电力专业英语第九讲

1、山东交通学院电气系张建军 词汇AC = alternating-current 交流电rotate v. 旋转convert v. 使转变； 兑换，换算; 侵占DC = direct-current 直流电turbine n. 涡轮机；气轮机；水轮机coil kl n. 线圈； 卷，（一）盘; 盘卷之物; 纷乱，纠缠不清;pole n. 磁极；电极 杆; 物 极点，顶点; vt.用篙撑船，摆船brush n. 电刷；刷子，画笔; 灌木丛; 小冲突insulate nsjuletv. 使绝缘；使隔离，使孤立; 使隔热;energizeendaz v. 给予.电压；励磁；加强，给与以活力; 使活跃

2、; 物 给与能量efficient fnt a. 有效力的；能干的；收效大的excitation eksaten n. 励磁；激发（过程）; 激动;couple v. 连接 n. 对，双; 配偶，夫妻;kilowatt n. 千瓦positivepztv a. （电）阳；正的；积极的; 确实的，肯定的; negative negtv a. （电）负的，阴的；反抗性的; 无预期结果的;消极性magnet mgnt n. 磁石，磁铁 ；有吸引力的人或物; 物 磁体magnetomgni:t n. 磁电机，永磁发电机in the case of 就.来说；至于.课文内容GeneratorsAC Ge

3、neratorsAn alternating-current generator is a rotating machine for converting mechanical energy into alternating-current electric power. As in the case of a dc generator, the rotating part of the machine is driven by a source of rotating power external to the machine itself. An alternating-current g

4、enerator交流发电机dc generator直流发电机;Alternating-current generators, also called “alternators”, can be divided into three types according to the type of drive or prime mover. There are direct-connected engine-driven (steam or internal combustion) ac generators, water-wheel ac generators, turbine-driven ac

5、 generators.alternator:ltnet(r)交流发电机;according to the type of drive or prime mover根据原动机驱动类型不同steam or internal combustion蒸汽机或内燃机water-wheel ac generators水轮发电机turbine-driven ac generators涡轮驱动交流发电机Operation Basically, the alternator operates on the principle of generator action-voltage is set up in co

6、ils of wire when they are moved in a magnetic field in such a way as to cut the magnetic lines of force. operates on the principle of generator基于发电机的工作原理运行action-voltage 动作电压，工作电压，感应电压coils of wire绕组线圈when they are moved in a magnetic field in such a way as to cut the magnetic lines of force当他们在磁场中以

7、切割磁力线的方式移动时This is the same principle on which the dc generator operates. But there is a basic difference between dc generators and alternators in accomplishing the relative motion between coils and field.in accomplishing the relative motion between coils and field在磁场和绕组线圈间实现相对运动In a dc generator, t

8、he magnetic field is set up by placing electro-magnetic field poles around the inside of the housing or stator. Coils are placed on the rotor so that when the rotor rotates, the coils are cutting across the magnetic lines of force set up by the poles and voltage is produced in the rotor coils. by pl

9、acing electro-magnetic field poles around the inside of the housing or stator通过把电磁场的磁极放在外壳或定子内部the coils are cutting across the magnetic lines of force set up by the poles and voltage is produced in the rotor coils线圈切割由定子中磁极所产生的磁力线，随之在转子中产生出电压By the use of a commutator and brushes, voltage is taken

10、from the rotor.In an ac generator, the electro-magnetic fieldthe source of the magnetic lines of forceis generally placed on the rotor and the coils in which the voltage is to be generated are mounted around the inside of the stator. By the use of a commutator and brushes通过使用换向器和电刷the electro-magnet

11、ic fieldthe source of the magnetic lines of force电磁场-磁力线的来源and the coils in which the voltage is to be generated are mounted around the inside of the stator. 用来产生电压的线圈被安装在定子内部In this case, the rotating field sweeps the lines of magnetic force across the stationary coils and produces the voltage in t

12、hem.In this case在这种情况下; 既然如此; 这样的话;the rotating field sweeps the lines of magnetic force across the stationary coils旋转的磁场使得磁力线扫过静止的线圈and produces the voltage in them并且在线圈中产生电压Alternators with stationary coils (or stationary armature, as it is sometimes described) have distinct advantages over altern

13、ators with rotating coils and are the most common type. stationary coils 静止的（固定的）绕组线圈静止的（固定的）绕组线圈 stationary armature静止的电枢静止的电枢have distinct advantages over alternators with rotating coils 对于对于那些旋转的绕组那些旋转的绕组线圈而言，有明线圈而言，有明显的优势显的优势and are the most common type并且是最常见的类并且是最常见的类型型 If the generator coils a

14、re placed on the rotor, two or more slip rings must be used for conducting the ac power to the external circuit which the generator feeds. Such rings are a frequent source of trouble, particularly at the high voltage put out by standard alternators. two or more slip rings must be used必须要使用 两个或更多的滑环f

15、or conducting the ac power to the external circuit which the generator feeds用来把交流电能引导到发电机所供电的外部电路Such rings are a frequent source of trouble这一类的滑环是频繁出现的故障源particularly at the high voltage put out by standard alternators. 特别是由标准发电机的高压所引起If stationary coils are used, the generated ac power can be take

16、n directly from the coil leads to output bus bars. Also, if the coils are on the rotor, it is more difficult to properly insulate them, and they are subjected to heavy centrifugal forces and vibrations. the generated ac power can be taken directly from the coil leads to output bus bars发出的交流电能可以直接由线圈

17、引导到母线 Also另外it is more difficult to properly insulate them很难使它们可靠绝缘and they are subjected to heavy centrifugal forces and vibrations并且它们还要受到严重的离心力和振动的影响 When the electro-magnetic field is placed on the rotor, as in most commercial alternators, the direct current necessary to energize the field must

18、be conducted to and from the rotor by the use of slip rings. as in most commercial alternators像大多数商用发电机那样the direct current necessary to energize the field must be conducted to and from the rotor by the use of slip rings用于励磁的直流电流必须要由滑环来流经转子However, the voltage seldom exceeds 250 volts and the amount

19、 of power involved is so small as to cause no particular difficulties. WindingsIn general, windings for alternators are the same as for dc generators. Single-phase windings are almost never used in alternators. the voltage seldom exceeds 250 volts 电压很少超过250伏and the amount of power involved is so sma

20、ll as to cause no particular difficulties并且所涉及的电能非常少，因此不会带来问题 Single-phase windings are almost never used in alternators在交流发电机中几乎从来不用单相绕组Generators for single-phase railroad supply are the exceptions. Usually, alternator windings are arranged to provide three-phase output of ac electric power, such

21、an arrangement is most efficient and economical. Single-phase power can be taken from a three-phase alternator. Generators for single-phase railroad supply are the exceptions用于单相轨道供电的发电机属于例外such an arrangement is most efficient and economical这样的安排是最有效和经济的Actually, three-phase windings in alternators

22、 are simply three single-phase windings properly spaced in the stator slots. three-phase windings in alternators 发电机中的三相绕组are simply three single-phase windings properly spaced in the stator slots是三个单相绕组在定子凹槽中适当的放置 Field ExcitationGenerally, current is supplied to the field windings on the rotor by

23、an individual exciter which may be driven directly or through a gear reduction. Excitation voltage varies between 120 and 250 volts. Excitation voltage is also often obtained from exciters coupled directly to the alternator shaft or from a bank of batteries. Field Excitation励磁，场激励;by an individual e

24、xciter由单独的励磁机which may be driven directly or through a gear reduction它可以直接驱动或经过齿轮减速后驱动a bank of batteries蓄电池DC Generators A direct-current generator is a rotating machine for converting mechanical energy into direct-current electric power. A dc generator is driven by mechanical means, such as a stea

25、m engine, diesel engine or electric motor. Direct-current generators are rated in kilowatts, sizes range from a fraction of a watt to several thousand watts.A dc generator is driven by mechanical means直流发电机由机械方式驱动such as a steam engine, diesel engine or electric motor像是蒸汽机，柴油机，电动机are rated in kilowa

26、tts额定功率为千瓦sizes range from a fraction of a watt to several thousand watts型号从几分之一瓦到几千瓦Operation The basic electrical principle underlying operation of dc generators is called “generator action”. If a length of wire is moved through a magnetic field in such a way that the wire cuts between the North a

27、nd South poles producing the magnetic field, an electric voltage will be set up in the wire . principle underlying operation基本操作原理generator action发电机效应If a length of wire is moved through a magnetic field in such a way that the wire cuts between the North and South poles producing the magnetic field

28、如果一定长度的导线在N极和S极之间以切割磁力线的方式移动Of course, the voltage set up in a single length of wire would be small. But if a large number of wires were connected end to end and rotated in the magnetic field, the voltage set up in the series of wire lengths would be equal to the sum of voltages set up in the indivi

29、dual lengths wire. “Generator action” is the effect whereby the voltage is set up in a moving conductor.Of course, the voltage set up in a single length of wire would be small. 当然，在单根一定长度的导线中产生的电压将很小。But if a large number of wires were connected end to end and rotated in the magnetic field但是假如大量的导线首

30、尾相接并且在磁场中旋转in the series of wire lengths 在这一系列的导线长度中whereby借以; 通过; 与一致;Generator action” is the effect whereby the voltage is set up in a moving conductor发电机效应就是通过在移动的导体中建立电压的效应In dc generators, the conductors are wound into coils and mounted in slots on the armature or rotating element within the u

31、nits housing. The ends of each coil of conductors are brought out to one end of the armature where they are connected to individual insulated bars in an assembly of such bars, which is mounted around the armature shaft. In dc generators, the conductors are wound into coils and mounted in slots on th

32、e armature or rotating element within the units housing在直流发电机中，导体被绕成线圈并安装在机壳内的电枢或旋转部分的凹槽中。This assembly is called the “commutator”, which is required to provide direct-current output from the generator. The wires that come out of the generator, one for the positive side of the dc output and one for

33、the negative side, are connected within the generator to carbon brushes which ride on the commutator. The brushes pick up the electric current from the commutator and pass it to the circuit being fed by the generator.The magnetic field required for generator action is produced in three ways: By perm

34、anent magnets, in which case the machine is called a magneto. Magnetos are generally small in size and capacity due to the limited strength of permanent magnets. Magnetos are used for various speed indicating devices.The magnetic field required for generator action is produced in three ways用于发电机效应的磁

35、场可以由三种方式产生Magneto永磁发电机Magnetos are used for various speedindicating devices.永磁磁电机用于各种速度的指示装置By electromagnets excited by a direct-current source independent of the generator itself. In such cases, magnetic pole pieces are parts of the stator (stationary housing of the generator in which the armature ro