外文翻譯---發(fā)電機(jī)和變壓器-展示頁(yè)
2025-01-26 23:07本頁(yè)面
【正文】 reduce eddy currents to a minimn.The primary and secondary windings in a physical transformer are wrapped one on top of the other with lowvoltage winding innermost. Such an arrangement serves two purpose: (1)It simplifies the problem of insulating the highvoltage winding from the core. (2)It 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 there use in power systems. A transformer connected to the output of a generator and used to step its voltage to transmission levels is sometimes called a unit transformer. The transformer at the other end of the transmission line, which steps the voltage down from transmission levels, is called a substation transformer. Finally, the transformer that takes his distribution levels, is called a distribution transformer. All these devices are essentially the samethe only difference among them is their intended use.In addition to the various power transformer, twospecial purpose transformers are used with electric machinery and power systems. The first of these special transformers is a device specially designed to sample a high voltage and produce a low secondary voltage directly proportional to it. Such a transformer is called a potential transformer. A power transformer also produces a secondary voltage directly proportional to its primary voltage。 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 transfo
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