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1、专业好文档600MW发电机碳刷振损问题分析及处理杨俊锋（广东红海湾发电有限公司，广东汕尾 516623）摘 要: 针对广东红海湾发电有限公司2号发电机碳刷振损的问题，分析其原因为集电环磨损严重所致，从而提出车削集电环消除振损的方法，为同类机组作为参考。关键词：发电机，集电环，车削； Analysis on the Damage Causes and Countermeasure for Carbon Brush of 600MW GeneratorYang Junfeng(Guangdong Red Bay Generation Co., Ltd. Shanwei Guangdong 5166
2、23)Abstract: Base on Brush vibration damage For the unit 2 of Guangdong Red Bay Power Generation Co., Ltd., analysis of the reasons for collector ring damage are maded , and turning collecting ring to eliminate vibration is recommended. which may server as a reference for the same unit.Key words: ge
3、nerator; collector ring; turning0 引言2008年9月20日，广东红海湾发电有限公司2号发电机首次出现集电环负极外侧碳刷弹簧断裂，进入10月共出现了10多次的弹簧振断，其中一位置连续出现4次损坏。为了避免严重事故的发生，电厂停机对出现问题的集电环进行了车削处理。滑环原始直径测量值为343mm，车削工作结束后测量滑环直径在340.43mm340.47mm，车削深度为1.28mm。本文就碳刷振损进行研究，推断出集电环表面磨损严重，从而车削集电环，彻底解决碳刷振损问题，避免事故的发生。1 碳刷和集电环概述广东红海湾发电有限公司2发电机为东方电机厂生产的QSFN-600
4、-2-22A型、汽轮机直接拖动的隐极式，二极同步发电机。集电环是合金钢锻件,材料牌号为T10A，表面有等距离的螺旋槽，集电环周向均布30 个轴向斜孔, 发电机集电环的宽度为304.8mm ,圆周方向布置了8 排碳刷, 碳刷采用天然石墨材料粘结制成，有较低的磨擦系数和一定的自润滑作用。每个电刷带有两根柔性的铜引线(即刷辫)。螺旋式弹簧恒定地将压力施加在电刷中心上。宽度方向每排布置有2 个刷盒, 刷盒 采用了盒式刷握结构，每个刷盒能装4块碳刷,共计8 个碳刷。发电机采用上海摩根碳制品有限公司的NCC634 碳刷,尺寸为25.438.1102mm，总的摩擦面积(一个集电环)为:25.438.164=
5、61935.36mm2。碳刷布置图见图1。图1碳刷布置图2 碳刷振损2号机组与2008年2月通过168h试运。2008年6月小修完成后，负极集电环碳刷出现振动大的现象。9月20日，D列出现弹簧断裂。10月份全月D列共出现了12次弹簧断裂情况，出现振损问题的碳刷主要出现在D列碳刷（负极集电环外侧）的2个碳刷上，而且外侧比里侧的振动程度更严重。正极的A列、B列以及负极的C列的碳刷无振动，手触摸碳刷辫子，几乎感觉不到振动，而D列振动特别明显，尤其最外侧的2组碳刷，可以看到碳刷辫在明显的上下抖动，弹簧振颤十分明显。观察振损的碳刷，发现碳刷与集电环接触面有异常波纹状的沟槽，碳刷崩角情况严重。由于碳刷在刷
6、盒内上下振动，碳刷与刷盒接触边缘部分也出现了明显的磨损痕迹，从痕迹判断，碳刷上下移动的幅度有1mm。破损的碳刷与正常碳刷比较见图2。图2 破损的碳刷与正常碳刷的比较由于A、B列碳刷无振动，把正极研磨好的碳刷换到D列，振动情况没有改善。把1号发电机相同位置的碳刷（1号发电机与2号发电机同类型）互换，互换后振动情况也没有改善。D列碳刷的电流分布也有较大差别，具体见表1表1 机组430MW时D列碳刷电流分布每个刷握四根碳刷电流（A）D1刷握98.3/86.2/79.4/60.4D2刷握23.3/53.3/90.3/45.3D3刷握99.8/57.2/56.3/75.3D4刷握21.5/66.4/70
7、.6/68.3D5刷握116.1/61.9/97.7/76.2D6刷握76.9/63.3/72.8/47.2D7刷握79.2/48.3/67.5/42.4D8刷握36.4/49.9/66.0/54.7另外，从集控室的转子振动值来看，转子的各项振动值正常。3 碳刷振损原因分析从上述现象分析，可以判断碳刷盒内的弹簧片断裂是由于与之相对应的碳刷在频繁地抖动，造成该弹簧片随之大幅度地频繁伸缩，最终造成金属疲劳而发生断裂。造成碳刷在刷盒内高频振动的原因有：气垫与吸附、刷架装偏、集电环表面磨损。气垫与吸附：对于集电环表面螺栓槽，在很大程度上解决了此问题。另外通过正、负极碳刷对调，以及1号发电机与2号发电机
8、相同位置电刷对调，都不能解决振动来看，气垫引起振动不能成立。刷架装偏的可能：对于小修后出现这样的问题是存在这种可能性的。实际测量刷架与转子轴的同心度，基本无偏差。另外对于东方电机这种整体刷架结构的方式，在安装上只要求整刷盒底部到集电环外径距离（约24mm）的距离。所以刷架对此影响也可排除。集电环表面磨损严重：从振损的碳刷与集电环接触面的不平滑的波纹，可以基本确定。试想一下，如果集电环表面非常光滑，与之相接触的碳刷表面怎么可能出现起伏状的纹路？在与集电环表面接触磨合的过程中，碳刷表面逐渐形成了与集电环表面相吻合的纹路。碳刷表面的破损，是由于发生了异常振动的碳刷，不断地冲击着集电环的表面，在持续的
9、冲击力的作用下，逐渐使碳刷表面或四周发生破裂。集电环磨损在随后的停机中得到证实。其中集电环第2、第3环出现了W形沟槽。集电环短时间严重磨损分析：a.使用了不同牌号的碳棒。这点可以排除，因为使用的均为上海摩根碳制品有限公司的NCC634 碳刷。1号机组无异常。b.有硬物划伤集电环，小修后对集电环进行了检查，表面无划痕。另一种可能时刷握底部距集电环太低，转子跳动时，刷握底部金属摩擦了集电环。通过D列刷盒底部检查，这种情况也排除。c.可能是加工生产集电环时，生产设备方面出现了系统偏差。也有可能是装配时，同心度不好，工艺控制不到位等，造成最外侧部位超差。这样造成在运行中，碳刷与集电环接触发生异常磨擦，
10、造成集电环表面的过度磨损。从表2中可以看出集电环硬度有一定的差异。d.其它方面的原因：如碳刷研磨不好，弹簧压力过大等等，不可排除。表2 集电环车削前后硬度数据部件名称发电机滑环仪器型号HT-2000A硬度仪1、车削前硬度：编号硬度值编号硬度值编号硬度值编号硬度值1HB2914HB3247HB32110HB3332HB3155HB3278HB3223HB3236HB3229HB3332、车削后第1点硬度：编号硬度值编号硬度值编号硬度值编号硬度值1HB3264HB3247HB36610HB3662HB3245HB3418HB3673HB3376HB3629HB3673、车削后第2点（与第一点相距9
11、0度）硬度：编号硬度值编号硬度值编号硬度值编号硬度值1HB3524HB3667HB40210HB4182HB3665HB3378HB4133HB3626HB4169HB418车削前硬度范围是HB297-HB333,车削后硬度范围是HB324-HB418.。注：表中编号为“1”的点是指负极第1环，编号为“10”的是指负极第10环的点。4 危害分析及防范措施碳刷振损首先是增加了发电的成本，一根弹簧断裂后，整个刷握报废，一个刷握的费用超过万元。弹簧断裂后，断裂的金属残片落入冷却风道、或碳刷与集电环的间隙间，引起短路或集电环表面划伤。振损情况由集电环表面不光滑引起，随着时间的推移，磨损情况会加速发展，
12、这也是碳刷振损情况后来频繁发生的原因。碳棒崩角、破损，导致电刷与集电环接触不良，从而导致电刷电流分布不均匀。电流不均匀通常会引起局部碳刷过热，多个电厂集电环烧毁就起因于此。集电环划伤严重，需要车削集电环，多次车削后需更换集电环，对氢冷机组，现场更换集电环将增加导电螺钉处密封困难。对现代发电企业，力争发电量作为首要任务，所以对于发生了振损情况，又不能停机处理。增加了运行的风险。所以必须采取有效的防范措施，措施如下：（1）定期或不定期对集电环上的碳刷进行电流分布测量, 并做好记录；若发现碳刷上电流分布不均, 超过每个碳刷允许值,应对碳刷弹簧压力进行调整, 使碳刷上的电流分布平衡；若调整碳刷的弹簧压
13、力还不能满足要求, 应查明原因并进行处理,使之满足要求。（2）定期或不定期用红外测温装置对发电机转子集电环、碳刷温度进行测量,并作好记录；若发现集电环、碳刷上的温度偏高,应通知检修人员进行处理, 并查明原因。5 集电环处理办法由于集电环存在严重的凹凸不平问题，需要对其进行处理。处理的方法一般有两种，其一车磨。车磨可以在盘车状态下进行。对于该机组的盘车速度为1.5转/分钟，车磨方法耗时较长，另外车磨时扬尘较多；另一种方法是车削，车削时需要较高的转速。可以节省时间。所以现场采用车削的方法。车削工艺如下：（1）车床固定：在刷架台板钻2个16的孔，固定住车床。（2）确定刀架行走导轨与转子集电环轴向平行
14、度控制在0.02mm/m以内，防止集电环产生锥形。测量时需停盘车，因为整个机组在热态下，停盘车时间要严格控制，调节级温度在350左右时，停盘车的时间控制在25分钟。（3）机组冲转，采用高压缸冲转方式，将转子的速度控制在6080转/分钟。由于低转速取决于热工的自动控制系统调节能力。实际车削时的转子转速在73r/min左右，转速3r/min的波动。首先对集电环进行粗车，时间为4个小时。由于车刀径向走动为人工控制，所以刀走一遍的时间不固定。粗车至最深沟槽部分消失（最深部位在从外数第2环位置）后，粗车完成。粗车完成后进行最后一刀精车，精车完成后进行打磨。（4）打磨时转子转速可以适当提高，打磨时实际转速
15、控制在150r/min。集电环表面螺旋沟先用锉刀倒角，然后用锉刀裹砂纸磨光，直至光滑、无棱角。（5）发电机转速控制在150r/min（实际可以更高些，也不可太高，转速太高对打磨工具及人员存在较大风险），先用200400号砂纸进行细抛光，最后用金相砂纸进行精抛光，使其粗糙度达到0.02，满足运行要求。（6）车削、打磨后的集电环应重新测量偏心度、光洁度及集电环直径，若不满足要求应在进行车削、打磨，直至合格为止。6 结论（1）碳刷振损应立即展开原因分析，若可确定为集电环表面不平滑，应立即停机处理。（2）集电环出厂试验报告应用硬度测量数据。（3）对600MW发电机组，采用高压缸冲转控制转速，现场车削方
16、法得当，可以节省时间。参考文献1卢加林.纳雍发电总厂2号发电机转子集电环烧毁事故分析及处理J. 广西电力,2006 (1)：36-382 国龙,田井武. 300MW发电机转子集电环烧损原因及处理 J. 吉林电力技术,2000 (1)：11-143 李公净，方宪人.300MW机组电刷烧毁故障分析及处理J.山西电力技术,1995（6）：24-274 彭远崇. 发电机励磁碳刷事故分析及对策. J.电力安全技术，2003（7）：27-285 何曙光.发电机转子集电环及电刷烧损原因分析与预防J.湖南电力,2004（4）：41-43作者简介：杨俊锋（1975），男，河南南阳人，1999年华北电力大学（北京
17、）热动专业毕业，2005年华南理工大学电力系统及其自动化专业毕业，工学硕士，电气工程师，现从事发电厂电气一次点检工作。电话：13828985158Editors note: Judson Jones is a meteorologist, journalist and photographer. He has freelanced with CNN for four years, covering severe weather from tornadoes to typhoons. Follow him on Twitter: jnjonesjr (CNN) - I will always w
18、onder what it was like to huddle around a shortwave radio and through the crackling static from space hear the faint beeps of the worlds first satellite - Sputnik. I also missed watching Neil Armstrong step foot on the moon and the first space shuttle take off for the stars. Those events were way be
19、fore my time.As a kid, I was fascinated with what goes on in the sky, and when NASA pulled the plug on the shuttle program I was heartbroken. Yet the privatized space race has renewed my childhood dreams to reach for the stars.As a meteorologist, Ive still seen many important weather and space event
20、s, but right now, if you were sitting next to me, youd hear my foot tapping rapidly under my desk. Im anxious for the next one: a space capsule hanging from a crane in the New Mexico desert.Its like the set for a George Lucas movie floating to the edge of space.You and I will have the chance to watc
21、h a man take a leap into an unimaginable free fall from the edge of space - live.The (lack of) air up there Watch man jump from 96,000 feet Tuesday, I sat at work glued to the live stream of the Red Bull Stratos Mission. I watched the balloons positioned at different altitudes in the sky to test the
22、 winds, knowing that if they would just line up in a vertical straight line we would be go for launch.I feel this mission was created for me because I am also a journalist and a photographer, but above all I live for taking a leap of faith - the feeling of pushing the envelope into uncharted territo
23、ry.The guy who is going to do this, Felix Baumgartner, must have that same feeling, at a level I will never reach. However, it did not stop me from feeling his pain when a gust of swirling wind kicked up and twisted the partially filled balloon that would take him to the upper end of our atmosphere.
24、 As soon as the 40-acre balloon, with skin no thicker than a dry cleaning bag, scraped the ground I knew it was over.How claustrophobia almost grounded supersonic skydiverWith each twist, you could see the wrinkles of disappointment on the face of the current record holder and capcom (capsule commun
25、ications), Col. Joe Kittinger. He hung his head low in mission control as he told Baumgartner the disappointing news: Mission aborted.The supersonic descent could happen as early as Sunday.The weather plays an important role in this mission. Starting at the ground, conditions have to be very calm -
26、winds less than 2 mph, with no precipitation or humidity and limited cloud cover. The balloon, with capsule attached, will move through the lower level of the atmosphere (the troposphere) where our day-to-day weather lives. It will climb higher than the tip of Mount Everest (5.5 miles/8.85 kilometer
27、s), drifting even higher than the cruising altitude of commercial airliners (5.6 miles/9.17 kilometers) and into the stratosphere. As he crosses the boundary layer (called the tropopause), he can expect a lot of turbulence.The balloon will slowly drift to the edge of space at 120,000 feet (22.7 mile
28、s/36.53 kilometers). Here, Fearless Felix will unclip. He will roll back the door.Then, I would assume, he will slowly step out onto something resembling an Olympic diving platform.Below, the Earth becomes the concrete bottom of a swimming pool that he wants to land on, but not too hard. Still, hell
29、 be traveling fast, so despite the distance, it will not be like diving into the deep end of a pool. It will be like he is diving into the shallow end.Skydiver preps for the big jumpWhen he jumps, he is expected to reach the speed of sound - 690 mph (1,110 kph) - in less than 40 seconds. Like hittin
30、g the top of the water, he will begin to slow as he approaches the more dense air closer to Earth. But this will not be enough to stop him completely.If he goes too fast or spins out of control, he has a stabilization parachute that can be deployed to slow him down. His team hopes its not needed. In
31、stead, he plans to deploy his 270-square-foot (25-square-meter) main chute at an altitude of around 5,000 feet (1,524 meters).In order to deploy this chute successfully, he will have to slow to 172 mph (277 kph). He will have a reserve parachute that will open automatically if he loses consciousness
32、 at mach speeds.Even if everything goes as planned, it wont. Baumgartner still will free fall at a speed that would cause you and me to pass out, and no parachute is guaranteed to work higher than 25,000 feet (7,620 meters).It might not be the moon, but Kittinger free fell from 102,800 feet in 1960 - at the dawn of an infamous space race that captured the hearts of many. Baumgartner will attempt to break that record, a feat that boggles the mind. This is one of those monumental moments I will always remember, because there is no way Id miss this.