoring the integrity of stator winding insulation of large generators and motors. Interest in online PD detection and monitoring has as the technology, which was originally used on machines rated higher than 10,000 V, has expanded its application to the smaller, lower-voltage (e.g., 4,160 or 6,900 V) machines. However, questions remain on how to assess stator insulation problems using PD test data. This article documents the most recent developments in research and applicable guides and standards related to online PD monitoring on rotating machines.     

银川东750kV变电站的电容型设备绝缘状态在线监测

为了保证银川东750 kV变电站电气设备安全、稳定运行,采用了先进的信号及测量技术、相位测量基准获取技术,建立了电气设备绝缘状态在线监测系统。实现了对750 kV主变压器套管及主变压器高、中压两侧CVT的在线监测。运行结果表明:在线监测系统各项指标达到了对电容型设备绝缘状态进行实时监测的技术要求。     

Measures and technologies to enhance the insulation condition monitoring of large electrical machines

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.     

An acoustic diagnostic technique for use with electric machineinsulation

Many of the electrical failures of large electric machines have mechanical precursors. This premise has led to the attempts described here to detect mechanical changes, such as groundwall delamination, by acoustic methods as a means of early detection of incipient failure. By optimally launching an ultrasonic wave into a stator bar and using the conductor as a waveguide, it has been shown possible to interrogate the groundwall insulation and the critical interface region adjacent to the conductor. Laboratory studies using an epoxy mica stator bar subjected to thermal cycling have demonstrated that the acoustic signatures obtained with this method are mirrored by conventional corona spectroscopy conducted simultaneously, although earlier damage is clearly discernible. Based on the results of this study, the acoustic technique appears to have substantial promise as an advanced detection tool