變電所畢業(yè)設(shè)計(jì)外文翻譯-wenkub.com
2025-06-23 11:35 本頁(yè)面
【正文】 這證明了它對(duì)我們分析變壓器時(shí)所產(chǎn)生的影響微乎其微。另外，兩側(cè)繞組同樣具有阻抗，這也將產(chǎn)生一個(gè)電阻壓降。另外，流過一次側(cè)繞組的負(fù)載電流只在一次側(cè)繞組中產(chǎn)生磁通，這個(gè)磁通被稱為一次側(cè)的漏磁。因?yàn)樵谶@種狀況下鐵芯的磁通是恒定的。它的磁動(dòng)勢(shì)NpIp’只停留在一次側(cè)?？偟膩碚f，變壓器為了保持磁通是常數(shù)，對(duì)磁通變化的響應(yīng)是瞬時(shí)的。因此，NsIs所產(chǎn)生的磁動(dòng)勢(shì)會(huì)使主磁通φ0減小。當(dāng)變壓器帶負(fù)荷運(yùn)行時(shí)，將有電流Is流過二次側(cè)，因?yàn)镋s產(chǎn)生的感應(yīng)電動(dòng)勢(shì)相當(dāng)于一個(gè)電壓源。如果點(diǎn)號(hào)同在線圈的上端，就意味著它們的極性相同。根據(jù)Vs和Is，可得Vp和Ip的比例是 = = 但是Vs / Is 負(fù)荷阻抗ZL，因此我們可以這樣表示Zm (primary) = a2ZL這個(gè)等式表明二次側(cè)連接的阻抗折算到電源側(cè)，其值為原來的a2倍。顯然，鐵芯中的電磁通形成了連接原邊和副邊的回路。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.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 th
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