電力專業(yè)英語

1、南京工程學(xué)院期末考查報告書成績電氣工程專業(yè)外語b 院（系、部、中心） 電力工程學(xué)院 專 業(yè) 電氣工程及其自動化 班 級 電氣071 學(xué) 生 姓 名 褚楚 學(xué) 號 206070819 任 課 教 師 朱建忠 2010年 7月 南 京 考查要求：1、 對已學(xué)的課程內(nèi)容進(jìn)行總結(jié), 節(jié)選4篇課題作為報告的主題。2、 通過文獻(xiàn)的搜索（可借鑒google、yahoo和電子圖書館的外文期刊），查找數(shù)篇與課程相關(guān)的資料（一定是經(jīng)過選擇后的文獻(xiàn)，要最好的）。3、 通過已經(jīng)掌握的專業(yè)詞匯和課題背景對已查找的文獻(xiàn)進(jìn)行精心分析，分析角度可從詞匯、語法和課題背景等。4、 對文獻(xiàn)進(jìn)行通篇翻譯，翻譯最好可直譯，遇拗口的語句

2、可選擇意譯。5、 翻譯后從文中選出關(guān)鍵字。6、 總結(jié)翻譯成果，寫下中心思想。7、 考查報告總結(jié)（語句需簡潔）。page1. the production of electrical energy(電能生產(chǎn))1.english testfrom reference 1in large steam power plants, the thermal energy stored in steam is converted into work by means of turbines. a turbine consists essentially of a shaft or rotor fixed i

3、n bearings and enclosed in a cylindrical casing. the rotor is made to turn smoothly by means of jets of steam from nozzles around the periphery of the turbine cylinder. these steam jets strike blades attached to the shaft. central power stations employ condensing turbines in which the steam passes i

4、nto a condenser after leaving the turbine. condensation is effected by the circulation of large quantities of cold water through the tubes of the condenser, thus increasing the expansion ratio of the steam and the consequent efficiency and work output of the turbine. the turbines are connected direc

5、tly to large electricity generators.in turbines the action of the steam is kinetic. there is progressive expansion of the steam from the high pressure and relatively small volume at which it enters the turbine to the low pressure and relatively very great volume at which it leaves.steam is made by h

6、eating water in a boiler. the usual boiler has a furnace in which fuel is burned and the heat given off during combustion is conducted through the metal walls of the boiler to generate steam at a pressure within the boiler vessel .in nuclear plants, steam is generated with the aid of a reator in whi

7、ch the controlled fission of uranium or plutonium supplies the necessary heat for the vaporization of water. thus the reator replaces the steam generator of conventional plants.keywords：turbine, steamfrom reference 2up until now we have been mainly concerned with minimizing the cost of operating a p

8、ower system. an overriding factor in the operation of a power system is the desire to maintain system security. system security involves practices designed to keep the system operating when components fail. for example, a generating until may have to be taken off-line because of auxiliary equipment

9、failure. by maintaining proper amounts of spinning reserve, the remaining units on the system can make up the deficit without too low a frequency drop or need to shed any load. similarly, a transmission line may be damaged by a storm and taken out by automatic relaying. if in committing and dispatch

10、ing generation proper regard for transmission flows is maintained, the remaining transmission lines can take the increased loading and still remain within limit. because the specific times at which initiating events that cause components to fail are unpredictable the system must be operated at all t

11、imes in such a way that the system will not be left in dangerous condition should any credible initiating event occur. since power system equipment is designed to be operated within certain limits, most pieces of equipment are protected by automatic devices that can cause equipment to be switched ou

12、t of the system if these limits are violated. if any event occurs on a system that leaves it operating with limits violated, the event may be followed by a series of further actions that switch other equipment out of service. this is usually referred to as a system blackout.keywords：power system, se

13、curityfrom reference 3system monitoring provides the operators of the power system with pertinent up-to-date information on the conditions on the power system .generally speaking it is the most important function of the three. from the time that utilities went beyond systems of one unit supplying a

14、group of loads, effective operation of the system required that critical quantities be measured and the values of the measurements be transmitted to a central location. such systems of measurement and data transmission, called telemetry systems, have evolved to schemes that can monitor voltages, cur

15、rents, power flows, and the status of circuit breakers switches in every substation in a power system transmission network. in addition, other critical information such as frequency, generator unit outputs and transformer tap positions can also be telemetered. with so much information telemetered si

16、multaneously, no human operator could hope to check all of it in a reasonable time frame. for this reason, digital computers are usually installed in operations control centers to gather the telemetered data, process them, and place them in a data base from which operators can display information on

17、 large display monitors. more importantly, the computer can check incoming information against prestored limits and alarm the operators in the event of an overload or out-of-limit voltage. state estimation is often used in such systems to combine telemetered system data with system models to produce

18、 the best estimate (in a statistical)of the current power system conditions or “state”.keywords：telemeter, estimatefrom reference 4the main objective of production control in power system is to minimize the cost of generated power while maintaining its quality and satisfying the system security cons

19、traints. this implies directly that losses in both the generation and the transmission of electrical energy must be as small as possible. all participating generators are run at high efficiencies, the mix of production resources is exploited economically and the energy is transmitted optimally. prod

20、uction control includes general both active and reactive power. however, the main interest in this type of application has so far been focused mainly on the active part. this is the case in this section also. however, interest for the reactive part is rapidly growing and will soon get a great deal o

21、f action. the activities in the production control field have traditionally been based on planning. this is still the case. the aim is then to break down the overall objective into detailed plans, normally on an hourly basis, that can be carried out by the operator in the control center. thus, sever

22、al steps are taken in a hierarchical scheme to support the operators ambition always to have production resources available to meet the load demand and guide him to operate the generating units so that the most economic alternatives are chosen. the security aspects must also be consisted ,e.g. the s

23、election of production units must not result in line overloads, too high bus voltage etc. if the system suffers the sudden loss of generation, it must be prevented from getting into the alert state for example by activating production reserves. keywords：production control, security2中文翻譯及分析出自文獻(xiàn)1： 在大型

24、火電廠中，蒸汽中儲存的熱能通過汽輪機做功。汽輪機基本上是由軸或者固定在軸承之間封閉在圓柱形汽缸內(nèi)的轉(zhuǎn)自組成。轉(zhuǎn)子由汽輪機汽缸周圍的噴嘴噴出的氣流推動而平穩(wěn)轉(zhuǎn)動。這些噴射蒸汽流沖擊安裝在軸上的葉輪。中心發(fā)電廠應(yīng)用凝汽式汽輪機，使蒸汽離開汽輪機進(jìn)入凝汽器，由凝汽器管束內(nèi)的大量循環(huán)冷卻水進(jìn)行凝汽，這樣就增加了蒸汽的膨脹率和效益，也增加了汽輪機的輸出。汽輪機直接連接大型的發(fā)電機組。 在汽輪機內(nèi)，蒸汽是運動的，它有一個逐漸膨脹的過程：進(jìn)入汽輪機時，蒸汽在高壓下有相對較小的體積，而離開汽輪機時，在低壓下有相對較大的體積。 蒸汽由鍋爐內(nèi)的熱水生成。一般鍋爐有燃燒室，燃料在燃燒室燃燒，燃燒過程中散發(fā)的熱通過鍋

25、爐內(nèi)的金屬壁傳導(dǎo)，在鍋爐內(nèi)產(chǎn)生一定壓力下的蒸汽。在核電廠，借助反應(yīng)堆內(nèi)鈾或钚的裂變提供的熱量來使水汽化產(chǎn)生蒸汽。這樣，反應(yīng)堆就取代了傳統(tǒng)電廠的蒸汽發(fā)生器。關(guān)鍵字：汽輪機，蒸汽出自文獻(xiàn)2：到目前為止，我們一直主要關(guān)心最大限度德降低電力系統(tǒng)的運行成本，電力系統(tǒng)運行中最重要的就是維護(hù)系統(tǒng)的安全。系統(tǒng)安全之際上涉及涉及：當(dāng)系統(tǒng)中部分設(shè)備發(fā)生故障時，系統(tǒng)還能正常運行。例如，一套發(fā)電機組因為附屬設(shè)備發(fā)生故障而不得不停止工作。通過維持適量備用發(fā)電能力，系統(tǒng)內(nèi)仍在工作的發(fā)電機組可以彌補發(fā)電量的不足而不會使頻率下降太多，也不需要拉閘斷電。同樣，一條輸電線可能遭受暴風(fēng)雨而受損，自動中續(xù)保護(hù)器則會使其與電網(wǎng)斷開，如

26、在發(fā)電調(diào)度時，保持對輸電線路的適度關(guān)注，其余的輸電線路就會承擔(dān)相應(yīng)的負(fù)荷，而電力系統(tǒng)仍處于安全。因為使電力系統(tǒng)的設(shè)備發(fā)生故障的始發(fā)事件的特定時間不可預(yù)測，電力系統(tǒng)必須一直以下列方式運行：任何可信始發(fā)事件發(fā)生時，電力系統(tǒng)都不會處于危險狀態(tài)。由于電力系統(tǒng)的設(shè)備設(shè)計成在一定的限度內(nèi)工作，大多數(shù)設(shè)備在超出限度時，自動保護(hù)裝置會使設(shè)備與系統(tǒng)斷開而保護(hù)設(shè)備。假設(shè)系統(tǒng)內(nèi)任何事件使系統(tǒng)超限運行，隨后會產(chǎn)生一系列的反應(yīng)，使其他設(shè)備停止工作。如果這一過程繼續(xù)，整個電力系統(tǒng)或系統(tǒng)大部分可能完全癱瘓。這通常被稱為電力系統(tǒng)斷電。關(guān)鍵字：電力系統(tǒng)，安全出自文獻(xiàn)3： 系統(tǒng)控制功能為電力系統(tǒng)操作人員提供與電力系統(tǒng)相關(guān)的最新狀

27、態(tài)信息。一般而言，它是三個功能中最重要的功能。從電力公司超越一臺機組系統(tǒng)系統(tǒng)供應(yīng)一組負(fù)荷之時起，電力系統(tǒng)有效的運行要求測量最重要的數(shù)據(jù)，并把側(cè)到的數(shù)據(jù)傳送到控制中心。這樣的測量和數(shù)據(jù)傳送的遙測系統(tǒng)已經(jīng)發(fā)展成為可以監(jiān)控電壓、電流、電能流和電力系統(tǒng)輸電網(wǎng)絡(luò)內(nèi)每一變電站的線路斷路器和開關(guān)狀態(tài)的裝置。此外，其他重要性信息，如頻率、發(fā)電機組輸出和變壓器抽頭位置也可以遙測。這么多數(shù)據(jù)同時遙測，操作人員不可能在合理的時間內(nèi)全部核實。因此，通常在運行控制中心安裝數(shù)字計算機來收集、分析遙測數(shù)據(jù)并把數(shù)據(jù)存入數(shù)據(jù)庫。操作人員也可以把信息從數(shù)據(jù)庫調(diào)出并顯示在大屏幕上。更重要的是，計算機可以把輸入數(shù)據(jù)與之前存儲的限制數(shù)

28、據(jù)進(jìn)行對比，并在過載或超限電壓時向操作人員發(fā)出警示。 這樣的系統(tǒng)長應(yīng)用狀態(tài)把遙測系統(tǒng)數(shù)據(jù)與系統(tǒng)模型相結(jié)合，作出現(xiàn)在電力系統(tǒng)狀態(tài)最佳的評估（統(tǒng)計學(xué)意義上的）。關(guān)鍵字：遙測，評估出自文獻(xiàn)4：電力系統(tǒng)內(nèi)生產(chǎn)控制的主要目標(biāo)是：在維持電能質(zhì)量和滿足系統(tǒng)安全要求的條件下，最大限度地降低生產(chǎn)電能的成本。這意味著生產(chǎn)和輸送電能的損耗必須盡可能小。所有參與的發(fā)電機組將高效運轉(zhuǎn)，并以混合方式經(jīng)濟(jì)地開發(fā)利用生產(chǎn)資源和優(yōu)化輸送電能。生產(chǎn)控制一般包括有功功率和無功功率。到目前為止，對這種應(yīng)用的主要興趣仍主要集中在有效功率上，這一節(jié)的內(nèi)容也是如此。但對無功功率的興趣在快速增長，并將極大地重視。生產(chǎn)控制領(lǐng)域的活動傳統(tǒng)上是根

29、據(jù)計劃進(jìn)行的?，F(xiàn)在仍舊如此，目的是把整個計劃分解成比較詳細(xì)的子計劃，一般以小時為基本單位。控制中心的操作人員可以執(zhí)行這種子計劃。因此可以在分級計劃內(nèi)采取若干步驟來支持操作人員的愿望：總有生產(chǎn)資源可以利用來滿足負(fù)荷需要并指導(dǎo)他們以最經(jīng)濟(jì)方式路過負(fù)荷、過電壓等。假設(shè)系統(tǒng)突然失去一些發(fā)電能力，必須啟動備用發(fā)電機組以防止進(jìn)入警戒狀態(tài)。關(guān)鍵字：生產(chǎn)控制，安全3 長難句分析及專業(yè)詞匯a). continuity n. 連續(xù)性b). bearing n. 軸承c). kinetic a. 運動的d). vaporization n. 蒸汽，汽化e). pelton wheel n. 沖擊式水輪機4 中心思想

30、三相系統(tǒng)是目前最常用的發(fā)電和輸電系統(tǒng)。目前發(fā)電的主要方式是火力發(fā)電，水力發(fā)電，核電等，其中火力發(fā)電應(yīng)用最廣泛。電力系統(tǒng)運行時，應(yīng)使任何始發(fā)事件發(fā)生時，電力系統(tǒng)都不會處于危險狀態(tài)。系統(tǒng)的控制功能是電力系統(tǒng)最重要的功能，運行中常將采集到的系統(tǒng)數(shù)據(jù)與系統(tǒng)模型相結(jié)合，以此來評估系統(tǒng)的運行狀態(tài)。5 列出文獻(xiàn)1.王宏文等.自動化專業(yè)英語教程.北京：機械工業(yè)出版社，19982.馮俊寶.電力專業(yè)英語基礎(chǔ).北京：中國電力出版社，20093.馮俊寶等.電力專業(yè)英語基礎(chǔ)學(xué)習(xí)指南.北京：中國電力出版社，20084.劉然等.電力專業(yè)英語（第三版）.北京：中國電力出版社，2010page2. generators and

31、 motors(發(fā)電機和電動機)1.english testfrom reference 1 the basic electrical principle underlying operation of dc generators is called “generator action”. if a length of wire is moved thorough a magnetic field in such a way that the wire cuts between the north and south poles producing the magnetic field, an

32、 electric voltage will be set up in the wire. 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 the wire lengths would be equal to the sun of voltage

33、s set up in the individual lengths wire. “generator action” is the effect whereby the voltage is set up in a moving conductor. in dc generators, the conductors are wound into coils and mounted in slots on the armature or rotating element within the units housing. the end of each coil of conductors a

34、re brought out to one end of the armature where they are connected to individual insulated bars in a assembly of such bars, which is mounted around the armature shaft. this assembly is called the “commutator”, which is required to provided direct-current output from the generator. the wires that com

35、e out of the generator, one for the positive side of the dc output and one for 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. key

36、words：generator, voltagefrom reference 2an electric motor can be reserved by reserving the direction of the current in either its armature or its field coils. if both currents are reserved the motor continues to turn in the same direction, and it follows that the commutator motors described above wi

37、ll work from an ac supply. there are, however, two special kinds of motor that can be used with ac only. the first of these is called a synchronous motor because it synchronizes itself, that is, it keeps in step with the ac supply. the moving part, called the rotor, is a straight bar magnet mounted

38、on a spindle thorough its center between the poles of an electromagnet. when the electromagnet is joined to an ac supply its magnetism reserves regularly each time the current changes direction, and its poles become alternately n and s. the synchronous motor is not self-starting, but if the rotor is

39、 spun round by hand at the correct speed, its s pole is always approaching the upper pole of the electromagnet when this is a n pole. and by the same time electromagnet current has changed the upper pole to a s pole, the rotor has turned so that the n pole is approaching. the magnetic attraction bet

40、ween the opposite poles of the rotor and the electromagnet pulls the rotor round and keeps it moving. the current, synchronous, speed is when the rotor revolves once for each complete cycle of the ac supply, with a 50 cycle ac supply the synchronous motors speed is 50 revolutions per second, that is

41、 3000 revolutions per minute. this kind of motor has a perfectly constant speed as long as the frequency of the ac supply stays constant, and because of this it is used to drive electric clocks. keywords：electric motor, rotorfrom reference 3 synchronous machines can be classified as cylindrical-roto

42、r or salient-pole machines. the cylindrical-rotor construction is used in high steam-turbine-driven generators. the armature windings consist of laminated conductors placed in the sator slots. they are usually 3-phase y-connected windings, and voltages of above 13,800 volts, line to line, are common

43、 in sizes above several thousand kilowatts. the rotor carries the dc field windings. most of the turbine generators being built at present for 60-cps service are 2-pole 3,600-rpm machines. because of the economics of high-speed high-temperature high-pressure steam turbines, much study and some real

44、pioneering work have been devoted to improvements in materials and design of both generators and turbines, and the maximum ratings for which 3,600-rpm machines have been built have approximately doubled during the decade. the advantage of large units are: somewhat increased efficiency, somewhat lowe

45、r capital cost per kilowatt, and the lower plant operating cost because of the greater ease of operating a generating station consisting of a relatively few large units as compared with one consisting of many smaller units. keywords：synchronous machine, sizefrom reference 4 because of the high rotat

46、ional stresses, the rotors of turbine generators must be designed for as small a diameter as is consistent with other requirements. at the same time, limitations are imposed on the axial length of the rotor by vibration considerations. hence the design of the rotor is indeed a difficult problem, and

47、 the design of the whole machine is largely determined by it. stresses are high, operating temperatures are high, and space is cramped. the insulation is subjected to severe rotational stresses, relatively high temperatures, and severe stresses caused by thermal expansion of the coils. these factors

48、 make a low-voltage rotor winding desirable. turbine generators usually are designed for excitation at voltage of 125 to 375 volts. the field current usually is obtained from an exciter coupled to the shaft of the generator. the air gaps of turbine generators usually are much longer than in other ty

49、pes of machines. a long air gap reduces the reactance of the armature wingding and improves voltages regulation and stability. it is also necessary for ventilation. an obvious advantage of a long air gap is that it necessitates a greater field mmf to produce a specified air-gap flux. the cooling pro

50、blem in electrical apparatus in general increases in difficulty with increasing size, because the surface area from which the heat must be carried away increases roughly as the square of the dimensions, while the heat developed by the losses is roughly proportional to the volume and therefore increa

51、ses approximately as the cube of the dimensions. because of their compactness, this problem is a serious one with large turbine generators.keywords：turbine generator, design1. 中文翻譯及分析 出自文獻(xiàn)1： 構(gòu)成直流發(fā)電機運行基礎(chǔ)的基本電氣原理被稱作“發(fā)電機行為”。如果一段導(dǎo)線以切割產(chǎn)生的磁場的n極和s極的磁力線方式通過這個磁場，那么這段導(dǎo)線中就會產(chǎn)生電壓。當(dāng)然，在單獨的一段導(dǎo)線中產(chǎn)生的電壓是很小的。但是，如果大量的導(dǎo)線首

52、尾相連并在磁場中旋轉(zhuǎn)，那么在這一系列導(dǎo)線中產(chǎn)生的電壓將等于在單個導(dǎo)線中產(chǎn)生的電壓的和?！鞍l(fā)電機行為”可以解釋為何電壓會在移動導(dǎo)線中產(chǎn)生。 在直流發(fā)電機中，導(dǎo)線纏繞成線圈，并安在電樞線槽內(nèi)或電機殼內(nèi)的旋轉(zhuǎn)部件上。每個線圈導(dǎo)線的末端連接到電樞一端的單獨絕緣的母線上；這些母線構(gòu)成的匯流排安裝在電樞軸上。這個裝置叫“換向極”，用來為發(fā)電機提供直流輸出。這些從發(fā)電機出來的導(dǎo)線，一條用作直流電輸出的正極，另一條用作負(fù)極，它們在發(fā)電機內(nèi)連接到換向器的電刷上。這些電刷從換向器獲取電流，并將其傳送到發(fā)電機供給的電路中去。關(guān)鍵字：發(fā)電機，電壓出自文獻(xiàn)2 通過改變電樞或勵磁線圈的電流方向，電動機會逆向轉(zhuǎn)動。如果兩邊

53、電流同時逆轉(zhuǎn)，那么發(fā)電機仍會向同一個方向轉(zhuǎn)動，因此得出，交流電將驅(qū)動上文所描述的整流式電動機旋轉(zhuǎn)。但是，有兩種特別的電動機只能用交流電作為電源。第一種是同步電動機，因為它使自身同步，也就是說，它和交流電保持同步。轉(zhuǎn)動部分即轉(zhuǎn)子，是直條形磁極，它安裝在從電磁鐵磁極中心穿過的主軸上。當(dāng)電磁鐵連接到交流電時，它的磁場方向隨電流方向改變而逆轉(zhuǎn)，其磁極交替變成n和s極。同步電動機不是自啟動的，但如果轉(zhuǎn)子以合適的速度用手旋轉(zhuǎn)，當(dāng)它s極總是接近電磁鐵的上部磁極時，這是n極。當(dāng)電磁鐵電流改變，使得上邊的磁極轉(zhuǎn)向s極時，轉(zhuǎn)子也改變，所以n極在靠近。轉(zhuǎn)子和電磁鐵直接相反的兩級之間的磁吸力拉動轉(zhuǎn)子旋轉(zhuǎn)，并使它保持運

54、動。合適的轉(zhuǎn)速（同步轉(zhuǎn)速）使轉(zhuǎn)子在交流電一個周期，完成完整的一圈旋轉(zhuǎn)。交流電的頻率是50hz，那么同步電動機的速度就是50次每秒，也就是3000轉(zhuǎn)每分鐘。只要交流電供應(yīng)保持頻率恒定，此類型的電動機速率也就恒定，所以常用來驅(qū)動電子時鐘。關(guān)鍵字：電動機，轉(zhuǎn)子出自文獻(xiàn)3同步電機可分為圓柱式轉(zhuǎn)子電機和凸極電機。圓柱式轉(zhuǎn)子結(jié)構(gòu)用于高速汽輪發(fā)電機中。其電樞繞組由置于定子槽內(nèi)的分層導(dǎo)體組成，一般為三相y連接的繞組，而13800v以上的線電壓通常用于數(shù)千千瓦以上的容量。轉(zhuǎn)子裝有直流勵磁繞組，目前制造的用于60hz的大多數(shù)汽輪發(fā)電機具有2極3600r/min的電機。由于高速高溫高壓汽輪機的經(jīng)濟(jì)性，已進(jìn)行了許多研

55、究和具有開拓性的工作以改進(jìn)發(fā)電機和汽輪機的材料和設(shè)計。而近十年，3600r/min的電機的最大容量已接近翻一番。大型設(shè)備的優(yōu)點是：效率有所增加，每千瓦的投資費用有所減小，同時設(shè)備運行費用降低。這是因為由相對較少的大容量機組組成的發(fā)電站運行起來比由較多容量機組組成的電站要簡單。關(guān)鍵字：同步電機，容量出自文獻(xiàn)4：由于旋轉(zhuǎn)應(yīng)力高，汽輪發(fā)電機的轉(zhuǎn)子直徑在滿足其他要求時應(yīng)盡量設(shè)計得小一些。同時從震動考慮，轉(zhuǎn)子的軸向長度受到限制。因此轉(zhuǎn)子的設(shè)計實在是一件困難的事，而整個電機的設(shè)計基本上受它限制，困難表現(xiàn)在應(yīng)力高，運行溫度高及空間限制嚴(yán)格。絕緣承受嚴(yán)重的旋轉(zhuǎn)應(yīng)力、較高的溫度以及線圈膨脹而引起的嚴(yán)重應(yīng)力。這些

56、因素使它希望低壓的轉(zhuǎn)子繞組。汽輪發(fā)電機的勵磁電壓通常設(shè)計成125-375v。勵磁電流一般從與發(fā)電機共軸連接的勵磁機中獲得。汽輪發(fā)電機的空氣氣隙通用比其他類型的電機的大得多。大的空氣氣隙會減小電樞繞組電抗，因而改善電壓的調(diào)整率和穩(wěn)定度。大的氣隙也是通風(fēng)的需要。大氣隙的一個顯著的缺點是，它需要較大勵磁磁動勢以產(chǎn)生規(guī)定的氣隙磁通。通常，隨著容量的增加電氣裝置的冷卻苦難也增加，這是因為散熱表面大約按尺寸的平方增加，而損耗產(chǎn)生的冷卻大約正比于體積，因此近似地按尺寸的平方增加。由于尺寸緊縮，所以這對大型發(fā)電機來說是一個嚴(yán)重的問題。關(guān)鍵字：汽輪發(fā)電機，設(shè)計3 長難句分析及專業(yè)詞匯a).rotate v.旋轉(zhuǎn)

57、b).excitation n.勵磁c).revolution n.旋轉(zhuǎn)一周d).in parallel 并聯(lián)e).flux n.磁通f).polyphase a.多相的4 中心思想發(fā)電機分為交流發(fā)電機和直流發(fā)電機，分別將機械能轉(zhuǎn)化為交流電能與直流電能。汽輪發(fā)電機的轉(zhuǎn)子設(shè)計很困難，而整個電機的設(shè)計受其限制，在各種因素下轉(zhuǎn)子直徑應(yīng)盡量設(shè)計得小一些。同步電動機交流電保持同步，速率恒定，所以常用來驅(qū)動電子時鐘。5 列出文獻(xiàn)1.王宏文等.自動化專業(yè)英語教程.北京：機械工業(yè)出版社，19982.馮俊寶.電力專業(yè)英語基礎(chǔ).北京：中國電力出版社，20093.馮俊寶等.電力專業(yè)英語基礎(chǔ)學(xué)習(xí)指南.北京：中國電力出

58、版社，20084.劉然等.電力專業(yè)英語（第三版）.北京：中國電力出版社，2010page3. electrical energy transmission（電能輸送）1.english testfrom reference 1 when lightning makes a direct hit on a transmission line, it deposits a large electric change, producing an enormous overvoltage between the line and ground. the dielectric strength of air is immediately exceeded and a flashover occurs. the line diachanges itself and overvoltage disappears in typically less than 50us. unfortunately, the act between the line