Inventions That Changed the World: War of the Currents
- 2009 23 Sep
In the July/August issue of Home School Enrichment, we did an article entitled "The ‘Shocking' Story of the Battery." A battery is a device that provides electricity in a form called direct current. While batteries are useful for many applications, they have a problem: the direct current they provide cannot be transmitted over long distances (like miles) to provide power to homes and businesses. The invention of alternating current changed that. The way alternating current works makes it very efficient for distribution over power lines.
The World Before Alternating Current
The phenomenon that we know as electricity was first observed about 2750 BC. Ancient Egyptians were familiar with a fish that could shock people. They called it "the Thunderer of the Nile." There are, in fact, a number of fish that can produce electrical shocks, and believe it or not, they were the first electric "devices" people tried to use to alleviate symptoms such as headaches. Sick people were told to touch electric catfish and rays in hopes that the electric jolt would help heal them!
Early scientists, such as Thales, discovered that if a material called amber was rubbed with a piece of cloth, small bits of straw would stick to it. It was as if some mysterious power had been unleashed in the amber. Today, we know that mysterious power as static electricity, and many of us have felt the jolt from a static shock as we walked across carpet.
It took many years, centuries in fact, before scientists began to understand the fundamental properties of electricity, what it was, and how it could be used as a source of energy. In the late 1800s scientists began to invent devices which could actually use electricity to do some useful function, such as the lighbulb, which could supply illumination. But a war was beginning to brew: the War of the Currents.
Static electricity provides a steady stream of particles, called electrons, that move in one direction. The stream of particles, like a stream of water, is called a "current," and the single direction that the electrons flow is called "direct current," or DC. Batteries supply DC. Inventor Thomas Edison was a proponent of using DC to power his inventions.
Other scientists, particularly those in Europe, had found that they could use rotary motion to move magnets to produce oscillating currents. With these currents, the flow of electrons alternated in the direction they moved. This alternating current is known as AC.
In 1882, the first electrical power distribution system was turned on, providing 110 volts DC to some 59 customers located near Thomas Edison's laboratory in lower Manhattan. Engineer, inventor, and entrepreneur George Westinghouse became interested in electricity, but he had some concerns that Edison's DC system was not very efficient. Edison's system used low voltages, but required high currents. This resulted in significant power losses. There was also another serious problem. Different devices, such as lights and motors, required different DC voltages, which meant different electrical lines had to be run to supply the correct voltage level to each piece of equipment.
Westinghouse was aware that a number of Europeans had been experimenting with the novel concept called AC. Alternating current had the advantage that the voltage could be "stepped up" (which means increased) for transmitting over long distances without a power loss, then "stepped down" (which means decreased) so it could be used by consumers. Edison's DC system could not do this.
The Invention of Alternating Current
In 1886, George Westinghouse and some of his colleagues installed the first AC transmission system in Barrington, Massachusetts. A generator produced 500 volts AC and "stepped it up," using a transformer, to 3000 volts AC. The high voltage was transmitted across the power lines and then "stepped down," using another transformer, to 100 volts AC, the voltage used to operate lights.
The transformer was a very crucial piece of equipment that almost never made it to the United States. The earliest practical transformers were invented by a German named Charles Proteus Steinmetz. He worked for the General Electric Company in Schenectady, New York. When he came over from Germany, he was detained at Ellis Island, New York, and was going to be turned away because, at slightly under four feet tall, he was considered medically unfit. A traveling partner convinced the officials that Steinmetz was a mathematical genius who would greatly help the country. He was right! Steinmetz's middle name was appropriate: Proteus was a mythological Greek god who could take on any shape or size. Steinmetz was small in stature but large in ability.
AC power was perfect for operating lights, but what else could it be used for? The answer was electric motors. A Serbian inventor named Nikola Tesla had invented a motor that could run on AC power. Thomas Edison hired Tesla to work on improving machines called DC electrical dynamos. Edison promised to pay him $50,000 for his services, but when it came time to pay up, Edison told Tesla he was just "joking" about the money. Tesla quickly parted ways with Edison and took a job as a laborer digging ditches. The irony was, the ditches he was digging were going to be used by the Edison Electric Company!
When George Westinghouse found out about Tesla, he quickly hired him. Now Tesla was working for the man who was competing head-to-head with Edison in the "current war." Nikola got to work, and by 1888, he introduced the polyphase electrical motor. The polyphase motor ran on electricity from three AC supplies (known as polyphase AC). It may seem a little odd to do this, but Tesla had figured out that using the polyphase AC was a very efficient way to transmit power.
Edison, sensing that Westinghouse was winning the war of currents, tried his best to discredit Westinghouse by saying that AC was too dangerous. To prove his point, he hired an engineer to devise a system that could kill animals using AC. The war was reaching absurd proportions.
The war came to an end in 1893 when George Westinghouse's company was awarded a contract to set up an AC transmission system for demonstration at the Chicago World's Fair. The demonstration gave his company what it needed to continue to grow. Soon, he secured another contract, this time to set up a power generation and transmission station at Niagara Falls to supply power to Buffalo, New York. The war of currents quickly drew to a close, with Westinghouse's AC transmission winning over Edison's DC scheme.
The World After Alternating Current
Today, we take AC power for granted. We run stoves, computers, refrigerators, lights, and many other devices on this power. While the equipment used to generate and transmit the AC power has improved, the same basic philosophy that Westinghouse developed still applies today: generators create AC power which is "stepped up," transmitted across high voltage power lines, and then "stepped down" at our homes so we can use it.
It is very important to note that although we use electricity every day, and usually take it for granted, it can be very dangerous. It is certainly worth learning more about electrical safety. There are a lot of resources at the Electrical Safety Foundation International Web site (http://esfi.org/), including free, downloadable coloring books in English and Spanish. Check them out! Look for "Mr. Plug."
Electrical Safety Story
Here is a true electrical safety story that happened to me (Ray). One day, while walking barefoot outside on damp ground, I reached down to turn on a water spigot. I felt a tingling when I touched the metal faucet handle. I pulled out a meter and measured 10 volts AC between the metal handle and the ground. I called the power company, and they came out to check. At first they said there was a problem with the house wiring, but soon they discovered that their underground cables had started to deteriorate. There was an electrical problem inside their transmission lines. The end result was that they dug up all the cable in the neighborhood and replaced it.
A Cast of Characters
This article has mentioned only a few of the many people who were involved in the "war of currents." Some of these people were unique. Here are a few examples.
• Thomas Edison - When one hears the name Thomas Edison, the image of an inventor is envisioned, and rightly so. Edison had 1,093 U.S. Patents, and many more in Britain, France, and Germany. While many inventors of his time worked through detailed mathematical and scientific studies, Edison was a more of a trial-and-error inventor. He would continue to try new ways and approaches until he eventually achieved the results he wanted.
• Charles Steinmetz - After retiring from General Electric in 1902, Steinmetz went on to teach electrical engineering at Union College. General Electric called him back as a consultant when they ran into a problem with a very complex electrical system. As the story goes, Steinmetz traced the system, determined what component had failed, and marked it with a piece of chalk. He submitted a bill for $10,000 to the company with the following cost breakdown: (1) Making chalk mark: $1. (2) Knowing where to place it: $9,999.
• Nikola Tesla - Tesla was a most unusual person with many strange personality quirks. When traveling, he was adamant that his hotel room number had to be divisible by the number three. He spent the last ten years of his life living on the 33rd floor of the Hotel New Yorker in room 3327, which is divisible by three. He was a very quiet, reclusive person, but well spoken of when he appeared at social events. Although soft-spoken, he let people know that he detested jewelry, especially pearl earrings, ridiculed the way some people dressed, and had a dislike for overweight people.
• George Westinghouse - The name Westinghouse is synonymous with electricity, but do you know how George got his start? When Westinghouse was in his early 20s, he witnessed an accident where two trains hit each other head-on. The engineers could see each other, but they couldn't stop the trains. Westinghouse saw the brakeman running from car to car, applying the brake on each one individually. Using his knowledge of steam, he invented the Westinghouse Steam and Air Brakes, which allowed the brakeman to pull one switch and have pressure, through hoses running between cars, to apply all the brakes at once.
Ray and Gale Lawson have been homeschooling their three children since 1995. Ray holds a B.S. in Electrical Engineering from the Virginia Military Institute and works for Savannah River Nuclear Solutions, LLC. Gale holds a B.S. in Mechanical Engineering from the University of South Carolina and is full-time mom and teacher. They are members of Breezy Hill Baptist Church in Graniteville, SC. Questions, comments and suggestions are always welcomed and can be e-mailed to them at email@example.com (Ray) or firstname.lastname@example.org (Gale).
Originally published in the May/Jun '09 issue of Home School Enrichment Magazine.
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