- Carlson, W. Bernard.
Tesla: Inventor of the Electrical Age.
Princeton: Princeton University Press, 2013.
ISBN 978-0-691-16561-5.
-
Nicola Tesla was born in 1858 in a village in what is now Croatia,
then part of the Austro-Hungarian Empire. His father and
grandfather were both priests in the Orthodox church. The family
was of Serbian descent, but had lived in Croatia since the 1690s
among a community of other Serbs. His parents wanted him to
enter the priesthood and enrolled him in school to that end. He excelled in
mathematics and, building on a boyhood fascination with machines
and tinkering, wanted to pursue a career in engineering. After
completing high school, Tesla returned to his village where he
contracted cholera and was near death. His father promised him
that if he survived, he would “go to the best technical
institution in the world.” After nine months of illness,
Tesla recovered and, in 1875 entered the Joanneum Polytechnic
School in Graz, Austria.
Tesla's university career started out brilliantly, but he came
into conflict with one of his physics professors over the
feasibility of designing a motor which would operate without
the troublesome and unreliable commutator and brushes of
existing motors. He became addicted to
gambling, lost his scholarship, and dropped out in his third
year. He worked as a draftsman, taught in his old high school,
and eventually ended up in Prague, intending to continue his
study of engineering at the Karl-Ferdinand University. He
took a variety of courses, but eventually his uncles withdrew
their financial support.
Tesla then moved to Budapest, where he found employment as
chief electrician at the Budapest Telephone Exchange. He
quickly distinguished himself as a problem solver and innovator and,
before long, came to the attention of the Continental Edison Company
of France, which had designed the equipment used in Budapest. He
was offered and accepted a job at their headquarters in
Ivry, France. Most of Edison's employees had practical, hands-on
experience with electrical equipment, but lacked Tesla's
formal education in mathematics and physics. Before long, Tesla
was designing dynamos for lighting plants and earning a
handsome salary. With his language skills (by that time, Tesla
was fluent in Serbian, German, and French, and was improving his
English), the Edison company sent him into the field as a
trouble-shooter. This further increased his reputation and,
in 1884 he was offered a job at Edison headquarters in New York.
He arrived and, years later, described the formalities of
entering the U.S. as an immigrant: a clerk saying “Kiss
the Bible. Twenty cents!”.
Tesla had never abandoned the idea of a brushless motor. Almost
all electric lighting systems in the 1880s used
direct current (DC):
electrons flowed in only one direction through the distribution
wires. This is the kind of current produced by batteries,
and the first electrical generators (dynamos) produced direct
current by means of a device called a
commutator.
As the generator is turned by its power source (for example, a steam
engine or water wheel), power is extracted from the rotating commutator
by fixed brushes which press against it. The contacts on the
commutator are wired to the coils in the generator in such a way
that a constant direct current is maintained. When direct current
is used to drive a motor, the motor must also contain a commutator
which converts the direct current into a reversing flow to maintain
the motor in rotary motion.
Commutators, with brushes rubbing against them, are inefficient
and unreliable. Brushes wear and must eventually be replaced, and
as the commutator rotates and the brushes make and break contact,
sparks may be produced which waste energy and degrade the
contacts. Further, direct current has a major disadvantage
for long-distance power transmission. There was, at the time,
no way to efficiently change the voltage of direct current. This
meant that the circuit from the generator to the user of the
power had to run at the same voltage the user received,
say 120 volts. But at such a voltage, resistance losses in
copper wires are such that over long runs most of the energy
would be lost in the wires, not delivered to customers. You can
increase the size of the distribution wires to reduce losses, but
before long this becomes impractical due to the cost of copper
it would require. As a consequence, Edison
electric lighting systems installed in the 19th century had
many small powerhouses, each supplying a local set of
customers.
Alternating
current (AC) solves the problem of power distribution. In 1881
the electrical transformer had been invented, and by 1884
high-efficiency transformers were being manufactured in Europe.
Powered by alternating current (they don't work with DC),
a transformer efficiently converts current from one voltage and current to
another. For example, power might be transmitted from the generating
station to the customer at 12000 volts and 1 ampere, then stepped
down to 120 volts and 100 amperes by a transformer at the customer
location. Losses in a wire are purely a function of current, not
voltage, so for a given level of transmission loss, the cables
to distribute power at 12000 volts will cost a hundredth as
much as if 120 volts were used. For electric lighting,
alternating current works just as well as direct current (as
long as the frequency of the alternating current is sufficiently
high that lamps do not flicker). But electricity was increasingly
used to power motors, replacing steam power in factories. All
existing practical motors ran on DC, so this was seen as an
advantage to Edison's system.
Tesla worked only six months for Edison. After developing an
arc lighting system only to have Edison put it on the shelf
after acquiring the rights to a system developed by another
company, he quit in disgust. He then continued to work on
an arc light system in New Jersey, but the company to which
he had licensed his patents failed, leaving him only with a
worthless stock certificate. To support himself, Tesla worked
repairing electrical equipment and even digging ditches, where
one of his foremen introduced him to Alfred S. Brown, who
had made his career in telegraphy. Tesla showed Brown one
of his patents, for a “thermomagnetic motor”, and
Brown contacted Charles F. Peck, a lawyer who had made his
fortune in telegraphy. Together, Peck and Brown saw the
potential for the motor and other Tesla inventions and in
April 1887 founded the Tesla Electric Company, with its
laboratory in Manhattan's financial district.
Tesla immediately set to make his dream of a brushless AC motor a
practical reality and, by using multiple AC currents, out of phase with
one another (the
polyphase system),
he was able to create a magnetic field which itself
rotated. The rotating magnetic field induced a current in the
rotating part of the motor, which would start and turn
without any need for a commutator or brushes.
Tesla had invented what we now call the
induction motor.
He began to file patent applications for the motor and the
polyphase AC transmission system in the fall of 1887, and by
May of the following year had been granted a total of seven
patents on various aspects of the motor and polyphase current.
One disadvantage of the polyphase system and motor was that it required
multiple pairs of wires to transmit power from the generator to the
motor, which increased cost and complexity. Also,
existing AC lighting systems, which were beginning to come into use,
primarily in Europe, used a single phase and two wires. Tesla
invented the
split-phase motor,
which would run on a two wire, single phase circuit, and this was
quickly patented.
Unlike Edison, who had built an industrial empire based upon
his inventions, Tesla, Peck, and Brown had no interest in
founding a company to manufacture Tesla's motors. Instead,
they intended to shop around and license the patents to an
existing enterprise with the resources required to exploit
them. George Westinghouse had developed his inventions of
air brakes and signalling systems for railways into a
successful and growing company, and was beginning to compete
with Edison in the electric light industry, installing AC
systems. Westinghouse was a prime prospect to license the
patents, and in July 1888 a deal was concluded for cash,
notes, and a royalty for each horsepower of motors sold.
Tesla moved to Pittsburgh, where he spent a year working in
the Westinghouse research lab improving the motor designs.
While there, he filed an additional fifteen patent applications.
After leaving Westinghouse, Tesla took a trip to Europe
where he became fascinated with Heinrich Hertz's discovery
of electromagnetic waves. Produced by alternating current at
frequencies much higher than those used in electrical power
systems (Hertz used a spark gap to produce them), here was
a demonstration of transmission of electricity through
thin air—with no wires at all. This idea was to
inspire much of Tesla's work for the rest of his life.
By 1891, he had invented a resonant high frequency
transformer which we now call a
Tesla coil,
and before long was performing spectacular demonstrations
of artificial lightning, illuminating lamps at a distance
without wires, and demonstrating new kinds of electric lights
far more efficient than Edison's incandescent bulbs.
Tesla's reputation as an inventor was equalled by his
talent as a showman in presentations before scientific
societies and the public in both the U.S. and Europe.
Oddly, for someone with Tesla's academic and practical background,
there is no evidence that he mastered Maxwell's theory of
electromagnetism. He believed that the phenomena he observed
with the Tesla coil and other apparatus were not due to the
Hertzian waves predicted by Maxwell's equations, but rather
something he called “electrostatic thrusts”. He
was later to build a great edifice of mistaken theory on this
crackpot idea.
By 1892, plans were progressing to harness the hydroelectric
power of Niagara Falls. Transmission of this power
to customers was central to the project: around one
fifth of the American population lived within 400 miles
of the falls. Westinghouse bid Tesla's polyphase
system and with Tesla's help in persuading the committee
charged with evaluating proposals, was awarded the contract
in 1893. By November of 1896, power from Niagara reached
Buffalo, twenty miles away, and over the next decade extended
throughout New York. The success of the project made polyphase
power transmission the technology of choice for most
electrical distribution systems, and it remains so to this day.
In 1895, the New York Times wrote:
Even now, the world is more apt to think of him as a
producer of weird experimental effects than as a
practical and useful inventor. Not so the scientific
public or the business men. By the latter classes Tesla
is properly appreciated, honored, perhaps even envied. For
he has given to the world a complete solution of the problem
which has taxed the brains and occupied the time of the
greatest electro-scientists for the last two
decades—namely, the successful adaptation of electrical
power transmitted over long distances.
After the Niagara project, Tesla continued to invent, demonstrate his
work, and obtain patents. With the support of patrons such as
John Jacob Astor and J. P. Morgan he pursued his work on wireless
transmission of power at laboratories in Colorado Springs
and
Wardenclyffe
on Long Island. He continued to be featured in the popular press,
amplifying his public image as an eccentric genius and mad
scientist. Tesla lived until 1943, dying at the age of 86 of a
heart attack. Over his life, he obtained around 300 patents for
devices as varied as a new form of turbine, a radio controlled
boat, and a vertical takeoff and landing airplane. He speculated
about wireless worldwide distribution of news to personal mobile devices
and directed energy weapons to defeat the threat of bombers. While in
Colorado, he believed he had detected signals from extraterrestrial
beings. In his experiments with high voltage, he accidently detected
X-rays before Röntgen announced their discovery, but he didn't
understand what he had observed.
None of these inventions had any practical consequences. The
centrepiece of Tesla's post-Niagara work, the wireless transmission
of power, was based upon a flawed theory of how electricity
interacts with the Earth. Tesla believed that the Earth was filled
with electricity and that if he pumped electricity into it at one
point, a resonant receiver anywhere else on the Earth could extract
it, just as if you pump air into a soccer ball, it can be drained out
by a tap elsewhere on the ball. This is, of course, complete nonsense, as
his contemporaries working in the field knew, and said, at the
time. While Tesla continued to garner popular press coverage for
his increasingly bizarre theories, he was ignored by those who
understood they could never work. Undeterred, Tesla proceeded to
build an enormous prototype of his transmitter at Wardenclyffe,
intended to span the Atlantic, without ever, for example, constructing
a smaller-scale facility to verify his theories over a distance of,
say, ten miles.
Tesla's invention of polyphase current distribution and the
induction motor were central to the electrification of
nations and continue to be used today. His subsequent work
was increasingly unmoored from the growing theoretical understanding
of electromagnetism and many of his ideas could not have worked.
The turbine worked, but was uncompetitive with the fabrication
and materials of the time. The radio controlled boat was clever,
but was far from the magic bullet to defeat the threat of the
battleship he claimed it to be. The particle beam weapon (death
ray) was a fantasy.
In recent decades, Tesla has become a magnet for Internet-connected
crackpots, who have woven elaborate fantasies around his work.
Finally, in this book, written by a historian of engineering and
based upon original sources, we have an authoritative and unbiased
look at Tesla's life, his inventions, and their impact upon society.
You will understand not only what Tesla invented, but why, and how
the inventions worked. The flaky aspects of his life are here as
well, but never mocked; inventors have to think ahead of
accepted knowledge, and sometimes they will inevitably get things
wrong.
February 2016 