電氣畢業(yè)設(shè)計外文翻譯

1、山東建筑大學畢業(yè)設(shè)計外文文獻及翻譯本科畢業(yè)設(shè)計外文文獻及譯文文獻、資料題目：special english for architectural electric engineering and automation文獻、資料來源：期刊（著作、網(wǎng)絡等）文獻、資料發(fā)表（出版）日期：2006.4院 （部）： 信息與電氣工程學院學院專 業(yè)： 電氣工程與自動化班 級： 電氣093姓 名： 孫德藝學 號： 2009081102指導教師： 陳紅艷翻譯日期： 2013.6.30外文文獻一：transformer one of the most valuable apparatus in electric po

2、wer system is the transformer, for it enables us to utilize different voltage levels across the system for the most economical value. generation of power at the synchronous machine level is normally at a relatively low voltage，which is most desirable economicallystepping up of this generated voltage

3、 to high voltage，extra-high voltage or even to ultra-high voltage is done through power transformers to suit the power transmission requirement to minimize losses and increase the transmission capacity of the linesthis transmission voltage level is then stepped down in many stages for distribution a

4、nd utilization purposes a transformer is a static device for transferring electric energy from one circuit to another electromagnetically，that is，by induction instead of by conductionits usual function is to transfer energy between circuits of different voltagea transformer has a magnetic core on wh

5、ich there are two or more windingsthese windings are insulated from each other and from groundin autotransformers，however，the windings are connected togetherthe assembly of core and coils is normally insulated and cooled by immersion in mineral oil or other suitable liquid within an enclosing tankco

6、nnection to the windings is by means of insulating bushings，usually through the cover.the “ratio of transformation” is determined by the relative number of turns in each of he windingsthis is known as the “turn ratio” and it is the ratio of the no-load voltageswhen the unit is carrying load, the rat

7、io of the actual voltages is slightly different because of the drop caused by the flow of 1oad current through the impedance of the transformer windingsat rated load, this drop is known as the voltage regulation. the amount of voltage drop varies with the power factor of the output even when the kil

8、ovolt-amperes remain constantpractically all power transformers and many distribution transformers have taps in one or more windings for changing the turn ratiochanging the ratio is desirable for two reasons to compensate for varying voltage drop in the system and to assure that the transformer oper

9、ates as nearly as possible at the correct core densityfor the latter purpose, the taps should be in the winding subject to the voltage variation. de-energized tap changers are used when it is expected that the ratio will need to be changed only infrequently, because of load growth or some seasonal c

10、hangethe desired tap is selected by means of a ratio adjuster(no load taps)load tap changer(ltc)is used when changes in ratio may be frequent or when it is undesirable to de-energize the transformer to change a tapit seldom makes much difference to the user which winding or windings are tapped；there

11、fore，the choice is usually made by the designer on the basis of cost and good design. both winding current and voltage must be considered when applying ltc equipmenthigh voltage and high current applications require special considerations to arrive at an optimum location for the ltc equipmentstep do

12、wn units usually have ltc in the low-voltage winding and de-energized taps in the high voltage windingwhen energy is to be transferred between two circuits of nearly the same voltagethe use of autotransformers affords cost savings over two-winding unitsthe nearer the voltages are to each other, the

13、smaller will be the autotransformer per kilovolt-ampere of output，and the greater the savingsthe simplicity of phasing out systems has increased its usemost autotransformers are y-connected，and it has been a standard american practice to add a low capacity, delta windingthis is frequently referred t

14、o as a “delta tertiary“its primary purpose has been to provide an internal path for the third harmonic currents (required for excitation)，thus reducing those currents on the power systemit also helps to stabilize the neutral and to ground the system betterin recent years，the use of shielded telephon

15、e cable has reduced the requirements for the delta tertiary. because an autotransformer does not afford electrical separation between the two circuits, disturbances originating on one circuit can be communicated to the otherthis difficulty is minimized by solidly grounding the neutral of the autotra

16、nsformer. solidly grounding the neutral，however, causes(among other things)current of short-circuit magnitude to flow through the delta-connected tertiary winding during ground faults on either system. autotransformers are not inherently self-protecting and, therefore，all windings must be examined f

17、or mechanical strength as applied to the system where they will be used . tertiaries are normally 35of the physical size of the largest winding of the autotransformer, unless otherwise specified by the user.the bulk of a11 transformers，except for large extra-high voltage(ehv)and distribution units a

18、re three-phase units in the early days of the industry，it was almost universal practice in the united states to use three single-phase units connected in a three-phase bankinsulation clearances and shipping limitations for certain large ehv units now require this designthe distribution systems serve

19、 mainly single-phase loads in residential areas and are served from single-phase transformers中文譯文一： 變壓器 在電力系統(tǒng)中最有價值的一個裝置是變壓器,因為它使我們能夠在系統(tǒng)中利用不同的電壓水平獲得最經(jīng)濟的價值。同步電機的發(fā)電電壓水平通常是在一個相對較低的電壓,這是最令人滿意也是最經(jīng)濟的。把發(fā)電電壓升高到高電壓,超高壓甚至超高電壓是通過電源變壓器實現(xiàn)的,這樣可以適應電力傳輸要求,減少電壓損失,提高線路的傳輸容量。在不同的階段，我們可以根據(jù)配電和使用目的的要求把高電壓通過變壓器降到低電壓。 一個變壓器

20、是一個靜態(tài)裝置，因為電能量從一個電路轉(zhuǎn)移到另一個電路是通過電磁的形式實現(xiàn)的,也就是說,能量的轉(zhuǎn)移是通過感應而不是通過傳導。變壓器通常的功能是傳遞不同電壓等級電路之間的能量。 變壓器有一個磁芯，磁芯上有兩個或兩個以上的繞組，這些繞組相互之間是絕緣的并且與大地也是絕緣的。 然而自藕變壓器中的繞組是直接連在一起的的。 磁芯和繞組的組裝通常是在密閉容器內(nèi)進行的并且浸沒在礦物油或其他適當?shù)囊后w中。線圈的連接是通過絕緣套管,通常穿過表面?！白儔罕取笔怯擅總€繞組上線圈的相對匝數(shù)決定的。我們稱為“匝數(shù)比”,這也是空載電壓比。當變壓器承載負荷時,實際電壓的比例略有不同,因為當負載電流通過變壓器時會因為繞組阻抗而

21、使電壓產(chǎn)生降落。在額定負載下,這種電壓降落被稱為“電壓調(diào)整”。 電壓降落的大小隨輸出的功率因數(shù)的變化而變化即使總的視在功率保持不變。 幾乎所有的電力變壓器和輸電變壓器在一個或多個線圈上都有改變變壓器變比的開關(guān)。改變變比有兩個令人滿意的理由：補償系統(tǒng)中變化的電壓降落以及確保變壓器盡可能的在正確的中心密度下操作。為了達到后邊的目的，改變變比的開關(guān)通常放在變壓器的繞組中并且受電壓變化的控制。當變比不經(jīng)常改變時，例如負荷的增加或者季節(jié)的變化，我們常用斷距抽頭轉(zhuǎn)換開關(guān)。 理想的開關(guān)是由比例調(diào)節(jié)器選擇的。當變比變化比較頻繁或者不希望斷開變壓器去改變抽頭時，我們常用負載抽頭轉(zhuǎn)換開關(guān)(ltc)。 當線圈或線圈

22、組都是抽頭時對使用者這幾乎沒有任何區(qū)別；因此,設(shè)計師通常根據(jù)成本和良好的設(shè)計來做出選擇。應用ltc設(shè)備時繞組電流和電壓都是必須考慮的。高電壓和大電流在應用中需要特殊考慮才能達到負載抽頭轉(zhuǎn)換開關(guān)（ltc）設(shè)備的最佳使用條件。在降壓變壓器中，低壓繞組通常用ltc（負載抽頭轉(zhuǎn)換開關(guān)），高壓繞組通常用斷距抽頭轉(zhuǎn)換開關(guān)。當兩個具有相同的電壓的電路之間轉(zhuǎn)移能量時,使用自耦變壓器要比使用兩個繞組單元更能夠節(jié)約成本。兩個電路的電壓越接近,自耦變壓器輸出的每千伏安越小,也就越節(jié)約成本。一些簡單落后的系統(tǒng)往往常用它。很多自耦變壓器是星形連接,這已經(jīng)成為一個標準，但美國人嘗試采用低容量三角形連接的自耦變壓器。這是經(jīng)

23、常被稱為是一個“三角洲三級“牽引,主要目的是為三次諧波(用來激發(fā))提供一個內(nèi)部路徑,從而減少在電力系統(tǒng)的諧波。這也有助于穩(wěn)定中性點并且使接地系統(tǒng)更好的工作。在最近幾年,屏蔽電話電纜的使用已經(jīng)降低了對三角洲三級的要求。？因為一個自耦變壓器不負擔兩個電路之間的電氣隔離, 來源于一個電路的干擾可以傳達到另一個電路。這一困難可以通過將自耦變壓器的中性點直接接地來解決。然而,中性點直接接地,在系統(tǒng)發(fā)生接地故障時會(在其他事物之中)引起短路電流流過三角接法的第三相繞組。第三繞組的物理尺寸通常為自耦變壓器最大的繞組的35%,除非用戶另有指定。自耦變壓器就不具有自我保護的功能,因此, 所有的繞組在使用之前都必

24、須經(jīng)過機械強度檢查以確定是否適用于該系統(tǒng)。？除了大型超高壓(超高壓)和配電設(shè)備，大部分變壓器都是三相的。在美國早期的工業(yè)中, 把三個單相單位連接成一個三相的組合設(shè)備是一個非常普遍的經(jīng)驗。某些大型超高壓單位的絕緣間隙和運輸限制現(xiàn)在就需要這個設(shè)計。配電系統(tǒng)主要服務于居民區(qū)的單相負載并且電能是引自單相變壓器。外文文獻二： selection and cooling of power transformerthe selection of the transformer can have a major impact on the cost a substation，since the transfo

25、rmer represents the major cost itemnameplate rating is only a guide to transformer application，and should only be used as a first step in the selection process. the transformer is available as a self-cooled unit，or it can be purchased with additional steps of forced cooling that use fan or fans and

26、oil pumpstransformer ratings can be increased from 25 to 66 by the addition of fans and pumpsthe nameplate rating is based on a continuous load producing a 55 to 65 conductor temperature rise over ambient. since many transformers do not carry continuous loads，advantage can be gained from the thermal

27、 time lag to carry higher peak loads without exceeding the temperature limits .transformer ratings are based on the assumption that only an extremely slow deterioration of insulation will take place with normal operationa substantial increase in rating can be achieved by accelerating the loss of ins

28、ulation lifethis increase in rating might approach 200for an hour or two, and approximately 120for 24 hoursfor substations that are designed to carry full load under the outage of any one transformer, a high emergency rating for a 24-hour period (e.g. until the failed unit can be replaced) could mea

29、n the selection of smaller transformers and a substantial saving in substation cost the selection of the transformer should involve a careful evaluation of a number of other factors： (1)impedances should be selected considering their effect on short-circuit duties and low-side breaker ratings both f

30、or initial and future station developmentsin addition，impedance is important to achieve a proper load division in the parallel operation of transformers. (2)no load tap ranges should be selected to provide an adequate low-side bus voltage.(3)if the high-side or low-side voltages vary over a wide ran

31、ge during the load cycle, it may be necessary to provide bus regulationthe actual regulation can be calculated using the system and load characteristicsif regulating equipment is needed，it may be desirable to provide it in the transformer by using load tap changer(ltc) equipment. if the need for bus

32、 regulation is not presently evident, but may be required in the future, it may be economical to leave space in the station for future regulators, and buy transformers without ltc equipment.a great many transformers, including all the large ones and all the high voltage ones are immersed in mineral

33、oil which serves the double purpose of cooling and insulating the windings. small transformers have enough tank surface to radiate a11 the heat caused by their losses without exceeding the permissible temperature riseas size increases，the losses increase faster than the tank surface which soon becom

34、es inadequatevarious methods have been developed to get the heat out of the tank more effectivelylarge power transformer being built today are commonly of the forced-oil-cooled typein this design the oil is pumped both through the external cooling devices(air or water heat-exchangers)and through int

35、ernal channels that are located nearest the points where the heat is generatedthus the transfer of heat to and from the oil is far more effective than in the plain self-cooled or fan-cooled unit where the oil is allowed to circulate by convection. when oil-to-air heat exchanger(a group fans on each

36、radiator)is used，this cooling type is designated as type of foawhile oil-to-water heat exchanger is used，it is called fowfor applications where any liquid，even a nonflammable one，is objectionable，the dry-type transformer is usedthe ventilated dry-type unit is cooled by a continuous natural draft of

37、air and consequently is not suitable for locations where the air is wet or dirty. for these locations a completely enclosed unit，the sealed dry-type，is available，having a core-and-coil in a tank that is sealed and filled with an insulating gas. dry-type transformers are completely nonflammable，using

38、 organic material such as epoxy resin.中文譯文二： 電力變壓器的選擇和冷卻 變壓器的選擇對變電所的建造成本具有重大影響,因為變壓器是主要的成本項目。銘牌定額只是變壓器應用的指南,它只應該用作變壓器選擇過程的第一步。變壓器可以是自冷式單位,也可以購買額外的冷卻裝置,如強制冷卻風機或機組和柴油泵。根據(jù)額外的冷卻機組和柴油泵，變壓器評級可以從25%增加到66%。銘牌評級是基于連續(xù)負荷產(chǎn)生超過環(huán)境55到65導體溫升而評定的。？因為很多變壓器不帶連續(xù)負載,優(yōu)勢可以獲得從熱滯后時間進行更高的高峰負荷而不超過溫度限制。變壓器的評級是基于假設(shè)：正常操作下的絕緣老化只是一個

39、極其緩慢的過程。通過加速絕緣老化的進程可以大幅度的提高評定等級。在一兩個小時左右評級可能增長接近200%,而在在二十四小時左右評級則增長大約120%。因為變電站的設(shè)計要保證在任何一個變壓器斷電的情況下都要滿足全負荷運行，為24變電站設(shè)計將滿載在停機的任何一個變壓器,因此在二十四小時內(nèi)的較高的緊急評級(例如直到失敗的單位可以更換)可能意味著選擇較小的變壓器和節(jié)約大量的變電所成本。 變壓器的選擇應該涉及對其他影響因素的審慎評估:(1)阻抗應該被選擇的考慮到他們對短路職責和下部斷路器評級的影響對初始和未來空間站發(fā)展。此外,阻抗在并行變壓器的操作中獲得一個合適的負載也是十分重要的.(2)無載分接范圍應

40、該選擇提供一個足夠的下部總線電壓。(3)如果高壓側(cè)或低壓側(cè)電壓在負載周期內(nèi)變化很大的話,可能有必要提供總線監(jiān)管。通過系統(tǒng)和負載特性實際監(jiān)管和控制是可以被計算和描繪的。如果調(diào)節(jié)設(shè)備是必要的,在變壓器內(nèi)使用負載抽頭轉(zhuǎn)換開關(guān)(ltc)設(shè)備來提供監(jiān)管是可取的。如果需要總線監(jiān)管目前是不需要的,但可能在未來需要的,那么在變電站預留未來安裝設(shè)備的空間并且購買沒有l(wèi)tc設(shè)備的變壓器是十分經(jīng)濟的。許多變壓器,包括所有的大體積的和所有的高電壓的變壓器都是沉浸在礦物油,礦物油有雙重目的：冷卻和絕緣繞組。小變壓器有足夠的容器表面輻射a11熱引起的損失而不超過容許溫度上升范圍。隨著體積的增加,損失增加的速度會加快，這時

41、容器表面會變得不適宜。很多的方法已經(jīng)被改進以使的容器的散熱更有效。今天一般建造的大型電力變壓器都是強制循環(huán)油冷卻類型的。在這個設(shè)計中礦物油通過油泵不僅流進外部冷卻設(shè)備(空氣或水熱交換器)，而且流過內(nèi)部最靠近熱源的凹槽。因此通過礦物油對熱量進行轉(zhuǎn)移的方式要比一般的自冷裝置和風冷裝置要有效的多,因為油是允許通過對流循環(huán)的。當油空氣熱交換器(在每個散熱器有一組風機)被使用時,這種冷卻類型被指定為foa。當油水熱交換器被使用時，則被稱為fow。因為無論變壓器是采用何種液體都是不受歡迎的，即使這種液體不易燃，所以干式變壓器得到普遍的應用。通風式的干式變壓器通常是通過自然風來使變壓器冷卻的，所以這種變壓器

42、不適于潮濕和惡劣的環(huán)境。如果鐵芯和線圈是在一個充滿絕緣氣體的封閉裝置中則干式變壓器在潮濕惡劣環(huán)境中是完全可以正常運行的的。干式變壓器是完全不燃燒的，因為它使用了有機材料如環(huán)氧樹脂。外文文獻三：circuit breakswithin a few years of the introduction of the fuse，the growing electrical industry startedlooking for an alternative method of providing protection for electric circuitsthey wanted a device

43、that would not be destroyed by its operation，that could simply be reset to restore power, and that could also be used as a means of switching for the circuitout of this development work came the circuit breakerwhich is an electromechanical devicethe circuit breaker is defined as a device designed to

44、 open and close a circuit by non-automatic means and to open the circuit automatically on a predetermined over-current without injure to itself when properly applied within its rating. as with other equipment，circuit breakers are divided into those rated for 1 000 volts and less and those rated for

45、more than 1000 voltslow-voltage circuit breakers were also divided into two distinct categories，molded-case and power typeshowever，in the past few years the distinction between these two types has become less clea-cut as a new type of encased breaker are universally operated in air, so it is not nec

46、essary to designate them as air circuit breakers as this understoodmedium and highvoltage breakers，on the other hand，use mediums other than air in which to open the circuit and therefore must be designated as being air, gas，and so on apart from having different voltage and continuous current ratings

47、breakers have widely different interrupting ratings，response characteristics，and methods of operationthe proper application of circuit breakers requires a good knowledge of all the characteristics and options available for each typethe simplest circuitopening device is the manually operated knife sw

48、itchthis switch has the basic parts required of any circuitopening device：a fixed contact, a moving，an operating handle，and a baseplate or flamehowever as anyone who has opened a knife switch under load has witnessed，there is a luminous discharge drawn between the separating contacts of the switchth

49、is discharge is called an arc，and it consists of a stream of positive and negative ions. the current flowing in a circuit cannot be instantaneously interruptedas a result，the arc continues until the switch contacts have separated far enough to finally extinguish the arcthe arc can make the opening o

50、f the switch very unsafe and unreliable when interrupting a circuit breaker must provide a safer and more reliable interrupting action. the following are the means by witch lowvoltage circuit breakers can be made to safely interrupt large fault currents with a minimum of contact damage 1fast speed o

51、f operationthe duration and severity of an arc depends in part on the speedwith witch the contacts can be separated，therefore powerful spring are used to rapidly force thecontacts openthese springs are compressed (charged)during the closing operationthe breaker contacts are then mechanically held cl

52、osed and are released by a separate trip mechanismanoperator can initiate the opening of the breaker but has no control over the speed with which thecontacts separate 2use of arcing contactsthe arc burn can cause pitting，which eventually affects the abilityof the contacts to carry the load current w

53、hen closedto offset this, two parallel sets of contacts are used for each pole of the breaker，a main current carrying set and an auxiliary or arcing setwhen the breaker is tripped open, the main contacts separate first，transferring the current flow to the arcing contactsthe arcing contacts then sepa

54、rate a split second late，drawing the arc between them and leaving the main contacts free of any arcingthis allows the surfaces of the main current carrying contacts to be made of highconductivity metal such as silver，the surfaces of the arcing contacts are then made of a tougher alloy better able to

55、 withstand the effects of arcing 3use of arc chutes parallel plates enclosed in the form of a chute are mounted directly above the arcing contactsas the arcing contacts separate, the resulting are creates a strong magnetic field that forces the arc upward into the platesthe arc stream is then broken

56、 into a series of small arcs，which are quickly cooled，deionized，and extinguishedthe ionized gases created by the are stream must be deionized before they are expelled from the arc chute；otherwise，secondary arcing could occur between the line side terminals of the breaker, which are still energized中文

57、譯文三：斷路器 在引入保險絲的幾年內(nèi),越來越多的的電力企業(yè)開始尋找一個可替代的保護電氣電路的方法。他們想要一個裝置,不會因為它的操作而被破壞,可能只是恢復供電,也可以用來作為一種電路轉(zhuǎn)換的手段。斷路器，作為一種機電設(shè)備，就是這種發(fā)展的成果。斷路器被定義為這樣的一種裝置：可以通過非自動的方式閉合或斷開電路，也可以在正確應用其評級并且自身不被破壞的情況下根據(jù)電路中的過電流自動的斷開電路。 與其它設(shè)備類似,斷路器分為額定1 000伏特,少許被認為超過1000伏低。壓斷路器也分為兩個不同的類別,塑殼和萬能式。然而,在過去的幾年中這兩個類型之間的區(qū)別已經(jīng)變得不那么明確，因為一種新型的微型斷路器是通常操作

58、在空氣的,所以不需要將它視為空氣斷路器。另一方面,中壓和高壓斷路器使用空氣外的其他的介質(zhì)斷開電路,因此必須指被整定為空氣、瓦斯等其他斷路器一樣。 與其它設(shè)備類似,斷路器分為額定1 000伏特,少許被認為超過1000伏低。壓斷路器也分為兩個不同的類別,塑殼和萬能式。然而,在過去的幾年中這兩個類型之間的區(qū)別已經(jīng)變得不那么明確，因為一種新型的微型斷路器是通常操作在空氣的,所以不需要將它視為空氣斷路器。另一方面,中壓和高壓斷路器使用空氣外的其他的介質(zhì)斷開電路,因此必須指被整定為空氣、瓦斯等其他斷路器一樣。除了有不同的電壓和不間斷電流額定值，斷路器有廣泛不同的分斷能力、響應特性和運行方式，正確的應用斷路器需要深入理解斷路器的特點并且對斷路器的設(shè)置要通用。 電路中的電流不能在瞬間打斷。因此,電弧會持續(xù)存在直到開關(guān)觸頭分離的足夠遠,直到最終熄滅電弧。最簡單的斷路設(shè)備是手動刀開關(guān)。這個開關(guān)有任何短路設(shè)備都需要的基本組件:一個固定的觸頭,一個移動的觸頭,一個操作手柄和一個冷卻基板。然而，如果在帶負載的情況下打開刀開關(guān),在開關(guān)的分斷觸點之間會有發(fā)光放電。這放電稱為電弧弧,它由大量的的正負離子組成。電路中的電流不能在瞬間打斷。因此,電弧會持續(xù)存在直到開關(guān)觸頭分離的足夠遠,直到最終熄滅電弧。 電弧會使開關(guān)的開斷變得很不