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Prior to 1800,
many mariners had observed that nearby lightning strikes seemed to
momentarily affect the position of their compass needles, and that this also
occurred during the formation of St. Elmo's fire on their ship's masts.
Lightning discharges were also known to magnetize knives and other iron or
steel objects. However, no-one had been to reconcile these magnetic effects
with the flow of electric currents. |
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1799 - 1800 ~ Allesandro
Volta.... |
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1802 ~ ROMAGNOSI
vaguely observes that the connection of a Voltaic
Pile (i.e., battery) to a closed electrical circuit seems to
affect a nearby compass needle (he made mention of this in an
obscure Italian publication), but he does not realize the possible
connection between Electricity and Magnetism.
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1819 ~ DEFLECTION OF A
MAGNETIC NEEDLE BY AN ELECTRIC CURRENT
OERSTED
(?accidentally?) discovered this effect (Electromagnetism)
in
the winter of 1819 during a demonstration to his students of the heating
of a platinum wire by the electric current from a voltaic pile. He
had planned to demonstrate both the heating of the wire and to also to
carry out some general demonstrations of magnetism, for which he had
provided a compass needle mounted on a wooden stand. While performing the
wire heating demonstration, Oersted noted to his surprise that every time
the electric current was flowing, the nearby compass needle moved to a
position more perpendicular to the wire.
However, Oersted does not seem to have immediately understood that the electric current actually
generated a magnetic field about itself (i.e., the
circular magnetic field surrounding an electrical conductor when current
is flowing.) Three months later (March, 1820), having confirmed the effect
through further experiments, he further investigates this phenomena and in
the summer he publishes a treatise thereon (in Latin
and in almost unreadable natural philosophical terminology) without any
explanation for the effect and sends it to many leading scientific
journals and to a number of scientists. Oersted's announcement appeared in
the Annales de Chimie et de Physique in July of 1820 and gains further
publicity when the distinguished scientific statesman François Arago calls
attention to the discovery at a meeting of the Académie des Sciences in
Paris in September, 1820.
Shown on
the left is a lithograph depicting Oersted's original demonstration and on the
right is an 1851 example of an experimental apparatus to demonstrate
this electromagnetic effect.
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1820 ~ GALVANOMETER
SCHWEIGGER creates the
world's first Galvanometer (i.e., galvanoscope.)
While experimenting with electromagnetism,
Schweigger became delighted when the deflection of a magnetic needle was
doubled as long as the needle's position was maintained within the plane
of a doubled loop of wire (i.e., a coil.) Schweigger then wound a conducting wire
on itself for 100 turns to provide for an effect far greater than a single
loop of wire. Applying Oersted's principle to his device, he reported the
operation and effect of his galvanomagnetic multiplier just two months
after Oersted's announcement in July 1820 of his experiments with
electromagnetism. Schweigger presented a paper on his discovery at the
University of Halle on 16 September 1820, and published the same in the
November 1820 issue of Literary Gazette. Schweigger also called his new
device an electromagnetic multiplier or galvanometer multiplier (or a
galvanomagnetic kondensator.) |
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1820+ AMPERE,
who had been in the audience when Arago announced Oersted's discovery in
Paris, investigates electromagnetism and presents his interpretation
thereof in early 1821. Besides confirming Oersted's results, Ampere made
careful studies of the effects of electric currents on one another. He
found that if currents traveled in the same direction along two parallel
wires, there was attraction between them; if the currents traveled in the
opposite directions there was repulsion. Over the next six years, he
worked out a detailed mathematical treatment of the interactions, on the
basis of the assumption that current-carrying elements of the wire
interacted with one another according to the inverse square law. By
integrating the effects of all the elements he arrived at expressions that
were consistent with the experimental results and by 1827 he had developed a comprehensive Electrodynamic
Theory with the aid of his unique apparatus (i.e., Ampere's
Table.)
A drawing of Ampere's original table is shown on the left, as well
as an example of his table circa. 1865 on the right.
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1820 ~ ARAGO and DAVY
produce the spiral wound planar solenoid
(one from Faraday's laboratory circa. 1824 is shown here.) Wollaston
advances the possibility of electromagnetic rotations, and he and Davy attempt to cause
the rotation of an electrical conductor about its own axis,
but fail.
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1820 ~ AMPERE (as well as Arago and Davy)
develop the helical air-cored solenoid. The example on the left is from
Faraday's laboratory circa. 1824, the example on the right is circa. 1851.
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1821 ~ ROTATION OF A CONDUCTOR IN A MAGNETIC FIELD
(FIRST ELECTROMAGNETIC MOTOR & FIRST ACYCLIC / HOMOPOLAR MOTOR)
FARADAY is asked to investigate
electromagnetism and quickly produces his "Electromagnetic
Rotator", which is the world's first Electric
Motor (and is powered by DC and is
non-commutated), and it is
also the world's first electromechanical power
converter that is both homopolar
in structure and "Acyclic" in
operational nature. Faraday then went on to cause a magnet to rotate
around an electric current-carrying (DC) wire, another case of a homopolar and acyclic apparatus. Shown on the left is a drawing of
Faraday's apparatus for producing the rotation of an electric
current-carrying conductor around a magnetic pole (which was manufactured
and sold to other investigators in 1822.) Shown on the right is a
two-figure drawing of an 1850's modification of Faraday's two
electromagnetic rotator apparatus. Fig. 1 shows the rotation of magnets
around a conductor and Fig. 2 shows the rotation of conductors around a
magnet.
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1822 ~ BARLOW produces
electromagnetic rotation with his star-shaped wheel ("Barlow's
Wheel"). The wheel rotated when it was traversed radially by
an electric current, while between the poles of a horseshoe magnet. This
device is also a DC motor and is homopolar (but not acyclic.) Shown
is a model probably made for Faraday in 1823 (notice the difference in the
intersection between the wheel and the magnetic poles in Faraday's model
and that in the background sketch from Barlow.)
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1823 ~ STURGEON
produces electromagnetic rotation with a round copper disk (in action the
same as Barlow's wheel above), and which is in fact, identical to the
first "Faraday Disk" as later
used by Faraday in his investigation of electrical induction in 1831.
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1824 ~ ARAGO discovers that a rotating
non-magnetic (but electrically conductive) disk would drag a magnet around
with it. This physical phenomenon (due to what are now commonly called "eddy
currents") was then studied by Gambey,
Ampere, Poisson, Babbage
and Herschel without a resultant
explanation, because all were unaware of their (i.e., eddy currents) existence and their
mechanism of action or their cause.
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1825 ~ ELECTROMAGNET
STURGEON constructs an electromagnet
(i.e., a helical solenoid wound on an iron core), but he used uninsulated
conductors and the magnetic field produced was weak.
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1825 ~ ELECTROMAGNETIC ROTATIONAL APPARATUS
The top picture shows a collection of experimental apparatus used by NOBILI,
which includes his version of Barlow's wheel (in that it did not use a
star-shaped wheel) and three devices for demonstrating the motion of
conductors in a magnetic field, two using mercury as the moving conductor
and one using a vertical copper conductor. The picture on the bottom left shows
an electromagnetic rotation apparatus for interaction with the magnetic
field of a coil and the picture on the bottom right shows an electromagnetic
rotation apparatus for interaction with the earth's magnetic field. Both
of these are circa 1868.
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1828 ~ FIRST PRACTICAL ELECTROMAGNET
HENRY produces the first practical
electromagnet (i.e., a helical solenoid wound around an iron core) by
using insulated conductors. This vastly improved upon Sturgeon, who had
produced the first electromagnet in 1825 (but had used uninsulated
conductors.) Shown here is an early horseshoe shaped electromagnet from
Faraday's laboratory.
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1831 ~ HENRY constructs a small
electromagnetic engine (i.e., the world's first "Cyclic"
motor, although it was a reciprocating "balance" beam form of
machine, rather than a rotary machine.)
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1831
~ Faraday discovers Electromagnetic
Induction and
first experiments with Mutual Inductance
(i.e., transformer induction) and then the
electromagnetic induction of EMF due to variational
magnetic flux) and almost reports the effect of self-inductance,
but does not. (Henry reports in 1832 on his experiments with
self-inductance in electromagnets and large iron-cored coils.) |
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1831 ~ ELECTROMAGNETIC INDUCTION (FIRST DC ELECTRIC GENERATOR & FIRST
HOMOPOLAR / ACYCLIC GENERATOR)
FARADAY in discovering and investigating electromagnetic induction, produces the world's first Electric
Generator, the "Faraday Disk".
This was the world's first continuous
uni-directional electric current generating apparatus, and was
also the world's first DC Generator
which was also homopolar in structure. Shown here first on upper the
left, is the disk as used in Faraday's laboratory. (Note: Henry is
said to have discovered electromagnetic induction independently of and
prior to Faraday, but in actuality Henry had concentrated on
self-induction because of his previous work with electromagnets and Henry
did not make his discoveries until a few months after Faraday's, nor did
Henry publish his findings until the summer of 1832.) Shown secondly on
the upper right, is a graphical depiction of the above first "Faraday
Disk" apparatus, followed thirdly on the lower left by another
depiction of Faraday's first form of disk generator (in particular,
showing the induced "eddy currents".) Faraday later revisited
his first form of disk generator using adjacent parallel magnetic poles
and investigated the electrical induction effect using disks of various
types of conductive materials, as seen fourthly on the lower right in his 1851
experimental apparatus.
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1831 ~ FARADAY constructs his second version
of a continuous uni-directional electric current generator apparatus,
which comprised a copper disk whose edges floated in mercury and which
rotated in a magnetic field. This was also homopolar in structure,
but was "acyclic in operational nature." FARADAY further constructs a third
continuous uni-directional electric current generator apparatus, which was
comprised of a copper disk rotating or co-rotating with a cylindrical magnet. This was
again homopolar in structure and acyclic in its nature of
operation. His third construct led to the famous Faraday
paradox concerning the electrodynamic interactions at
play within
homopolar / acyclic apparatus.
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1832 ~ FARADAY demonstrates a large version of
his first continuous uni-directional electric current generator apparatus,
by using the large horseshoe magnet at the Royal
Institution. (Note: This demonstration concerned a homopolar
apparatus that was "not" acyclic in its nature of operation.)
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1832 ~ LINEAR AC GENERATOR (LINEAR ALTERNATOR)
FARADAY constructs the world's first alternating
current electric generator apparatus (i.e., alternator),
one which converts the input of mechanical energy into electricity by
using linearly reciprocating permanent
magnetic poles and stationary induction coils.
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1832 ~ ROTARY AC GENERATOR (ROTARY ALTERNATOR)
PIXII and DAL NEGRO
both construct alternating current (AC)
electrical generator apparatus as per Faraday's discoveries, but both use rotating
permanent magnetic poles.
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1832 ~ ROTARY DC GENERATOR (COMMUTATED DC GENERATOR)
PIXII constructs the world's first pulsating
direct-current electric generator, one which uses rotating
permanent magnetic poles with stationary induction coils and an electrical
switching or commutation mechanism called a
commutator for converting (i.e., rectifying)
the induced alternating current to direct-current (DC.) Shown on the left is Pixii's 1832 commutated
DC generator and on the right is another view. (Note: Ampere
suggested the use of such a switching mechanism to Pixii.)
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1832 ~ ROTARY DC MOTOR (COMMUTATED DC
MOTOR)
RITCHIE constructs a small electromagnetic
engine, the first commutated rotary DC motor, two different versions of which are shown here.
(Note: One can see that this motor is almost a reciprocal
form of Pixii's generator, but with moving coils and stationary permanent
magnet poles.)
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1833 ~ SAXTON
builds a commutated DC generator. |
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1834 ~ CLARKE builds a version of
Pixii's generator, an 1871 reproduction is shown here.
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1835 ~ PAGE builds
his first commutated DC generator. |
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1836 ~ STOEHRER
constructs his first generator.
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1838 ~ JACOBI
constructs the world's first electrically propelled boat (using a large
battery bank and a reciprocating solenoidal electromagnetic engine of about 1 hp) and publicly demonstrates it on the
river Neva in Russia.
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1838 ~ LINEAR RECIPROCATING DC ELECTRIC MOTOR
PAGE designs and constructs various electromagnetic engines using
reciprocating iron plungers and solenoid coil arrangements (this is
similar to Henry's engine from 1831.) Shown first is a diagrammatic
drawing of one of Page's solenoid motors. The second picture shows a full
version of Page's motor and the third picture shows a reproduction from
1858.
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1840 ~ DC MOTOR WITH A PERMANENT MAGNET ROTOR
FROMENT constructs an interesting motor, in
structure and function almost like current Permanent
Magnet Brushless motors (i.e., having a rotor
with multiple salient poles and a
commutated stator.)
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1842 ~ DAVIS appears
to have been the first to recognize (more than twenty years before anyone
else, i.e., Pacinotti in 1864 or Gramme in 1873) that the
electromechanical action of an electric motor is the inverse of that of
the electric generator.
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1850+ ~ NOLLET (with van
Malderen's help) develops several high-current generators that were
(incredibly!) used for the electrolysis (dissociation) of water in order to
provide an H2 & O2 gas supply for intense gas fired luminaires
(using limelight wicks/blocks.) After Nollet's death (1853), the Alliance
Company, with the help of Wilde and Holmes
and under Faraday's supervision,
modified and commercialized these generators for use in powering carbon
arc-lights for the production of illuminant flux. These lighting systems were employed in several European lighthouse
installations (South Foreland in 1858, Dungeness in 1862 and La Heve in
1863.) They were also used to light the construction of the Cherbourg
Docks and onboard ships such as the Lafayette and the Jerome Napoleon.
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1856 ~ SIEMENS invents
the shuttle wound (T-anchor) form of armature. A double armature machine is shown
here.
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1860 ~ RING WOUND ARMATURE
PACINOTTI invents and develops the ring
wound form of armature winding and produces both a surface
winding and slotted winding of that
type. By 1864 Pacinotti already knew of and had demonstrated, generator
and motor reciprocity (i.e., reversibility of their action) using his
particular apparatus. (Note: Both Foucalt
and de Romilly
are said to have helped Pacinotti with his development of the ring
winding.) By 1867, Pacinotti had also proposed the long distance
transmission of DC power between generators and motors.
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1863 ~ GRAMME produces
(for laboratory use) a form of Pacinotti's ring wound generator.
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1866 ~ WILDE creates a
powerful generator using field electromagnets energized by a small secondary
generator of the Siemens shuttle type. |
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1866 ~ DYNAMO PRINCIPLE
SIEMENS, Varley,
Wheatstone and Wilde (and actually preceded in 1865 by Farmer)
simultaneously invent the field self-energizing dynamo
(eliminating the need for permanent magnet field structures or a secondary
field excitation generator.)
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1867 ~ SIEMENS constructs a further form of his shuttle wound
magnetoelectric generator which finds great service in railway signalling
applications. It is also reported that with the aid of his good friend
Kirchhoff, he constructs a small unipolar,
acyclic permanent magnet
generator (picture not yet available.) |
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1870 ~ GRAMME produces another form of ring
wound generator, still using a permanent magnet field structure.
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1872 ~ DRUM WOUND ARMATURE
von HEFNER ALTENECK invents the drum
wound form of armature winding and Siemens and Halske produce the
first commercial drum wound dynamo.
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1872 ~ GRAMME and BREGUET
commence commercial production of this ring wound dynamo.
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1873 ~ GRAMME is reported to have accidentally
re-discovered? (see Davis 1842 & Pacinotti 1864) the reciprocity
between motor and generator action, at an industrial exhibition in Vienna.
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1874 ~ WESTON produces
this ring wound dynamo.
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1876 ~ ROWLAND proves
that a moving charged disk (i.e., static electricity) acted the same as do any
moving charges (i.e., convection current) in producing a magnetic field.
He thereby dispelled any doubt that there might be a difference between
"static electricity" and "current electricity." |
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1876 ~ SIEMENS constructs a low-impedance
dynamo for the electrowinning of metals.
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1876 ~ SCHUCKERT
produces his disk type (ring wound) dynamo.
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1877 ~ SIEMENS produces the type D15 dynamo,
the second dynamo (drum wound) commercially produced by Siemens and
Halske.
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1878 ~ A larger Siemens dynamo of the D15
style.
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1881 ~ SIEMENS produces this unipolar
(i.e., acyclic & homopolar) generator.
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1884 ~ SIEMENS produces the type H drum wound
dynamo.
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1884 ~ POLYPHASE AC INDUCTION MOTOR
TESLA "claims" to have built (in
late 1883)
and demonstrated (in early 1884), a two-phase rotating field
AC induction motor in Strassburg (i.e., AC polyphase
induction motor.) Tesla did not build another model of his motor
until 1887, when he filed US patents thereon after emigrating to the
United States.
(Note: the
concept of rotating fields due to polyphase currents was not new, in 1878 Gramme
produced di-phase and tri-phase alternators, and in 1879 Baily
suggested the use of rotating magnetic fields to effect the
rotation of conductors and also constructed a two-phase induction motor
that used rectangular excitation instead of sinusoidal excitation. |
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1885+ ~ The slotted form of armature
construction is slowly being adopted by manufacturers and the ring form of
winding is rapidly displaced by the drum form of winding.
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1885 ~ POLYPHASE AC INDUCTION MOTOR
FERRARIS produces and demonstrates his
first two rotating field motors for
polyphase alternating current.
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1885 ~ OERLIKON
produces this Manchester form of dynamo.
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1886 ~ FERRARIS produces his third and fourth
versions of a rotating field AC motor.
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1887 ~ EDISON produces
his distinctive (i.e., large vertical field pole) style of dynamos for DC lighting plants.
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1887 ~ TESLA builds
several models of his AC polyphase induction motor and files for patents.
(Note: He discloses his AC motor ideas to Westinghouse at this same
time.)
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1888 ~ WESTINGHOUSE
purchases all of Tesla's patent rights relating to AC polyphase motors and
to AC polyphase power distribution. The Westinghouse company then goes on
to develop the commercial AC induction motor. Tesla acts as a consultant
to the company until the end of 1889, attempting to develop a single- or
split-phase AC induction motor.
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1889 ~ GANZ produces
this alternator.
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1889 ~ A SIEMENS alternator with attached DC
excitation dynamo.
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1889 ~ TESLA patents a unipolar
(i.e., homopolar / acyclic) DC generator employing a series connection
between two induction cylinders (in
this case, a conductive belt between the two cylinders) for
EMF summation.
(Note: US Patent No. 406,968) |
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1889 ~ AC SQUIRREL CAGE INDUCTION MOTOR
Dolivo-Dobrowolski (chief electrical
engineer of AEG) invents the alternating
current squirrel-cage induction motor.
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1893 ~ BROWN produces
this AC motor of essentially modern form.
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1894 ~ BROWN produces this
large 3 phase alternator.
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1897 ~ A large SIEMENS dynamo (with the
commutator on the periphery of a large diameter, shallow armature.)
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1898 ~ SEI produces
this DC motor of essentially modern form.
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1907 ~ SERIES CONNECTED DISK TYPE HOMOPOLAR
GENERATOR
NOEGERRATH
investigates acyclic machinery and constructs a series connected (via
multiple slip rings) machine rated at 500 V @ 600 A (300 kW.)
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1912 ~ LAMME at
Westinghouse, designs and produces a 2000 kW acyclic generator (260 V @
7.6 kA.)
employing multiple series connections for EMF summation.
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1930 ~ CYLINDRICAL HOMOPOLAR GENERATOR
POIRSON develops the cylindrical form of
acyclic / homopolar generator and constructs a machine for the Paris
Exhibition rated at 14 V @ 50 kA (i.e., 700 kW.)
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1947 ~ LINEAR SYNCHRONOUS MOTOR
LAITHWAITE develops the Linear
Synchronous Motor (LSM).
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1956 ~ FAULHABER
invents the diagonally wound basket (i.e., rhombic) form of armature
winding (used for ironless armatures.)
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1964 ~ GENERAL ELECTRIC
produces an acyclic generator rated at 67 V @ 150 kA (i.e., 10 MW) for
naval propulsion research.
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1972 ~ UNIVERSITY OF TEXAS AT AUSTIN CENTER FOR
ELECTROMECHANICS (CEM) & PARKER
KINETIC DESIGN construct a homopolar generator rated at 7 V @ 14
kA (0.5 MJ.)
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1974 ~ UNIVERSITY OF TEXAS AT AUSTIN (CEM) &
PKD develops a homopolar generator rated at 42 V @ 560 kA (5 MJ.)
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1975 ~ First permanent magnet DC motor using SmCo
field magnets.
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1982 ~ FAULHABER invents statically controlled
electronic commutation for small DC motors employing ironless armatures.
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1982 ~ UNIVERSITY OF TEXAS AT AUSTIN (CEM) &
PKD produce a homopolar generator rated at 6.2 MJ (50 V @ 1 MA.)
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1986 ~ UNIVERSITY OF TEXAS AT AUSTIN (CEM) &
PKD develop a homopolar generator rated at 10 MJ (100 V @ 1.5 MA.)
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1986 ~ UNIVERSITY OF TEXAS AT AUSTIN (CEM) &
PKD construct a homopolar generator array rated at 60 MJ.
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1987 ~ ANTONELLO
invents dynamically controlled electronic commutation for small DC motors.
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1987 ~ KIESEWETTER
invents the magnetostrictive motor.
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1987 ~ First permanent magnet DC motor using NdFeB
field magnets.
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1990 ~ Fan & Tai develop the silicon
micromotor.
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1990 ~ Roberts et. al. obtain a patent on a
homopolar “Tether Power Generator For Earth Orbiting Satellites.”
(US Patent # 4,923,151)
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1994 ~ Precise Power Co.
introduces the Written Pole Synchronous Motor. |
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1996 ~ EMBEDDED ELECTRONIC COMMUTATION FOR DC
MACHINES
BLUM invents and develops
intelligent autonomous embedded electronic commutation (ECE.)
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1997 ~ BATH UNIVERSITY
develops novel heteropolar (upper picture) and homopolar (lower picture)
alternator topologies.
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1998 ~ BRANDENBURG UNIVERSITY
AT COTTBUS develops high power density axial-flux excited
alternators using permanent magnets.
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