Hi
folks.
When
you flip a switch and a lamp illuminates the room, you probably don't give much
thought to how it works or to the people who made it all possible. If you were
forced to thank the genius behind the lamp, you might name Thomas Alva Edison,
the inventor of the incandescent light bulb. But just as influential perhaps
more so was an incredible visionary named Nikola Tesla.
Tesla
arrived in the United States in 1884, at the age of 28, and by 1887 had filed
for a series of patents (7 patents in 3 years!) that described everything
necessary to generate electricity using alternating current, or AC. To
understand the significance of these inventions, you have to understand what
the field of electrical generation was like at the end of the 19th century. It
was a war of currents -- with Tesla acting as one general and Edison acting as
the opposing general.
Edison
unveiled his electric incandescent lamp to the public in January 1880. Soon thereafter,
his newly devised power system was installed in the First District of New York
City. When Edison flipped the switch during a public demonstration of the
system in 1881, electric lights twinkled on and created demand for this
brand-new technology. Although Edison's early installations called for
underground wiring, demand was so great that parts of the city received their
electricity on exposed wires hung from wooden crossbeams. By 1885, avoiding
electrical hazards had become an everyday part of city life; so much so that
Brooklyn named its baseball team the Dodgers because its residents commonly
dodged shocks from electrically powered trolley tracks (really!).
Edison
was a (extremely) staunch supporter of DC, but it had limitations. The biggest
was the fact that DC was difficult to transmit economically over long
distances. Edison knew that alternating current didn't have this limitation,
yet he didn't think AC a feasible solution for commercial power systems. Elihu
Thomson, one of the principals of Thomson-Houston and a competitor of Edison,
believed otherwise. In 1885, Thomson sketched a basic AC system that relied on
high-voltage transmission lines to carry power far from where it was generated.
Thomson's sketch also indicated the need for a technology to step down the
voltage at the point of use. Known as a transformer, this technology would not
be fully developed for commercial use until Westinghouse Electric Company did
so in 1886.
Even
with the development of the transformer and several successful tests of AC
power systems, there was an important missing link- How to use that transmitted
power to get useful work? That link was the AC motor.
While
Edison toiled to commercialize his electric lamp, Tesla worked through a
problem that had intrigued him since he was a student at the Joanneum
Polytechnic School in Graz, Austria. While a student there, Tesla saw a
demonstration of a Gramme dynamo. A dynamo is a generator that uses a
commutator - contacts mounted on the machine's shaft - to produce direct
current instead of alternating current. Tesla mentioned to his instructor that
it might be possible to do away with the commutator, which sparked horribly as
the dynamo operated. This suggestion brought ridicule from his teacher, but it
captured Tesla's imagination.
In
1881, Tesla had an inspired idea: What if one were to change the magnetic field
in the stator of a dynamo instead of altering the magnetic poles of the rotor?
This was a revolutionary concept that turned conventional concept on its head.
Let
us see why it was so amazing. We all know for generation of EMF we need a
conductor, magnetic field and relative motion. Before Tesla, all machines were
working like stationary field and rotating conductor. Tesla was the first one
to imagine rotating field and stationary conductors. This is highly impossible
with DC currents. So Tesla started to search for currents that change
direction. In a traditional dynamo, the stationary stator
provides a constant magnetic field, while a set of rotating windings the rotor turns
within that field. Tesla saw that if this arrangement were reversed, the
commutator could be eliminated.
Of
course, bringing this idea to reality would take years of work. Tesla began in
1882 while employed at Continental Edison Company in Paris. During the day, he
would install incandescent lighting systems based on Edison's DC power system.
In his spare time, he would experiment with AC motor designs. This went on for
two years, until Tesla transferred to the Edison Machine Works in New York
City. By some accounts, Tesla described his ideas about AC to the famed
American inventor, but Edison showed no interest. Instead, he had Tesla make
improvements to existing DC generation plants. Tesla did so, only to be
disappointed when Edison failed to pay him properly. Tesla quit, and the paths
of the two men diverged permanently.
(After
this, they both criticized each other publicly and when they received Nobel
Prize, They refused to receive it together and the end result was no-one got
Nobel Prize. Can you believe that?)
Tesla
received financial backing from Charles Peck, an attorney, and Alfred S. Brown,
a superintendent at Western Union. Peck and Brown helped Tesla establish a
laboratory just a few blocks away from Edison's lab in Manhattan, and
encouraged the young engineer to perfect his AC motor. Tesla did just that,
building what would become known as a polyphase induction motor. The term
polyphase refers to a motor based on multiple alternating currents, not just
one. The term induction refers to the process whereby the rotating stator
magnets induce current flow in the rotor. Tesla's original motor was a
two-phase version that featured a stator with two pairs of magnets, one pair
for each of two phases of AC.
In
1887, Tesla filed for seven U.S. patents describing a complete AC system based
on his induction motor and including generators, transformers, transmission
lines and lighting. A few months later, Tesla delivered a lecture about his
revolutionary new system to the American Institute of Electrical Engineers. The
lecture caused a sensation and, despite an anti-AC campaign initiated by
Edison, convinced many experts that an AC power system was more than just
feasible - it was far superior to DC.To bring a good idea to market, it takes
some clout. In this case, the clout came from an inventor who made a fortune in
the railroad industry.
George
Westinghouse, whose own electric company was struggling to work out the details
of a successful AC power system, heard about Tesla's 1888 lecture and
immediately was intrigued. When Peck and Brown approached Westinghouse about
commercializing Tesla's inventions, the entrepreneur responsible for the
railroad air brake made a generous offer. He agreed to pay $25,000 in cash, as
well as $50,000 in notes and a small royalty for each horsepower of electricity
originating from the motor.
Westinghouse
carried Tesla's inventions back to Pittsburgh, Penn., where he hoped to use the
technology to power the city's streetcars. Tesla followed, and as an employee
of the Westinghouse Electric Company, consulted on the implementation. The
project didn't proceed smoothly, and Tesla frequently battled with Westinghouse
engineers. Eventually, however, everyone pulled together to come up with just
the right formula: an AC system based on three-phase, 60-cycle current. Today,
almost all power companies in the United States and Canada supply 60-cycle
current, which means the AC completes 60 changes of direction in one second.
This is known as the frequency of the system.
By
the early 1890s, Edison and the supporters of DC felt genuinely threatened.
They continued to make claims that AC was dangerous and pointed to a disastrous
electrocution attempt in 1890 as evidence. But they suffered a severe blow in
1893, when Westinghouse won the bid to illuminate the Chicago World's Fair. His
competition was General Electric (GE), the company formed by the merger between
Edison General Electric and Thomson-Houston. GE was the leading torchbearer for
DC-based power (and still is one of the most awesome companies for us).
Westinghouse won the bid on cost, but when President Grover Cleveland flipped a
switch to light 100,000 incandescent lamps across the fairgrounds, very few
doubted the superiority of AC power.
Westinghouse
mollified many remaining doubters in 1895 by designing a hydroelectric plant at
Niagara Falls that incorporated all of the advances made in AC. At first, the
plant only supplied power to Buffalo, New York. But it wasn't long before power
was being transmitted to New York City. (The generators still working have
Tesla’s name inscribed in their name plate.)
In fact, it can be said that Tesla's AC motor
and poly-phase AC system won the war of currents because they form the basis of
all modern power generation and distribution. However, direct current
--Edison's baby --didn't disappear completely. It still operates automobile
electrical systems, locomotives and some types of motors and long-distance
transmission.
These
were some history lessons you should know if you call yourself an electrical
engineer. Do feel proud to carry on this legacy and thank you for your time.
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