外文翻譯--變壓器的類型及結(jié)構(gòu)-wenkub
2023-05-19 07:43:33 本頁面
【正文】 imary and secondary windings in a physical transformer are wrapped one on top of the other with the lowvoltage winding innermost． Such an arrangement serves two purposes： simplifies the problem of insulating the highvoltage winding from the core． results in much less leakage flux than would be the two windings were separated by a distance on the core． Power transformers are given a variety of different names, depending on their use in power systems. A transformer connected to the output of a generator and used to step its vo1tage up to transmission levels is sometimes called a unit transformer． The transformer at the other end of the transmission line， which steps the voltage down 2 from transmission levels to distribution levels is called a substation transformer. Finally， the transformer that takes the distribution voltage and steps it down to the final vo1tage at which the power is actually used is called a distribution transformer． A11 these devices are essentially the same the only difference among them is their intended use． In addition to the various power transformers， two specialpurpose transformers are used with electric machinery and power systems． The first of these special transformers is a device specially designed to sample a high vo1tage and produce a low secondary vo1tage directly proportional to it. Such a transformer is called a potential transformer． A power transformer also produces a secondary vo1tage directly proportional to its primary voltage。與電源連接的繞組稱為一次繞組或輸入繞組。一類是由繞組纏繞在一個簡單的矩形鋼片疊 成的鐵芯兩邊 而構(gòu)成。鐵芯不論是芯式還是框式，都是由薄 薄的鐵芯片做成的。 在電力系統(tǒng)中，根據(jù)不同的用途，電力變壓器有許多種不同的名 稱。以上變壓器的結(jié)構(gòu)基本相同，唯一的區(qū)別在于各自的實際用途不同。功率變壓器中產(chǎn)生的二次側(cè)的電壓也與一次側(cè)的電壓成正比。 方向保護(hù)基礎(chǔ) 早期，對于遠(yuǎn)離發(fā)電站的用戶，為改善其供電可靠性提出了雙回線供電的設(shè)想。當(dāng)發(fā)生故障時，只斷開故障線 。可以考慮在四個斷路器上裝設(shè)瞬時和延時起動繼電器。 6 無論故障點靠近斷路器 B 或 D 的哪一端，流過斷路器 B 和 D 的故障電流大小是相同的。對于斷路器 D，電流通過斷路器流向負(fù)載母線。斷路器 A 和 C 裝設(shè)無方向的過流延時繼電器及瞬時動作的電流繼電器。于是快速保護(hù)可以保護(hù)發(fā)電機和負(fù)載之間線路長度的大部分。圖 1— 1 所示系統(tǒng)的參考矢量可從負(fù)載母線電壓矢量推出。目前正在進(jìn)行更短時間的采樣的研究工作。 。由于要在電力系統(tǒng)電磁暫態(tài)過程中預(yù)測，這項工作比較復(fù)雜。因此，電壓、電流失量必須在A C B D G 負(fù)載 7 一個時間間隔內(nèi)采樣。這就是我們所說的順序跳閘，通常在上述情況下這樣做是允許的。 A 和 C 的延
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