The fundamental use of a transformer is stepping voltage up or down from the powered coil to the unpowered coil. This provides AC an advantaged well above DC in the realm of power distribution because, as mentioned above, transmitting electrical power over long distances is a lot more efficient with higher, stepped-up voltages and smaller, stepped-down currents. Before reaching power outlets, voltage is stepped back down and current is stepped back up.
This type of transformer technology has made long-range electric power distribution efficient and practical. Without transformers, it would be far too costly to construct power systems in their current long-distance form. And, because mutual inductance relies on changing magnetic fields, transformers only work with AC. Have you enjoyed reading this article? Then follow us on LinkedIn and stay up-to-date with daily posts about the latest developments on the industry, products and applications, tools and software as well as research and development.
Infineon Technologies AG. Maschinenfabrik Reinhausen GmbH. Rogers Germany GmbH. A turning point in the battle came when George Westinghouse, a famous industrialist from Pittsburgh, purchased Nikola Tesla's patents for AC motors and transmission the next year.
Thomas Edison Image courtesy of biography. In the late s, DC could not be easily converted to high voltages. As a result, Edison proposed a system of small, local power plants that would power individual neighborhoods or city sections.
Even though the voltage drop across the power lines was accounted for, power plants needed to be located within 1 mile of the end user. This limitation made power distribution in rural areas extremely difficult, if not impossible.
With Tesla's patents, Westinghouse worked to perfect the AC distribution system. Transformers provided an inexpensive method to step up the voltage of AC to several thousand volts and back down to usable levels. At higher voltages, the same power could be transmitted at much lower current, which meant less power lost due to resistance in the wires. As a result, large power plants could be located many miles away and service a greater number of people and buildings.
Over the next few years, Edison ran a campaign to highly discourage the use of AC in the United States, which included lobbying state legislatures and spreading disinformation about AC.
Edison also directed several technicians to publicly electrocute animals with AC in an attempt to show that AC was more dangerous than DC. In attempt to display these dangers, Harold P. In , the International Electro-Technical Exhibition was held in Frankfurt, Germany and displayed the first long distance transmission of three-phase AC, which powered lights and motors at the exhibition. Several representatives from what would become General Electric were present and were subsequently impressed by the display.
The following year, General Electric formed and began to invest in AC technology. Westinghouse won a contract in to build a hydroelectric dam to harness the power of Niagara falls and transmit AC to Buffalo, NY. The project was completed on November 16, and AC power began to power industries in Buffalo. This milestone marked the decline of DC in the United States. However, due to the high cost and maintenance of the Thury systems, HVDC was never adopted for almost a century.
With the invention of semiconductor electronics in the s, economically transforming between AC and DC became possible.
Specialized equipment could be used to generate high voltage DC power some reaching kV. In the end, Edison, Tesla, and Westinghouse may have their wishes come true.
AC and DC can coexist and each serve a purpose. You should now have a good understanding of the differences between AC and DC. AC is easier to transform between voltage levels, which makes high-voltage transmission more feasible.
DC, on the other hand, is found in almost all electronics. You should know that the two do not mix very well, and you will need to transform AC to DC if you wish to plug in most electronics into a wall outlet. With this understanding, you should be ready to tackle some more complex circuitry and concepts, even if they contain AC. Take a look at the following tutorials when you are ready to dive deeper into the world of electronics:.
See our Engineering Essentials page for a full list of cornerstone topics surrounding electrical engineering. Take me there! Need Help? Moreover, the power is transmitted at much higher voltages than the V AC V in most parts of the world we use in homes and on the job.
Economies of scale make it cheaper to build a few very large electric power-generation plants than to build numerous small ones. This necessitates sending power long distances, and it is obviously important that energy losses en route be minimized. High voltages can be transmitted with much smaller power losses than low voltages, as we shall see.
See Figure 4. For safety reasons, the voltage at the user is reduced to familiar values. The crucial factor is that it is much easier to increase and decrease AC voltages than DC, so AC is used in most large power distribution systems.
Figure 4. Power is distributed over large distances at high voltage to reduce power loss in the transmission lines. The voltages generated at the power plant are stepped up by passive devices called transformers see Transformers to , volts or more in some places worldwide.
At the point of use, the transformers reduce the voltage transmitted for safe residential and commercial use. This gives. One-fourth of a percent is an acceptable loss. Note that if MW of power had been transmitted at 25 kV, then a current of A would have been needed.
This would result in a power loss in the lines of The lower the voltage, the more current is needed, and the greater the power loss in the fixed-resistance transmission lines.
Of course, lower-resistance lines can be built, but this requires larger and more expensive wires. If superconducting lines could be economically produced, there would be no loss in the transmission lines at all.
But, as we shall see in a later chapter, there is a limit to current in superconductors, too. In short, high voltages are more economical for transmitting power, and AC voltage is much easier to raise and lower, so that AC is used in most large-scale power distribution systems.
It is widely recognized that high voltages pose greater hazards than low voltages. But, in fact, some high voltages, such as those associated with common static electricity, can be harmless.
So it is not voltage alone that determines a hazard. It is not so widely recognized that AC shocks are often more harmful than similar DC shocks. There were bitter fights, in particular between Edison and George Westinghouse and Nikola Tesla, who were advocating the use of AC in early power-distribution systems.
Sign up for our Newsletter! Mobile Newsletter banner close. Mobile Newsletter chat close. Mobile Newsletter chat dots. Mobile Newsletter chat avatar. Mobile Newsletter chat subscribe. Prev NEXT. Physical Science.
0コメント