- The vast majority of our
electrical distribution systems use 3-phase electricity,
but how does it work? How was it invented and who invented it? Ready for the surprising, but a little bit complicated story. And also to the answer of why
some countries use 50 Hertz and some country use 60 Hertz, and one country uses half and half. Ready, let's go. ♪Electricity ♪ ♪ Electricity ♪ ♪ Electricity ♪ ♪ Electricity ♪ In order to tell the story of 3-phase electrical distribution, I think I need to tell a little bit about 3-phase generators and motors. And in order to tell that story, I wanna talk a little bit about the guy named George Westinghouse and 2-phase AC generators and motors, which arguably begins in April, 1888. At this time, Westinghouse
had been electrifying cities with single-phase alternating
current AC for two years, but Edison had only
really been upset about it for about four months, when a syndicate coordinated
the copper market, which increased the cost of DC, which used about three times the copper in comparison with AC. However, Westinghouse had a problem that had nothing to do with Edison's irer. He didn't have a way
to convert electricity that went back and forth
AC to motion that went in the circle for meters
and electrical motors. Westinghouse was initially
mostly concerned with the meter because if he didn't have a meter, then he had to charge a flat
rate for the electricity, which incentivize people to use as much electricity as possible. Luckily in April of 1888, an employee named Shallenberger
dropped the spring near two pieces of equipment and found that the dropped spring started to spin. Within a month, Shallenberger
had a working meter and by August, they had a system on the market. The meter, which operated at
133 Hertz was very popular and sold 120,000 units in just 10 years. Now, Westinghouse had an AC meter, but he was still looking for an AC motor, or something that could
do industrialize work with alternating current. Then, a few weeks after
Shallenberger dropped that spring, Westinghouse heard from another employee that employee's former professor, an Italian scientist named
Galileo Ferraris had created a new type of AC electricity
and a corresponding AC motor. Ferraris' idea required
a special generator, which generates electricity
with two separate sets of coils, A and B at 90 degrees to each other. These coils are identical and electrified by the same electromagnet. So they have identical
current induced in them with the same frequency. In fact, the only
difference is their timing of their maximum value or their phase. Because these two sets of coils
have two different phases, this is now called a 2-phase generator. In order to make a 2-phase motor, Ferraris then connected the
two AC current at 90 degrees around the object that he was attempting to rotate called the rotor. The AC current in the coils
then induces a current in the rotor and the force
between the alternating current from the sets of wires and the
induced current in the rotor is what causes the rotor to spin. Ferraris didn't patent his idea, as he didn't think it would
work on an industrial scale, but Westinghouse paid him a
thousand dollars for it anyway, even though Ferraris offered it for free. At the same time May,
1888, Westinghouse heard that a 32 year old Serbian
inventor named Nikola Tesla was demonstrating to the American Institute
of Electrical Engineers, a 2-phase AC motor and generator where the motor was powerful
and could be used in industry. According to Tesla, this motor and generator were
exactly the same as Ferraris' 2-phase motor and generator. "Professor Ferraris not
only came independently to the same theoretical results, but in a manner identical
almost to the smallest detail." Nevertheless, Tesla
owned the American patent for this motor and generator. And despite the fact that
Westinghouse's lawyer thought the price the Tesla was
asking was monstrous, Westinghouse felt that, "The Westinghouse Electric
Company cannot afford to have others own the
patents that are necessary to enable it to make motors to work on the alternating current system." Therefore, on October, 1888, George Westinghouse paid
Nikola Tesla and his company a whopping $170,000 for the motor, equivalent of around $5 million today with a further $2:50 cents
per horsepower promoter sold in perpetuity. This was an incredible amount of money. And in 1900 Nikola Tesla said, "Had other industrial firms
and manufacturers been as just and liberal as Mr. Westinghouse, I would have had many
more of my inventions in use than I now have." However, despite pouring
an extra $300,000 in trying to get Tesla's motor to
work on an industrial scale, they couldn't get it functioning, partially because Tesla's
motor was designed at 60 Hertz and Westinghouse wanted
it to be at 133 Hertz to match Shallenberger's meter. In April of 1890, Edison
spy sent him a gleeful note, "Mr. Westinghouse has only one alternating current
experiment which is a failure. And Mr. Westinghouse has quarreled with Mr. Tesla, misspelled Mr. Tesla, who invented the alternate current motor." Despite not having a
working industrial motor and being in a PR "battle" with Edison, Westinghouse's Company was
actually doing really well. For example, between 1886 and 1890, Westinghouse's Company sales
went from $150,000 a year to $4 million a year. Then on November 15th, 1890,
a bank in England collapsed, and the economy in England
and America went with it. Westinghouse had borrowed heavily to fulfill all his orders. And now his company was
on the verge of collapse. The bankers were willing to fund him as long as they had a
different manager saying, well, "Mr. Westinghouse wastes
so much on experimentation, and pays so liberally
for whatever he wishes, a way of service and patent rights." Eventually, Westinghouse
found banks that were willing to fund him and let him
remain as the manager, but he decided to be more economical. So he stopped all
research on Tesla's motor. However, even though Westinghouse's work on making a multi-phase motor
and generator were stopped, there were others that were working on it. One of the most important
arguably, the most important was a 26 year old
Russian-Polish man working for the German company, AEG named Mikhail Dolivo-Dobrovolsky. In late 1888, a few months after Tesla became so famous for his 2-phase motor, Dolivo-Dobrovolsky decided
that, "Tesla's arrangement with two entirely independent currents differing by 90 degrees in their phases was not particularly advantageous as the field around the rotor
would fluctuate by 40%." Dolivo-Dobrovolsky then
mathematically determined that three phases reduce
these fluctuations to 15%. And he began building
generators and motors that had three separate sets of coils. This is when Dolivo-Dobrovolsky came to the remarkable conclusion, the three phase wasn't
just better for motors, but it was a new way of
transmitting electricity with three wires instead of six. This trick is only possible because if you connect three waves that are all 120 degrees
apart at any point, the total would add up to zero. In this way, you can basically
ground three of the six wires and only need three live wires
for transmitting electricity. This is very important because with transmitting electricity, the question is often is
how to lower the cost, which usually means how
do you lower the amount of copper needed. With 3-phase power, you can reduce the amount of wire needed for transmission by 50%, and you can still use all three phases to power high-voltage 3-phase motors. Not only that, but in August
of 1889, Dolivo-Dobrovolsky also patented two types
of 3-phase transformer called delta and star or wye
for the shapes they make. With these transformers, the three phases can be safely transformed to higher voltages and low current for long distance transmission
without much loss, and then transformed
back to lower voltages to be safely used. You might be wondering how
Dolivo-Dobrovolsky managed to light light bulbs
with a single live wire, and the answer is he didn't. Instead he used the single
live wire to the bulbs with a return of a neutral wire, which is a wire that is created so that if the three
phases are in balanced, there's no current in them, but they can still complete the circuit. Not only that, but Dolivo-Dobrovolsky also figured out his 3-phase motor was not very efficient as it induced circular
currents called eddy currents in the rotor, the part that spun, which worked against
the motion of the rotor. To reduce the amount of eddy
currents, Dolivo-Dobrovolsky started to put a series of
parallel slits in the rotor, which he patented in 1889. With these slits, the rotors start to look
like large cages and in 1894, the English scientist
Silvanus Thompson called it a, "Sort of squirrel cage"
as it look large enough to hold a squirrel, I
guess, and the name stuck. Squirrel-cage motors are mainstay
in electrical engineering, and according to a
textbook I found from 2017, Dolivo-Dobrovolsky designs
from the 1890s are, "So perfect that they
remain virtually unchanged for more than a hundred
years of their existence." Back in 1890, Dolivo-Dobrovolsky's motor and transmission system impressed an intense looking man
named Oskar Von Miller, who was the technical director of an upcoming Frankfurt
Electrical Exposition. Miller had initially hoped to
use high voltage DC powered by a generator at a waterfall, but the closest waterfall
with a nice cement factory next to it with a turbine they could use, was in Lauffen, Germany, a full 175 kilometers away. Initially, Miller went to a Swiss engineer named Charles Brown, whose company had been
experimenting with long distance DC from hydroelectric plants, but after some
deliberations, Miller decided to use the exciting new
3-phase transmission system. So he brokered an unusual
deal between Brown's company, Dolivo-Dobrovolsky's company,
the German government, and the cement factory to make
this technological advance. Dolivo-Dobrovolsky and Brown then created 3-phase electricity with the generator powered
by the waterfall in Lauffen, then use the star transformer
to step up the voltage from 55 volts to the startlingly high at the time 8,500 volts, and then use the only three
live wires at that high voltage to the town of Frankfurt. This super high voltage was
needed because they needed the thinnest wire possible. Shoot, even was five
millimeter thick wire, they still use 60 tons of copper. Dolivo-Dobrovolsky and Brown then used another star transformer
to step down the voltage to a round 65 volts where they used it to
electrify a sets of lights, as well as a 3-phase 100 horsepower motor that powered an artificial waterfall. I love that they used a real waterfall to create 3-phase electricity, to transform it 175 kilometers
away to make a motor to make an artificial waterfall. I just think that's kind of cool. This system that most scientists
believe would not work at all over long distances made that impressive distance
with 74% of its power intact and was heralded as, "Nothing
short of magnificent." An account in the "Electrical
Engineering Magazine" beamed, "I do not think I am guilty
of exaggeration in expressing an opinion that the
Lauffen-Frankfurt transmission is the most difficult and
most momentous experiment made in technical electricity since that mysterious
natural force has been made serviceable to mankind." This is the first electrical
distribution system that in any way resembles
modern electrical distribution, and we still use 3-phase,
delta transformers and star or wye transformers in
this way to this very day. However, don't be confused by the fact that most of your household
plugs have three plugs to think you're getting
three phases in each plug. In reality, most household plugs actually only get one live wire. And the other two plugs are
the neutral and the ground wire or a wire connected to large
metal stick in the ground. However, Dolivo-Dobrovolsky
was not particularly adept at explaining the
advantages of his system, and many people got confused
between 2-phase and 3-phase, which all started to be
called polyphase current. Another name coined by Silvanus
Thompson that we still use to this very day. In addition, apparently
unknown to Dolivo-Dobrovolsky, his partner in this
transmission, Charles Brown, jealous of all the attention that Dolivo-Dobrovolsky was getting and three phase was getting embed an op-ed in October, 1891 that said, "The adoption of three
phase current only increased the difficulties to be met and all the real constructive
improvements demonstrated the Frankfurt exhibition were almost without exception due to him." In addition, Brown claim that, "The 3-phase current as
applied to Frankfurt is due to the labors of Mr. Tesla and will be found clearly
specified in his patents." Now, you might be wondering
what Brown was talking about with that last comment. So let me explain. See it turns out that back in 1888, Tesla not only patented a
2-phase generator motor, but also a 3-phase generator motor. If Dolivo-Dobrovolsky had known
about Tesla's 3-phase motor, he might have emphasized
that Teslas had six wires, not three, and the advantage of the 3-wire 3-phase
transmission system, but he didn't and instead focused on
the advantages of 3-phases for the motor over 2-phases,
which weakened his claim. As Dolivo-Dobrovolsky did not
speak English and Brown did, and the system was really so complex, many people started to
believe that Tesla invented all of 3-phase transmission and ignored the influence
of Dolivo-Dobrovolsky. This all might've been sorted out in time if on May 20th, 1891, about a week after the Fair
open Nikola Tesla's backers, hadn't pushed him into
giving his first talk on his newest device, the Tesla coil. The Tesla coil was an instant
success on a global scale. 3-phase could reduce the wires by 50%, but Tesla coils could
light a bulb with no wires if held near the coil. The world went into,
basically, a Tesla mania and as an article for the "Electrical
Engineer Magazine" put it, "No man of our age has achieved such universal scientific
reputation in a single stride as this gifted young electrical engineer." It was at this pivotal time
that George Westinghouse decide to reinvest money into making
a 2-phase motor that worked on an industrial scale. Part of his motivation was that one of his engineers convinced him that 60 Hertz could travel longer distance with less loss than 133 Hertz. And another engineer named Benjamin Lamme claimed he could improve
Tesla's motors winding and make them work for industry. With an agreement from
Tesla and his backers, Tesla's backers by the way
owned 54% of this patent, Westinghouse was allowed to
drop any per horse power payment for the Tesla motors. And in late 1891,
Benjamin Lamme was allowed to build his 2-phase AC motor and succeeded in creating a 2-phase motor that was industry ready
by the beginning of 1892, which according to Lamme was
the first induction motor made at Westinghouse Corporation, "Which bears any close
resemblance to the modern type," As the 1893 Chicago's
World Fair approached, Westinghouse had a meeting
about how to promote their new Tesla motors and
Benjamin Lamme suggested that they make a fad out
of polyphase generators, "So that everyone would buy them and the motor question
would soon settle itself." Years later, Lamme recalled that, "Instructions were given immediately to get out a standard line
of polyphase generators and push them on any and every occasion." However, Westinghouse realized for the fair he had a problem. He did not have any
powerful 2-phase generators and he didn't have
enough time to make one. And he certainly didn't
have any 3-phase generator. According to Lamme, Westinghouse suggested they use two separate single-phase generators that were staggered 90 degrees apart as, "A step towards a coming
polyphase supply system." With this bit of subterfuge, he actually even posted a sign at the fair that said that the fair was powered with, "Tesla's Polyphase system." Westinghouse also invited
Tesla to give demonstration at the Westinghouse Pavilion at the fair, and basically promoted
his connection to Tesla at every term. Meanwhile, in 1892, the
year before the fair, Edison's General Electric had
merged with another company and Thomas Edison was fired and
his company dropped his name and became plain old
General Electric or GE. Freed from Edison's prejudice against AC, General Electric went from
a basically all DC company to one of the leaders of 3-phase AC. According to Lamme, who became the chief
engineer at Westinghouse, "There were two polyphase
schools, so to speak, namely the two phase and the three phase. The Westinghouse Company
was known as the advocate of the two phase polyphase systems, although it built both, whereas
General Electric Company was considered as favoring three-phase, although it also built both." After the fair, Westinghouse
put a lot of money into suing companies for Tesla's two phase
and three phase patents. In April, 1896, Westinghouse pay Tesla $216,600 for all his multi-phase
patents in a contract to be shared with GE, which basically left
both companies free to do whatever multi-phased
system they wanted to and gave both companies, which basically controlled
the electricity market, huge incentives to talk
up Tesla's inventions and downplay Dolivo-Dobrovolsky's. Meanwhile, Dolivo-Dobrovolsky
continued to work for AEG as their head engineer and
helped his company become a leader of electrical distribution in Europe and Asia and Africa. As Dolivo-Dobrovolsky experimentally knew that higher frequency caused
more loss in the lines, he first used 40 Hertz, however, eventually he decided
it blinked unpleasantly, so he switched it to 50 Hertz
where it remains to this day. Tesla on the other hand,
insisted on 60 Hertz, where it means in the United States and in countries originally
supplied electricity by GE or Westinghouse. One of the strangest examples of this is the country of Japan, where Dolivo-Dobrovolsky's
company AEG provided the electricity for Tokyo
in 1895 at 50 Hertz, and GE provided the electricity at Osaka in 1896 at 60 Hertz. And now the entire
country is split in two, half at 50 Hertz and half at 60 Hertz. In 1914, World War I began and Dolivo-Dobrovolsky wisely decided that Germany wasn't a safe
place to be for a Russian man and spent much of the war in Switzerland, where he dropped his Russian
citizenship for a Swiss one. He returned to Germany
in 1918 when Russia ended its participation in World War I, as they were busy with
the Russian Revolution. However, by then Dolivo-Dobrovolsky
was having heart issues and he died from heart
problems in November, 1919. The Germans in the middle of
losing World War I weren't particularly invested in talking
about the accomplishments of a Russian-Polish man who abandoned them in their hour of need. And the Russians were
pretty busy with revolution to wanna honor man who'd
mostly accomplished things in Germany, had revoked
his Russian citizenship and hadn't participated
in their revolution. And Americans were wholly
invested in the idea that Tesla had invented
all of polyphase current and transmission as GE and
Westinghouse owned those patents. Although Dolivo-Dobrovolsky's
death was remarked upon and people mourned his passing, there wasn't an acknowledgement
of his accomplishments, which were varied. In conclusion, if you want to ask who invented the first
3-phase motor and generator, the answer is clearly pretty Nikola Tesla, who patented a 3-phase
motor and generator in 1888, but if you ask who was
the first to demonstrate 3-wire 3-phase electrical
generation distribution, transistors and power, as well as the squirrel-cage
motor and more, the answer is different:
Mikhail Dolivo-Dobrovolsky. As Dolivo-Dobrovolsky wrote in 1891, "Though the scientific values of the discoveries of Professor
Ferraris and Mr. Tesla must not be lessened, yet the merit of the practical working out and execution of the rotary current three-phase
system is undoubtably due to my company, that brought the whole system to such a pitch of perfection." If you're wondering who
figured out the science of why higher frequencies cause
higher losses in the lines and the scientists who
made GE go from all DC to a leader in three phase AC, it's another scientist who is
not as famous as he should be. One of my favorites, the charismatic and quirky
"Wizard of Schenectady" Charles Steinmetz, and his story is next time
on the "Lightning Tamers." If you're interested in what
inspired Ferraris and Tesla to invent the 2-phase motor and generator, which really was a major invent, I have discovered that Ferraris
was inspired by optics, particularly polarization of
light and Tesla was inspired by something called a Arago's wheel. If you want to know more about it, I made a video about it
and you can watch the video if you join my mailing
list link down below as well as a script for that video. As an extra incentive, you will be among the first
to know when my book comes out all about the history of
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