【正文】 在一個(gè)降壓變壓器中傳輸變比a遠(yuǎn)大于1(a)，同樣的，一個(gè)升壓變壓器的變比小于1(a)。 終端電壓的比率變化有些根據(jù)負(fù)載和它的功率因素。因此Pm = Pout或者VpIp primary PF = VsIs secondary PF這里PF代表功率因素。因此Ep = 并且Es = 其中Np和Es是一次側(cè)繞組和二次側(cè)繞組的匝數(shù)。原邊的電壓和它產(chǎn)生的磁通波形是正弦形的；因此產(chǎn)生電動(dòng)勢(shì)Ep和Es的值是做正弦變化的。的相位差。因?yàn)橐淮蝹?cè)繞組中的磁通會(huì)通過(guò)二次繞組，依據(jù)法拉第電磁感應(yīng)定律，二次側(cè)繞組中將產(chǎn)生一個(gè)電動(dòng)勢(shì)E，即E=NΔφ/Δt。這個(gè)電流分量向鐵芯提供用于損耗的電流。因?yàn)樵诳蛰d時(shí)，原邊繞組中的鐵芯相當(dāng)于一個(gè)很大的電抗，空載電流的相位大約將滯后于原邊電壓相位90186。外加電壓在一次側(cè)繞組中產(chǎn)生一個(gè)小電流Iθ。磁通是變化的；因此依據(jù)楞次定律，電磁感應(yīng)在二次側(cè)產(chǎn)生了電壓。典型的效率范圍在92到99%，上限值適用于大功率變壓器。2. 雙繞組變壓器變壓器的最簡(jiǎn)單形式包括兩個(gè)磁通相互耦合的固定線圈。 it is called the primary leakage flux. The secondary leakage flux gives rise to an induced voltage that is not counter balanced by an equivalent induced voltage in the primary. Similarly, the voltage induced in the primary is not counterbalanced in the secondary winding. Consequently, these two induced voltages behave like voltage drops, generally called leakage reactance voltage drops. Furthermore, each winding has some resistance, which produces a resistive voltage drop. When taken into account, these additional voltage drops would plete the equivalent circuit diagram of a practical transformer. Note that the magnetizing branch is shown in this circuit, which for our purposes will be disregarded. This follows our earlier assumption that the noload current is assumed negligible in our calculations. This is further justified in that it is rarely necessary to predict transformer performance to such accuracies. Since the voltage drops are all directly proportional to the load current, it means that at noload conditions there will be no voltage drops in either winding.2譯文變壓器1. 介紹要從遠(yuǎn)端發(fā)電廠送出電能，必須應(yīng)用高壓輸電。 thusE = Since the same flux links with the primary and secondary windings, the voltage per turn in each winding is the same. HenceEp = andEs = where Ep and Es are the number of turn on the primary and secondary windings, respectively. The ratio of primary to secondary induced voltage is called the transformation ratio. Denoting this ratio by a, it is seen thata = = Assume that the output power of a transformer equals its input power, not a bad sumption in practice considering the high efficiencies. What we really are saying is that we are dealing with an ideal transformer。 φ is therefore in phase with Im.The second ponent, Ie=I0sinθ0, is in phase with the primary voltage. It is the current ponent that supplies the core losses. The phasor sum of these two ponents represents the noload current, orI0 = Im+ IeIt should be noted that the noload current is distortes and nonsinusoidal. This is the result of the nonlinear behavior of the core material.If it is assumed that there are no other losses in the transformer, the induced voltage In the primary, Ep and that in the secondary, Es can be shown. Since the magnetic flux set up by the primary winding，there will be an induced EMF E in the secondary winding in accordance with Faraday’s law, namely, E=NΔφ/Δt. This same flux also links the primary itself, inducing in it an EMF, Ep. As discussed earlier, the induced voltage must lag the flux by 90186。 therefore, it induces a voltage in the secondary by electromagnetic induction in accordance with Lenz’s law. Thus the primary receives its power from the source while the secondary supplies this power to the load. This action is known as transformer action.3. TRANSFORMER PRINCIPLESWhen a sinusoidal voltage Vp is applied to the primary with the secondary opencircuited, there will be no energy transfer. The impressed voltage causes a small current Iθ to flow in the primary winding. This noload current has two functions: (1) it produces the magnetic flux in the core, which varies sinusoidally between zero and φm, where φm is the maximum value of the core flux。我們共同討論，一起攻克了許多難題。致謝一個(gè)學(xué)期的畢業(yè)設(shè)計(jì)很多結(jié)束了，經(jīng)過(guò)多次的修改，補(bǔ)充，增刪，現(xiàn)在已基本成稿。無(wú)論是對(duì)思考問(wèn)題的方式，還是對(duì)知識(shí)掌握的程度都有很大的提高，給我在今后的工作中奠定了堅(jiān)實(shí)的基礎(chǔ)。千萬(wàn)不要?jiǎng)h除行尾的分節(jié)符，此行不會(huì)被打印。則單位長(zhǎng)度母線的質(zhì)量為：導(dǎo)體斷面二次矩為：當(dāng)導(dǎo)體安裝方式為兩端固定時(shí)，跨數(shù)大于3，由《供用電工程》276頁(yè)，表94查得頻率系數(shù)。母線最大相間計(jì)算應(yīng)力為： （724）W母線對(duì)垂直于作用力方向軸的截面系數(shù)（也稱抗彎矩）。”若固有頻率在上述范圍之外，可取β=1。本設(shè)計(jì)取絕緣子的跨距為開(kāi)關(guān)柜的寬度：L=。熱穩(wěn)定校驗(yàn)合格。”按最大長(zhǎng)期工作電流選擇匯流母線 查《電力工程電氣設(shè)計(jì)手冊(cè)》340頁(yè)，表82，選用矩形鋁母線，水平放置。矩形導(dǎo)體的散熱和機(jī)械強(qiáng)度與母線的布置方式有關(guān)。本設(shè)計(jì)初選六種開(kāi)關(guān)柜，分別為變壓器10KV側(cè)出線回路柜、分段母聯(lián)回路柜、架空出線柜、所用變壓器柜、電壓互感器及避雷器柜、補(bǔ)償電容器柜。根據(jù)開(kāi)關(guān)柜數(shù)量的多少和可靠性的要求，確定使用固定式還是手車式開(kāi)關(guān)柜。本設(shè)計(jì)變電所60KV側(cè)避雷器選用FZ—60型，10KV側(cè)選用FS—10型避雷器。故所選用的兩種電流互感器滿足要求。選用型電流互感器用于不同的饋出線上，其額定電流比為。其技術(shù)數(shù)據(jù)如下表所示：表710 LCWD60型電流互感器參數(shù)型號(hào)次級(jí)組合額定變流比準(zhǔn)確級(jí)次10%倍數(shù)二次負(fù)荷1S熱穩(wěn)定倍數(shù)動(dòng)穩(wěn)定倍數(shù)二次負(fù)荷Ω倍數(shù)13LCWD60D/1(300～600)/5D30751501154（2）動(dòng)穩(wěn)定校驗(yàn) 動(dòng)穩(wěn)定校驗(yàn)合格。）電壓互感器型號(hào)如下：JCC560型電壓互感器： JSJB10型電壓互感器： J電壓互感器； J電壓互感器；C串級(jí)絕緣形式； S三相 C—瓷箱式； J油浸式；5—設(shè)計(jì)序號(hào)； B帶補(bǔ)償繞組；60額定電壓（kV）。此種接線不能用于供電絕緣檢查電壓表，不允許將電壓互感器高壓側(cè)中性點(diǎn)接地。根據(jù)《電力工程電氣設(shè)計(jì)手冊(cè)》P250型式選擇規(guī)定：6～20KV配電裝置一般采用油浸絕緣結(jié)構(gòu)。在配電裝置中，主要用來(lái)在檢修設(shè)備時(shí)形成可見(jiàn)的空氣絕緣間隔。 10KV側(cè)斷路器選擇(1)10kV進(jìn)線斷路器和母聯(lián)斷路器選擇高壓斷路器的最大長(zhǎng)期工作電流: 查《高壓電器》P306頁(yè),，三臺(tái)均選型斷路器，其技術(shù)數(shù)據(jù)如下表：表73 斷路器參數(shù)表型號(hào)UN kVIN （A）開(kāi)斷電流（kA）開(kāi)斷容量(MVA)極限通過(guò)電流峰值（kA）動(dòng)穩(wěn)定電流（kA）熱穩(wěn)定電流（4S）（kA）固有分閘時(shí)間（S）合閘時(shí)間（S）10100020300505020≤≤短路時(shí)間，導(dǎo)體的發(fā)熱主要由短路電流的周期分量來(lái)決定，可以不計(jì)非周期分量的影響。 60KV側(cè)斷路器的選擇主接線采用內(nèi)橋接線，變壓器一次側(cè)斷路器的最大長(zhǎng)期工作電流為： 查《電力工程電氣設(shè)備手冊(cè)》621頁(yè)，表413，選擇3臺(tái)型斷路器。 斷路器的選擇在各種電壓等級(jí)變電所的設(shè)計(jì)中，斷路器是最為重要的電氣設(shè)備，它是通斷故障電流和正常負(fù)荷電流的元件。所以通過(guò)計(jì)算機(jī)軟件計(jì)算得出：；；。電力網(wǎng)在設(shè)計(jì)及運(yùn)行時(shí)考慮最嚴(yán)重的故障情況下工作的可能性時(shí)，三相短路起著決定性的作用。在三相系統(tǒng)中短路的基本形式有：三相短路K（3）；兩相短路K（2）；單相接地短路K（1）；以及兩相接地短路K（1，1）。再其次是人員過(guò)失，例如運(yùn)行人員帶負(fù)荷拉刀閘，檢修線路或設(shè)備之后未拆除接地線就合閘供電等?？紤]綜合因素選第一方案為本變電所的主接線方案。由于第二種方案比第一種方案所占的面積大、設(shè)備多、故不經(jīng)濟(jì)。由于變壓器是少故障元件，一般不經(jīng)常切換。 圖51高壓側(cè)采用內(nèi)橋接線，低壓側(cè)采用單母線分段的主接線圖52 高壓側(cè)采用單母線分段，低壓側(cè)采用單母線分段的主接線以上兩個(gè)方案中，主接線二次側(cè)方案相同，只比較一次側(cè)方案。變電所的主接線是電力系統(tǒng)接線組成中的一個(gè)重要部分。其技術(shù)參數(shù)如下表所示：表41 BWF2001W電容器的技術(shù)參數(shù)型號(hào)規(guī)格額定電壓（kV）標(biāo)稱容量（KVar）標(biāo)稱電容μF相數(shù)外形尺寸長(zhǎng)*寬*高（mm）重量kgBWF—200—1W2001700*174*1010120則所需電容器臺(tái)數(shù)為：臺(tái)式中 計(jì)算補(bǔ)償容量（KVar）； 每臺(tái)電容器的標(biāo)稱容量（KVar）。所以本次設(shè)計(jì)采用星形接線方式，被選