In short, many of Thomas Edison's most famous inventions - carbon microphone, phonograph, electric light, movie projector - are already obsolete or soon will be not far into the 21st century. On the other hand, fundamental electric technologies, such as 3-phase power distribution, the AC motor, wireless transmission, etc. will be with us far into the future. You may be surprised to learn that all of the latter inventions were strongly influenced by one man, a man many people today have never heard of: Nikola Tesla.
Tesla was Edison's rival at the end of the 19th century - in fact, he was more famous than the Menlo Park wizard throughout the 1890's. Temperamental genius and megalomaniacal huckster, his invention of polyphase electric power alone earned him worldwide fame and fortune. At his zenith he was an intimate of poets and scientists, industrialists and financiers. Yet Tesla died destitute, having squandered both his fortune and scientific reputation.
During his fall from notoriety to obscurity, Tesla created a legacy of genuine invention and questionable prophecy that still fascinates today. His was an age which welcomed science while continuing to embrace the mystical. His reputation resides there still, between fact and fantasy; his legacy, larger than life.
Part One - GeniusOne of Tesla's legitimate accomplishments was the invention of a practical AC motor. At the time it was considered an impossibility and its advent nearly as significant as that of the steam engine which it would widely replace. Tesla's motor signaled the end of the Age of Steam and the dawn of a new Age of Electricity.
Invention of the Polyphase AC Motor (1882)
Since technical school, Tesla had been obsessed with the idea of a commutator-less motor. In his autobiography, Tesla claims that the solution to this problem appeared during a breakdown and in a literal flash of insight. From childhood experience we can all imagine a motor constructed of an inner magnet with poles perpendicular to the axle and surrounded by a second horseshoe magnet mounted to an independent axle. Turning one magnet causes the other to follow by simple attraction. Tesla's insight was to replace the outer magnet with two sets of stationary electromagnets, each supplied with alternating current from sources 90 degrees out of phase. The phase difference creates a rotating field that the inner rotor follows. Tesla had conceived the synchronous AC motor.
Tesla's insight would ultimately make the advantages of AC power usable by industry, with tremendous improvements in the cost and reliability of electricity. But he could convince no one of this at the time. Though the advantages of AC for power transmission were well known and many people were impressed with Tesla himself, he found himself unable to raise the capital to start a company to manufacture his new motor / generator. He went instead to work in the Paris office of a company that used the Edison system.
Working for EdisonWhile in Paris, Tesla was introduced to Charles Batchelor, one of Edison's inner circle. Impressed, he gave Tesla a letter of introduction and encouraged him to set sail for America. Tesla came to America in 1884, the same year as the Statue of Liberty and one year after the Brooklyn Bridge opened. Arriving in New York with nothing but spare change and the clothes on his back, he presented himself and Batchelor's letter of introduction to Edison at his laboratory in Menlo Park. Edison was uninterested in Tesla's plans for AC, but was always looking for another repairmen to keep his generators running smoothly. Tesla soon impressed even the indefatigable Edison by working through the night to have a ship's generators ready for departure the next morning.
The two men could otherwise have hardly been of more different temperaments, however. Edison, of 99% perspiration fame, was a fanatical, slightly uncouth experimentalist, whereas Tesla was cultured, educated in electrical theory, soft spoken and fluid in several languages. He was also perhaps a little naive.
By his own account, Tesla worked hard for Edison and his DC generating system, creating several patented improvements for the Menlo Park Wizard. He proposed additional revisions and enhancements to the Edison dynamo design and asked what they would be worth. "$50,000", was Edison's reply (at least $1M dollars today). Tesla redoubled his efforts and delivered as promised. When he presented his case for payment, though, Edison told him that he just didn't understand American humor and offerred him a modest raise instead.
Tesla Electric and the Induction MotorTesla felt cheated and left Edison to form his first company, Tesla Electric Light and Manufacturing Company to manufacture an improved arc lamp of his own design. Badgering his investors to support development of an AC motor, he soon found himself forced out of his own company and spent the winter of 1886/7 digging ditches.
There are, however, several obvious permutations of the basic synchronous design. One is to replace the rotor magnet with a solid iron rotor and use the iron's ferromagnetic property to generate torque. This is called a reluctance motor. The second possibility is to replace the rotor magnet with an electromagnet powered by battery or, better still, by a small DC generator attached to the same shaft as the primary AC motor. This is referred to as a self-excited synchronous motor.
By demonstrating the ability of a rotating field to spin up a metallic egg placed within its confines, Tesla succeeded in convincing new investors that his new motor offerred a credible alternative to those using DC. Forming the new Tesla Electric Company, he worked feverishly from 1887 onwards filing a wave of patents covering every facet of generation, distribution and use in 2 through N phases. The material he submitted was so unprecedented that the US Patent Office granted his claims in short order.
Westinghouse and the War of the Currents
Battle lines were drawn. Edison was already working hard to publicize safety concerns with the new AC system, much as he had done in his battles with the gas light companies years earlier. In addition to using the bully pulpit of his celebrity to decry its dangers, Edison helped fund the creation of the AC-based electric chair. It was rumored Westinghouse contributed to the defense fund of its first victim. There followed a short competition between the two camps in the electrocution of convicts and small animals.
Westinghouse was a shrewd promoter and meanwhile underbid Edison for rights to wire the Columbian Exposition (Chicago World's Fair) of 1893 using the Tesla system. This exposition, entirely lit by AC and with demonstrations of Tesla's motors (and without mass electrocution of the visiting public!) proved a tremendous success and a turning point in the War of the Currents.
For many years, study had been given to the harnessing of the tremendous power available at Niagara Falls. At the time, the Niagara Power Commission was studying about a dozen proposals for deliver of energy to Buffalo, some 23 miles distant. More than half the proposals were electrical, including a 16kV DC system. DC dynamos had been used at the falls for more than a decade. There were also proposals for hydraulic and mechanical systems. At one point, a pneumatic system proposed by Westinghouse was the leading candidate! (The idea would have been to run a high pressure air pipe and receive the power in Buffalo using almost unmodified steam engines) But Westinghouse and Tesla's triumph in Chicago led to a contract later that year for the first two AC generators at the Edward Dean Adams power station.
The triumph of AC made George Westinghouse even more wealthy and Tesla comfortable. Tesla Electric sold the patents for about $250,000. Tesla would have made at least 10 times that amount in royalties except he renegotiated with Westinghouse when the latter was financially pressed. A pity, since Tesla would become increasingly impoverished in the following years...
Footnote: Westinghouse Electric is no more. After acquiring CBS, the company began divesting itself of all industrial enterprises in 1997, then changed its name to CBS Corporation. The fossil fuels generation business is now part of Siemens; nuclear power generation was sold to British Nuclear Fuels; large industrial motor manufacturing was acquired by TECO (Taiwan) with smaller motors becoming a part of Reliance Electric (a division of Rockwell Automation).
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