變電所畢業(yè)設(shè)計(jì)外文翻譯-其他專業(yè)(完整版)
【正文】 （ 1）在鐵芯中產(chǎn)生電磁通，該磁通在零和 ? φm 之間做正弦變化， φm 是鐵芯磁通的最大值；（ 2）它的一個(gè)分量說明了鐵芯中的渦流和磁滯損耗。 從交流電源流入電流的一側(cè)被稱為變壓器的一次側(cè)繞組或者是原邊。因?yàn)樽罱K的負(fù)荷，在一些點(diǎn)高電壓必須降低。 在電力應(yīng)用中，使用層式鐵芯變壓器 (本文中提到的 )。這就是變壓器的作用。就是這個(gè)分量在鐵芯中建立了磁通；因此磁通 φ 與 Im同相。正如前文中討論到的，所產(chǎn)生的電壓必定 滯后于磁通 90186。它遵循 Eavg = N 21/(2 )mf? = 4fNφm 其中 N 是 指線圈的匝數(shù)。匝數(shù)比可以衡量二次側(cè)電壓相對(duì)于一次惻電壓是升高或者是降低。這是一種特殊類型的變壓器，可被應(yīng)用于當(dāng)一次側(cè)和二次側(cè)需要相互絕緣以維持相同的電壓等級(jí)的狀況下。這個(gè)公式應(yīng)用于變壓器的阻抗匹配。這個(gè)磁通的方向在任何一個(gè)時(shí)刻都和主磁通反向。其需要的條件是 E 降落很多來使電流 Ip 增加。 當(dāng)一個(gè)電流流過二次側(cè)繞組，它的磁動(dòng)勢(shì)（ NsIs）將產(chǎn)生一個(gè)磁通，于空載電流 I0產(chǎn)生的磁通 φ0不同，它只停留在二次側(cè)繞組中。由于分支勵(lì)磁體現(xiàn)在電流里，為了分析我們可以將它忽略。 in phase behind the primary voltage VP. It is this ponent that sets up the flux in the core。 the marked terminals have the same polarity. Thus when a load is connected to the secondary, the instantaneous load current is in the direction shown. In other words, the polarity markings signify that when positive current enters both windings at the marked terminals, the MMFs of the two windings add. Since the secondary voltage depends on the core flux φ0, it must be clear that the flux should not change appreciably if Es is to remain essentially constant under normal loading conditions. With the load connected, a current Is will flow in the secondary circuit, because the induced EMF Es will act as a voltage source. The secondary current produces an MMF NsIs that creates a flux. This flux has such a direction that at any instant in time it opposes the main flux that created it in the first place. Of course, this is Lenz’s law in action. Thus the MMF represented by NsIs tends to reduce the core flux φ0. This means that the flux linking the primary winding reduces and consequently the primary induced voltage Ep, This reduction in induced voltage causes a greater difference between the impressed voltage and the counter induced EMF, thereby 9 allowing more current to flow in the primary. The fact that primary current Ip increases means that the two conditions stated earlier are fulfilled: (1) the power input increases to match the power output, and (2) the primary MMF increases to offset the tendency of the secondary MMF to reduce the flux. In general, it will be found that the transformer reacts almost instantaneously to keep the resultant core flux essentially constant. Moreover, the core flux φ0 drops very slightly between n o load and full load (about 1 to 3%), a necessary condition if Ep is to fall sufficiently to allow an increase in Ip. On the primary side, Ip’ is the current that flows in the primary to balance the demagizing effect of Is. Its MMF NpIp’ sets up a flux linking the primary only. Since the core flux φ0 remains constant. I0 must be the same current that energizes the transformer at no load. The primary current Ip is therefore the sum of the current Ip’ and I0. Because the noload current is relatively small, it is correct to assume that the primary ampereturns equal the secondary ampereturns, since it is under this condition that the core flux is essentially constant. Thus we will assume that I0 is negligible, as it is only a small ponent of the fullload current. When a current flows in the secondary winding, the resulting
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