Nikola Tesla Books
A Synopsis of the Engineering Contributions of Nikola Tesla In order to understand the impact of Tesla's work on our lives as we live them today, it is necessary to describe the state of the Electrical Power Industry before Tesla. Faraday (1831) had discovered the fundamental relation between electric and magnetic fields, and showed that a time changing magnetic field would induce an electric field in a circuit, and that moving a conductor in a magnetic field would cause a current to flow in it. Sources of current (batteries) were available based on work of Galvani and Volta, and generators had been developed (Holmes-1857) to produce Direct Current, used for electric lighting (carbon arc lights). In 1866, Wilde produced an AC generator. In 1870, a DC generator was developed by Gramme, and in 1873 Fontaine and Gramme showed that the DC generator could be used as a motor. In 1875, Crookes showed that a high voltage discharge through a gas would produce a luminous discharge (which Tesla later improved and expanded). In 1878, Jablochkoff produced a practical form of arc light used on Thames embankment. In 1879, Swan developed the incandescent lamp and, in the same year, Edison developed the high resistance filament lamp operating on D.C. This device, and the D.C. motor, required a system in which the power generated was distributed to the user at a constant voltage, with various devices. connected to the same voltage source (the parallel circuit; in contrast to the series circiut, in which the devices are connected one after the other. This (series) circuit had the advantage that the power source had to supply a relatively low current, but the voltage required was the sum of all the voltages for each device. This was a highly impractical scheme, and was quickly discarded (old fashioned Christmas lights are an example). However, this parallel system required relatively large currents to be generated and transmitted. Unfortunately, the power loss in transmission varies as the square of the current, so transmission distances were inherently short (of the order of 30 miles or so). This required, then, a system of many generators located near the users. In New York City there were about 2000 generating stations located in the city. It was recognized that AC transmission would be a great advantage because power could be generated, and then transformed to a high voltage (utilizing the transformer invented by Goulard and Gibbs in 1882) which could carry a high power at low current with smaller losses, and then transformed down to useable voltage near the user (which is the system we use today). Unfortunately, there was no practical AC motor (ones existing at that time would not self-start, and would not come up to synchronous speed without an auxiliary DC winding). Further, both the AC and DC motors utilized the commutator, or brush contact systems, which led to a great deal of arcing, with resulting power loss (as well as considerable fire hazard) and low efficiency. We now recognize that power is a fundamental factor in the material porgress of civilization. Only an abundant and economically realizable power source can supply the expanding requirements for operating factories, transporation, lighting, heating and communications. The necessity was (and is) for a means of converting a primary source of energy, wherever it was located, into electrical power, and a means of transmitting it to the place where it was needed. (It should be noted that AC transmission first took place in Buffalo, N.Y. on Thanksgiving Day, 1886.) In 1881, Tesla joined the Austro-Hungarian State Telephone Department - patented his first patent for a telephone repeater - then traveled to Paris, with Edison Electric Light Co., then spent two years in Strasboug. It is clear that he was then working on his concept of a commutatorless motor. In 1884, he traveled to the United States, and was employed at Edison Machine Works in New York City. It is here that his divergence of opinion with Edison (over the DC vs. AC systems) became ever more apparent, and he soon left to form the Tesla Electric Light Company (1887). In that year he filed his major patents in the field of production, transmission and utilization of electiric power. They included: 1) Development of the Rotating Magnetic Field 2) Polyphase systems 3) Invention of the induction motor 4) Transmission by polyphase systems 5) Development of the multi-phase generator He presented these concepts at a meeting of the American Institute of Electrical Engineers in May 1888, in what has been called "the single most important paper ever presented at a technical meeting." Tesla's idea was that the generation of a rotating magnetic field in space by energizing the machine from a three-phase source would cause the rotation of a coil (squirrel cage) placed in that field, without a commutator, thus avoiding the losses. It should be noted that Tesla did notcreate the concept of a rotating field (which J.J. O'Neill's biography implies), instead he showed how to generate one without moving connectors. At the time, AC transmissions had been achieved using single phase at 133 hertz. The Tesla system would not work well (at that time) on single phase, so a competition developed in which the Tesla system won out, and the power system we use today (Tesla System) became preeminent. In 1888, George Westinghouse secured the patents and engaged Tesla to work on the further developments of this system. In 1891, a three-phase system was inaugurated in Frankfurt, Germany, based on the Tesla System. In 1886, a charter had been obtained for the electrification of Niagara Falls. An early plan (Evershed Plan) called for many separate canals supplying separate water turbines, each developing 500 hp. This system was 18
