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1、<p>  General Requirements to Construction of Substation</p><p>  Substations are a vital element in a power supply system of industrial enterprises.They serve to receive ,convert and distribute electri

2、c energy .Depending on power and purpose ,the substations are divided into central distribution substations for a voltage of 110-500kV;main step-down substations for110-220/6-10-35kV;deep entrance substations for 110-330

3、/6-10Kv;distribution substations for 6-10Kv;shop transformer substations for 6-10/0.38-0.66kV.At the main step-down substations, the energy rece</p><p>  Central distribution substations receive energy from

4、power systems and distribute it (without or with partial transformation) via aerial and cable lines of deep entrances at a voltage of 110-220kV over the enterprise territory .Central distribution substation differs from

5、the main distribution substation in a higher power and in that bulk of its power is at a voltage of 110-220kV;it features simplified switching circuits at primary voltage; it is fed from the power to an individual object

6、 or reg</p><p>  Step-up transformer substations are used at power plants for transformation of energy produced by the generators to a higher voltage which decreases losses at a long-distance transmission .C

7、onverter substations are intended to convert AC to DC (sometimes vice versa) and to convert energy of one frequency to another .Converter substations with semiconductor rectifiers are convert energy of one frequency to a

8、nother .Converter substations with semiconductor rectifiers are most economic. Distributio</p><p>  Depending on location of substations their switch-gear may be outdoor or indoor. The feed and output lines

9、at 6-10kV substations are mainly of the cable type .at 35-220kV substations of the aerial type .When erecting and wiring the substations ,major attention is given to reliable and economic power supply of a given producti

10、on.</p><p>  Substations are erected by industrial methods with the use of large blocks and assemblies prepared at the site shops of electric engineering organizations and factories of electrical engineering

11、 industry .Substations are usually designed for operation without continuous attendance of the duty personnel but with the use of elementary automatic and signaling devices.</p><p>  When constructing the st

12、ructural part of a substation .it is advisable to use light-weight industrial structures and elements (panels ,floors ,etc.) made of bent sections .These elements are pre-made outside the erection zone and are only assem

13、bled at site .This considerably cuts the terms and cost of construction.</p><p>  Basic circuitry concepts of substations are chosen when designing a powersupply system of the enterprise .Substations feature

14、 primary voltage entrances .transformers and output cable lines or current conductors of secondary voltage .Substations are mounted from equipment and elements described below .The number of possible combinations of equi

15、pment and elements is very great .Whenelaborating a substation circuitry ,it is necessary to strive for maximum simplification and minimizing the number of</p><p>  When designing transformer substations of

16、industrial enterprises for all voltages , the following basic considerations are taken into account:</p><p>  1. Preferable employment of a single-bus system with using two-bus systems only to ensure a relia

17、ble and economic power supply;</p><p>  2. Wide use of unitized constructions and busless substations;</p><p>  3.Substantiated employment of automatics and telemetry ;if the substation design d

18、oes not envisage the use of automatics or telemetry ,the circuitry is so arranged as to allow for adding such equipment in future without excessive investments and re-work.</p><p>  4.Use of simple and cheap

19、 devices-isolating switches ,short-circuiting switches ,load-breaking isolators ,fuses ,with due regard for their switching capacity may drastically cut the need for expensive and critical oil ,vacuum ,solenoid and air s

20、witches .Substation and switch-gear circuitries are so made that using the equipment of each production line is fed from individual transformers ,assemblies ,the lines to allow their disconnection simultaneously with mec

21、hanisms without disrupting operatio</p><p>  When elaborating circuitry of a substation, the most vital task is to properly choose and arrange switching devices(switches ,isolators ,current limiters ,arreste

22、rs ,high-voltage fuses).The decision depends on the purpose ,power and significance of the substation.</p><p>  Many years ago, scientists had very vague ideas about electricity. Many of them thought of it a

23、s a sort of fluid that flowed through wires as water flows through pipes, but they could not understand what made it flow. Many of them felt that electricity was made up of tiny particles of some kind ,but trying to sepa

24、rate electricity into individual particles baffled them.</p><p>  Then, the great American scientist Millikan, in 1909,astounded the scientific world by actually weighing a single particle of electricity and

25、 calculating its electric charge. This was probably one of the most delicate weighing jobs ever done by man,for a single electric particle weighs only about half of a millionth of a pound. To make up a pound it would tak

26、e more of those particles than there are drops of water in the Atlantic Ocean.</p><p>  They are no strangers to us, these electric particles, for we know them as electrons. When large numbers of electrons b

27、reak away from their atoms and move through a wire,we describe this action by saying that electricity is flowing through the wire.Yes,the electrical fluid that early scientists talked about is nothing more than electrica

28、l flowing along a wire.</p><p>  But how can individual electrons be made to break away from atoms? And how can these free electrons be made to along a wire? The answer to the first question lies in the stru

29、cture of the atoms themselves. Some atoms are so constructed that they lose electrons easily. An atom of copper, for example ,is continually losing an electron, regaining it(or another electron),and losing it again. A co

30、pper atom normally has 29 electrons, arranged in four different orbits about its nucleus. The inside orbit</p><p>  Consequently,in a copper wire free electrons are floating around in all directions among th

31、e copper atoms.Thus, even through the copper wire looks quite motionless to your ordinary eye, there is a great deal of activity going on inside it. If the wire were carrying electricity to an electric light or to some o

32、ther electrical device, the electrons would not be moving around at random. Instead, many of them would be rushing in the same direction-from one end of the wire to the other.</p><p>  This brings us to the

33、second question .How can free electrons be made to move along a wire? Well ,men have found several ways to do that .One way is chemical. Volta,s voltaic pile,or battery, is a chemical device that makes electricity(or ele

34、ctrons)flow in wires. Another way is magnetic. Faraday and Henry discovered how magnets could be used to make electricity flow in a wire.</p><p><b>  Magnets</b></p><p>  Almost ever

35、yone has seen horseshoe magnets-so called because they are shaped like horseshoes. Probably you have experimented with a magnet, and noticed how it will pick up tacks and nails, or other small iron objects. Men have know

36、n about magnets for thousands of years.</p><p>  Several thousand years ago, according to legend, a shepherd named Magnes lived on the island of Crete, in the Mediterranean Sea .He had a shepherds crook tipp

37、ed with iron. One day he found an oddly shaped black stone that stuck to this iron tip.Later, when many other such stones were found, they were called magnets(after Magnets).These were natural magnets.</p><p&g

38、t;  In recent times men have learned how to make magnets out of iron. More important still, they have discovered how to use magnets to push electrons through wires-that is, how to make electricity flow. Before we discuss

39、 this, there arecertain characteristics of magnets that we should know about.If a piece of glass is laid on top of a horse- shoes magnet, and if iron filings are then sprink ledon the glass, the filings will arrange them

40、selves into lines. If this same thing is trid with a bar magnet(</p><p>  Of course, electrons are not really flowing in the bar magnet, but they are in motion, circling the nuclei of the iron atoms. However

41、, in the magnet, circling thelined up in such a way that their electrons are circling in the same direction. Perhaps a good comparison might be a great number of boys whirling balls onstrings in a clockwise direction aro

42、und their heads.</p><p>  變電站建設(shè)的一般要求</p><p>  變電站(所)在電源系統(tǒng)的工業(yè)企業(yè)是一個(gè)至關(guān)重要的因素。他們接收,轉(zhuǎn)換和發(fā)送電能。根據(jù)能源和需求,變電站分為中央配電變電站電壓為110-500kV;主要降壓變電所電壓為110-220/6-10-35kV; 深入口變電站為110-330/6-10kV;二次變電站的電壓為6-10Kv;車間變電所電壓為

43、6-10/0.38-0.66kV。在主要的降壓變電所,電源能量轉(zhuǎn)化電壓為110-220kV,通常使用6-10Kv(有時(shí)為35kV變電所)的電壓分配給企業(yè)和被用來滿足高壓服務(wù)。</p><p>  中央配電變電站從電力系統(tǒng)接收能量并分發(fā)它(不包括或者包括部分變換) 給企業(yè)不同區(qū)域,通過空中電纜和地下電纜線路電壓為110-220kV。 中央分配變電站站不同于主配電變電它是一個(gè)更強(qiáng)大的電力設(shè)施,它的電壓大部分在110-

44、220kV的電壓。它可以簡化初級(jí)電壓、中級(jí)電壓或地區(qū)的開關(guān)電路。中低級(jí)別變電站改造能量來自6-10kv的電壓,它的二次側(cè)電壓為380/220或660/380。</p><p>  升壓變壓器變電站用于將電廠產(chǎn)生的能量轉(zhuǎn)化使發(fā)電機(jī)產(chǎn)生的電壓升高,從而有效地減少在遠(yuǎn)距離輸電能量的損失轉(zhuǎn)換器變電站的目的是為了將直流轉(zhuǎn)換成交流(有時(shí)相反)和轉(zhuǎn)換成能量時(shí)改變頻率。轉(zhuǎn)換器變電站的能量轉(zhuǎn)換是用半導(dǎo)體整流器來變頻的。帶半導(dǎo)體整流

45、器的轉(zhuǎn)化器變電站是最經(jīng)濟(jì)的。6-10kV的配電變電站主要依據(jù)主配電變電站(有時(shí)依據(jù)中央配電變電站)。110-220kV變電站系統(tǒng)區(qū)域的劃分時(shí),根據(jù)變電站設(shè)備功能劃分時(shí)是有學(xué)問的,6-10kV的變電站設(shè)備劃分在變電站的入口。</p><p>  根據(jù)變電站變的位置,電站設(shè)備在可以露天或室內(nèi)。6-10kV變電站的在電纜的類型主要是供給輸出線。在35-220kV變電站空中線路樣式,在變電站架線和接線,主要注重供電生產(chǎn)的

46、可靠和經(jīng)濟(jì)。</p><p>  用工業(yè)的方式建設(shè)變電站,是使用大量的數(shù)塊和在電氣工程組織和工廠電氣工程等行業(yè)的車間的位置進(jìn)行組裝。變電站通常是專為不連續(xù)操作的責(zé)任人員所設(shè)計(jì),但用的是基本的自動(dòng)設(shè)備和信號(hào)裝置。</p><p>  當(dāng)建立變電站結(jié)構(gòu)的一部分,應(yīng)當(dāng)采用薄型建造結(jié)構(gòu)以及由彎段組成的組件(板材、地板等)。這些元件是預(yù)先安裝區(qū)外面建造區(qū)域并且只是在這個(gè)位置組裝。這樣可以有效的削減變

47、電所建造成本。</p><p>  變電站基本電路概念設(shè)計(jì)的選擇,是根據(jù)企業(yè)的供電系統(tǒng)特點(diǎn)得到的。變電站電壓特性主要入口,變壓器和輸出電纜線路導(dǎo)線或當(dāng)前導(dǎo)體的二次電壓.變電站安裝的設(shè)備和元件,設(shè)備和元件的若干種可能的組合是非常好的。當(dāng)闡述了變電站的電路時(shí)爭取切換裝置最大的簡化和數(shù)目的最小化。這樣的變電站更可靠、經(jīng)濟(jì)。電路簡化是采用自動(dòng)接入或自動(dòng)轉(zhuǎn)入儲(chǔ)備的方法,允許快速和無錯(cuò)誤的自動(dòng)接入每一個(gè)元件和使用設(shè)備。<

48、;/p><p>  當(dāng)設(shè)計(jì)工業(yè)企業(yè)全電壓變電站時(shí),下面的基本因素都要考慮在內(nèi)。</p><p>  1.優(yōu)先使用采用兩編組的單總線系統(tǒng)可以確??煽康暮徒?jīng)濟(jì)的供應(yīng)電力。</p><p>  2.配套建設(shè)和變電站廣泛使用。</p><p>  3.變電站使用自動(dòng)化并且支持遙測技術(shù);如果變電站的設(shè)計(jì)并不支持使用自動(dòng)化或遙測、線路安而且不允許添加設(shè)備,確

49、保以后沒有過度投資和返工。</p><p>  4.使用簡單、便宜的裝置,有絕緣裝置的斷路器、短路開關(guān)、過載保護(hù)隔離器、保險(xiǎn)絲,預(yù)期到他們的交換容量可考慮大幅度削減昂貴的器件需要和臨界油、真空、螺線管和空氣開關(guān)電路使用。變電站和開關(guān)電路,采用這樣的設(shè)備的每個(gè)生產(chǎn)線服從個(gè)體變壓器、裝配、允許他們同時(shí)的斷開而不破壞斷開連接的生產(chǎn)流程的機(jī)制的線條。</p><p>  變電站的線路的意義,最重要

50、的一點(diǎn)是要妥善安排與選擇轉(zhuǎn)換器件(開關(guān)、隔離者、電流限制器等、避雷器、高低壓熔斷器),這決定了變電站的目的、功能和意義。</p><p>  很多年以前,科學(xué)家們對(duì)電仍只有很模糊的概念。他們之中不少人認(rèn)為電是一種“流體”,這種流體就像水流經(jīng)管道一樣流過導(dǎo)線。但他們并不了解是什么東西使電流動(dòng)。他們之中的許多人覺得電是有某種極小的微粒構(gòu)成的,但試圖把電分離成單個(gè)的小顆粒他們卻束手無策。</p><

51、p>  此后,以為偉大的美國科學(xué)家密利坎于1909年,真正地稱出了單個(gè)的電粒子的重量并算出它的電荷而使科學(xué)界震驚不已。這可能是人類做過的最細(xì)致的計(jì)量工作之一,因?yàn)橐粋€(gè)單個(gè)的電粒子的重量僅為一磅的百萬分之一,百萬分之一的一半左右的重量。要合成一磅重需要的電粒子數(shù)將要比大西洋的全部水的水滴數(shù)還要多。</p><p>  這些電粒子,他們對(duì)我們并不陌生,因?yàn)槲覀冎浪麄兙褪请娮?。?dāng)大量電子擺脫原子跑出來并通過導(dǎo)線

52、運(yùn)動(dòng)時(shí),我們把這種現(xiàn)象說成是電通過導(dǎo)線“流動(dòng)”。是的,早先的科學(xué)家所說的電的“流體”只不過是沿著導(dǎo)線流動(dòng)的電子。</p><p>  那么,如何能使一些單個(gè)的電子擺脫原子的束縛而跑出來呢?</p><p>  而且,又怎樣能使這些自由電子沿導(dǎo)線運(yùn)動(dòng)呢?</p><p>  第一個(gè)問題的答案就在于原子本身的結(jié)構(gòu)上。某些原子的結(jié)構(gòu)使他們很容易失去電子。例如,一個(gè)銅原子在

53、正常情況下有29個(gè)電子,它們排列在核子周圍的4個(gè)不同的軌道上。最里層的軌道上有2個(gè)電子。第二層較大的軌道上有8個(gè)電子。第三層軌道上擠滿18個(gè)電子。而外層軌道上只有一個(gè)電子。正是這個(gè)外層電子,銅原子不斷丟掉它,因?yàn)檫@個(gè)電子受原子的約束不那么緊。它忽而游離而去,并被另一游離的電子所替代,然后,這后一個(gè)電子也游離而去。</p><p>  結(jié)果,在銅導(dǎo)線中自由電子在銅原子之間向四面八方漂浮。所以,盡管對(duì)你們的普通的肉眼

54、來說,銅導(dǎo)線看來是完全不動(dòng)的,但在它內(nèi)部卻不斷地進(jìn)行著大量的活動(dòng)。</p><p>  如果導(dǎo)線把電輸送到一盞電燈或者另外某個(gè)電氣設(shè)備那里,這些電子就不會(huì)雜亂無章地到處跑來跑去,而是它們中的許多電子將會(huì)向一個(gè)方向奔去-從導(dǎo)線的一端奔向另一端。</p><p>  這就把我們引向第二個(gè)問題,如何才能使自由電子沿導(dǎo)線運(yùn)動(dòng)呢?好啦,人們已經(jīng)找到幾種方法來做到這一點(diǎn)。一種就是化學(xué)方法。伏特電堆,或

55、者叫電池,就是能使電流在導(dǎo)線中流動(dòng)的一種化學(xué)裝置。另一種方法就是電磁法。法拉第和亨利發(fā)現(xiàn)了怎樣能把磁鐵用來使電在導(dǎo)線中流動(dòng)的辦法。</p><p><b>  磁鐵</b></p><p>  幾乎每個(gè)人都見過馬蹄形磁鐵-之所以這樣叫他是因?yàn)樗麄兊男螤钭龀神R蹄形的??赡苣銈兌加么盆F做過試驗(yàn),并且看到它是怎樣吸起按釘,小釘子或者其他一些小鐵件的。人們了解磁鐵已經(jīng)幾千年了

56、。</p><p>  據(jù)傳說,幾千年前有個(gè)名叫麥格尼斯的牧羊人住在地中海的克里特島上。他有一根牧羊人用的帶鐵頭的棍杖。一天,他發(fā)現(xiàn)一塊奇形怪狀的黑石頭黏在鐵頭上。后來,當(dāng)又發(fā)現(xiàn)許多這種石頭時(shí),人們就叫它們?yōu)榇盆F。這些就是天然磁鐵。</p><p>  近年來,人們已經(jīng)掌握怎樣使用鐵來制成磁鐵。尤其重要的是,人們發(fā)現(xiàn)了如何使用磁鐵推動(dòng)電子通過導(dǎo)線-也就是怎樣使電流動(dòng)。</p>

57、<p>  在我們討論這點(diǎn)之前,磁鐵有某些特性我們應(yīng)當(dāng)了解。如果把一塊玻璃放在馬蹄形磁鐵的端部,然后把一些鐵粉末撒在玻璃上,那么鐵粉自己就會(huì)排成許多線。如果用一根棒做的話,就更容易看出這些鐵粉排成的線條了。這些實(shí)驗(yàn)演示了科學(xué)家們所謂的磁力線。他們解釋說。磁鐵通過磁鐵兩端之間延伸出來的磁力線起作用。</p><p>  但是,在電子周圍似乎也有磁力線。把一根導(dǎo)線穿過一塊硬紙板,在紙板上撒上鐵粉,并把電池

58、與導(dǎo)線連通在一起,這點(diǎn)就可以得到證明。由于運(yùn)動(dòng)的電子的磁性的結(jié)果,鐵粉就會(huì)繞導(dǎo)線周圍形成一些圓環(huán)。因此,我們可以看到,在運(yùn)動(dòng)者的電子和磁性之間有一種關(guān)系。磁性就是由電子的運(yùn)動(dòng)引起的。</p><p>  當(dāng)然,電子并不是在磁棒里真的“流動(dòng)”,但它們卻是在運(yùn)動(dòng),在繞鐵原子核做旋轉(zhuǎn)運(yùn)動(dòng)。然而,在磁鐵中,原子都排列的使它們的電子都向同一方向旋轉(zhuǎn)。也許可打一個(gè)恰當(dāng)?shù)谋扔鳎拖裨S多小孩在他們頭頂上以順時(shí)針方向甩動(dòng)系在線上的

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