外文翻譯---發(fā)電機(jī)和變壓器(存儲版)
【正文】 而產(chǎn)生的熱損耗。流電流在鐵芯中旋轉(zhuǎn)，產(chǎn)生感應(yīng)現(xiàn)象，因為鐵芯畢竟是變化磁場的導(dǎo)體。變壓器效率很高，損耗統(tǒng)常低于3%,因此這使我們假定它在計算時是無損耗的。鐵芯主要有兩種型式：。大概只有發(fā)電廠才能見到升壓變壓器。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。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。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。 變壓器是通過磁場作用將交流電從某一電壓等級轉(zhuǎn)換至另一電壓等級的設(shè)備。 most have two although they may have many more.The usual purpose of transformers is to change the level of voltage. But sometimes they are used to isolate a load from the power source.Standard power transformers have two oils. These coils are labeled PRIMARY and SECONDARY. The primary coil is the one connected to the source. The secondary is the one connected to the load .There is no electrical connection between the primary and secondary. The secondary gets its voltage by induction.The only place where you will see a STEPUP transformer is at the generating station. Typically, electricity is generated at 13,800 volts. It is stepped up to 345,000 volts for transmission. The next stop is the substation where it is stepped down to distribution levels, around 15,000 volts. Large substation transformers have cooling fins to keep them from overheating. Other transformers are located near points where the electric power is used.The coils of transformer are electrically are electrically insulated from each other. There is a magnetic link, however. The two coils are wound on the same core. Current in the primary magnetizes the core. This produces a magnetic field in the core. The core field then affects current in both primary and secondary.There are two main designs for cores: CORE type has the core inside the windings. SHELL type has the core outside.Smaller power transformers are usually of the core type. The very large transformers are of the shell type. There is no different in their operation, however.Coils are wound with copper wire. The resistance is kept as low as possible to keep losses low.Transformers are very efficient. The losses are often less than 3 percent. This allows us to assume that they are perfect in many putations.Perfect means that the wire has no resistance. It also means that there are no power losses in the core.Further, we assume that there is no flux leakAge. That is, all of the magnetic flux links all of the turns on each coil.To g
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