IEEE Power & Energy Magazine - March/April 2016 - 87

figure 3. A drawing for the Sprague electro dynamic motor
patent U.S. Patent 295,454, issued to Sprague on 18 March
1884. (Photo courtesy of John L. Sprague.)

developed the first dynamo, where one
or more wire coils rotating in a magnetic
field created an alternating electric current in each one. When the ends of the
coils were connected to terminals, electrical circuits could be designed such
that a direct current was created. Rapidly
improved upon by scientists around the
world, in 1870 Belgium-born Frenchman Zénobie T. Gramme demonstrated
the first truly practical continuous current self-exciting dynamo-electric machine. Then in 1873 at the Munich Exhibition, Gramme and Hippolyte Fontaine
of France stunned the rest of the world
by jointly demonstrating what was
called "reversibility of function." Using
one dynamo to generate electricity and
a second one to transform this electricity back into mechanical power, they
laid the foundation for all modern electric power transmission.
86

ieee power & energy magazine

figure 4. The first page of the Sprague regulator for electrodynamic motors patent, U.S. patent 313,247, issued to Sprague
on 3 March 1885. (Image courtesy of John L. Sprague.)

Now there was a practical replacement for storage batteries, and only 42
years after Faraday's initial observation, an explosion of activity to improve control of motors and dynamos
began, including Sprague's inverted
dynamo design. Surprisingly, while
nine years later at the 1882 London
Crystal Palace Electrical Exposition
there were numerous exhibits of different power-generating dynamos,
there were still no practical electric
motors. This was because up to that
point none could maintain constant
power under a changing load. An electric motor-driven railway engine pulling a load up a hill slowed down while
just the reverse occurred on a downgrade. While this was impractical,
it could become exciting, especially
down a steep grade. Sprague and others were about to change this.

The Self-Regulating
Nonsparking dc
Electric Motor
The dc electric motor field that Sprague
and SERM were entering in the early
1880s was already crowded, with major players such as Edison, Siemens,
Esmond, and Deprez. Former furniture
manufacturer Thomas J. Van Depoele
was especially prolific with some 243
issued patents between 1881 and 1894,
with the majority covering inventions
in electric motors and electric railway
transportation. It is impossible to directly compare all the competitive patent claims with those of Sprague since
many are almost identical. However, the
patent content is dramatically different.
As we shall see, rather than hide exactly
how his motors worked, in many of his
patents Sprague reveled in supplying
detailed information that he referred
march/april 2016



Table of Contents for the Digital Edition of IEEE Power & Energy Magazine - March/April 2016

IEEE Power & Energy Magazine - March/April 2016 - Cover1
IEEE Power & Energy Magazine - March/April 2016 - Cover2
IEEE Power & Energy Magazine - March/April 2016 - 1
IEEE Power & Energy Magazine - March/April 2016 - 2
IEEE Power & Energy Magazine - March/April 2016 - 3
IEEE Power & Energy Magazine - March/April 2016 - 4
IEEE Power & Energy Magazine - March/April 2016 - 5
IEEE Power & Energy Magazine - March/April 2016 - 6
IEEE Power & Energy Magazine - March/April 2016 - 7
IEEE Power & Energy Magazine - March/April 2016 - 8
IEEE Power & Energy Magazine - March/April 2016 - 9
IEEE Power & Energy Magazine - March/April 2016 - 10
IEEE Power & Energy Magazine - March/April 2016 - 11
IEEE Power & Energy Magazine - March/April 2016 - 12
IEEE Power & Energy Magazine - March/April 2016 - 13
IEEE Power & Energy Magazine - March/April 2016 - 14
IEEE Power & Energy Magazine - March/April 2016 - 15
IEEE Power & Energy Magazine - March/April 2016 - 16
IEEE Power & Energy Magazine - March/April 2016 - 17
IEEE Power & Energy Magazine - March/April 2016 - 18
IEEE Power & Energy Magazine - March/April 2016 - 19
IEEE Power & Energy Magazine - March/April 2016 - 20
IEEE Power & Energy Magazine - March/April 2016 - 21
IEEE Power & Energy Magazine - March/April 2016 - 22
IEEE Power & Energy Magazine - March/April 2016 - 23
IEEE Power & Energy Magazine - March/April 2016 - 24
IEEE Power & Energy Magazine - March/April 2016 - 25
IEEE Power & Energy Magazine - March/April 2016 - 26
IEEE Power & Energy Magazine - March/April 2016 - 27
IEEE Power & Energy Magazine - March/April 2016 - 28
IEEE Power & Energy Magazine - March/April 2016 - 29
IEEE Power & Energy Magazine - March/April 2016 - 30
IEEE Power & Energy Magazine - March/April 2016 - 31
IEEE Power & Energy Magazine - March/April 2016 - 32
IEEE Power & Energy Magazine - March/April 2016 - 33
IEEE Power & Energy Magazine - March/April 2016 - 34
IEEE Power & Energy Magazine - March/April 2016 - 35
IEEE Power & Energy Magazine - March/April 2016 - 36
IEEE Power & Energy Magazine - March/April 2016 - 37
IEEE Power & Energy Magazine - March/April 2016 - 38
IEEE Power & Energy Magazine - March/April 2016 - 39
IEEE Power & Energy Magazine - March/April 2016 - 40
IEEE Power & Energy Magazine - March/April 2016 - 41
IEEE Power & Energy Magazine - March/April 2016 - 42
IEEE Power & Energy Magazine - March/April 2016 - 43
IEEE Power & Energy Magazine - March/April 2016 - 44
IEEE Power & Energy Magazine - March/April 2016 - 45
IEEE Power & Energy Magazine - March/April 2016 - 46
IEEE Power & Energy Magazine - March/April 2016 - 47
IEEE Power & Energy Magazine - March/April 2016 - 48
IEEE Power & Energy Magazine - March/April 2016 - 49
IEEE Power & Energy Magazine - March/April 2016 - 50
IEEE Power & Energy Magazine - March/April 2016 - 51
IEEE Power & Energy Magazine - March/April 2016 - 52
IEEE Power & Energy Magazine - March/April 2016 - 53
IEEE Power & Energy Magazine - March/April 2016 - 54
IEEE Power & Energy Magazine - March/April 2016 - 55
IEEE Power & Energy Magazine - March/April 2016 - 56
IEEE Power & Energy Magazine - March/April 2016 - 57
IEEE Power & Energy Magazine - March/April 2016 - 58
IEEE Power & Energy Magazine - March/April 2016 - 59
IEEE Power & Energy Magazine - March/April 2016 - 60
IEEE Power & Energy Magazine - March/April 2016 - 61
IEEE Power & Energy Magazine - March/April 2016 - 62
IEEE Power & Energy Magazine - March/April 2016 - 63
IEEE Power & Energy Magazine - March/April 2016 - 64
IEEE Power & Energy Magazine - March/April 2016 - 65
IEEE Power & Energy Magazine - March/April 2016 - 66
IEEE Power & Energy Magazine - March/April 2016 - 67
IEEE Power & Energy Magazine - March/April 2016 - 68
IEEE Power & Energy Magazine - March/April 2016 - 69
IEEE Power & Energy Magazine - March/April 2016 - 70
IEEE Power & Energy Magazine - March/April 2016 - 71
IEEE Power & Energy Magazine - March/April 2016 - 72
IEEE Power & Energy Magazine - March/April 2016 - 73
IEEE Power & Energy Magazine - March/April 2016 - 74
IEEE Power & Energy Magazine - March/April 2016 - 75
IEEE Power & Energy Magazine - March/April 2016 - 76
IEEE Power & Energy Magazine - March/April 2016 - 77
IEEE Power & Energy Magazine - March/April 2016 - 78
IEEE Power & Energy Magazine - March/April 2016 - 79
IEEE Power & Energy Magazine - March/April 2016 - 80
IEEE Power & Energy Magazine - March/April 2016 - 81
IEEE Power & Energy Magazine - March/April 2016 - 82
IEEE Power & Energy Magazine - March/April 2016 - 83
IEEE Power & Energy Magazine - March/April 2016 - 84
IEEE Power & Energy Magazine - March/April 2016 - 85
IEEE Power & Energy Magazine - March/April 2016 - 86
IEEE Power & Energy Magazine - March/April 2016 - 87
IEEE Power & Energy Magazine - March/April 2016 - 88
IEEE Power & Energy Magazine - March/April 2016 - 89
IEEE Power & Energy Magazine - March/April 2016 - 90
IEEE Power & Energy Magazine - March/April 2016 - 91
IEEE Power & Energy Magazine - March/April 2016 - 92
IEEE Power & Energy Magazine - March/April 2016 - 93
IEEE Power & Energy Magazine - March/April 2016 - 94
IEEE Power & Energy Magazine - March/April 2016 - 95
IEEE Power & Energy Magazine - March/April 2016 - 96
IEEE Power & Energy Magazine - March/April 2016 - 97
IEEE Power & Energy Magazine - March/April 2016 - 98
IEEE Power & Energy Magazine - March/April 2016 - 99
IEEE Power & Energy Magazine - March/April 2016 - 100
IEEE Power & Energy Magazine - March/April 2016 - 101
IEEE Power & Energy Magazine - March/April 2016 - 102
IEEE Power & Energy Magazine - March/April 2016 - 103
IEEE Power & Energy Magazine - March/April 2016 - 104
IEEE Power & Energy Magazine - March/April 2016 - 105
IEEE Power & Energy Magazine - March/April 2016 - 106
IEEE Power & Energy Magazine - March/April 2016 - 107
IEEE Power & Energy Magazine - March/April 2016 - 108
IEEE Power & Energy Magazine - March/April 2016 - 109
IEEE Power & Energy Magazine - March/April 2016 - 110
IEEE Power & Energy Magazine - March/April 2016 - 111
IEEE Power & Energy Magazine - March/April 2016 - 112
IEEE Power & Energy Magazine - March/April 2016 - 113
IEEE Power & Energy Magazine - March/April 2016 - 114
IEEE Power & Energy Magazine - March/April 2016 - Cover3
IEEE Power & Energy Magazine - March/April 2016 - Cover4
https://www.nxtbook.com/nxtbooks/pes/powerenergy_091020
https://www.nxtbook.com/nxtbooks/pes/powerenergy_070820
https://www.nxtbook.com/nxtbooks/pes/powerenergy_050620
https://www.nxtbook.com/nxtbooks/pes/powerenergy_030420
https://www.nxtbook.com/nxtbooks/pes/powerenergy_010220
https://www.nxtbook.com/nxtbooks/pes/powerenergy_111219
https://www.nxtbook.com/nxtbooks/pes/powerenergy_091019
https://www.nxtbook.com/nxtbooks/pes/powerenergy_070819
https://www.nxtbook.com/nxtbooks/pes/powerenergy_050619
https://www.nxtbook.com/nxtbooks/pes/powerenergy_030419
https://www.nxtbook.com/nxtbooks/pes/powerenergy_010219
https://www.nxtbook.com/nxtbooks/pes/powerenergy_111218
https://www.nxtbook.com/nxtbooks/pes/powerenergy_091018
https://www.nxtbook.com/nxtbooks/pes/powerenergy_070818
https://www.nxtbook.com/nxtbooks/pes/powerenergy_050618
https://www.nxtbook.com/nxtbooks/pes/powerenergy_030418
https://www.nxtbook.com/nxtbooks/pes/powerenergy_010218
https://www.nxtbook.com/nxtbooks/pes/powerenergy_111217
https://www.nxtbook.com/nxtbooks/pes/powerenergy_091017
https://www.nxtbook.com/nxtbooks/pes/powerenergy_070817
https://www.nxtbook.com/nxtbooks/pes/powerenergy_050617
https://www.nxtbook.com/nxtbooks/pes/powerenergy_030417
https://www.nxtbook.com/nxtbooks/pes/powerenergy_010217
https://www.nxtbook.com/nxtbooks/pes/powerenergy_111216
https://www.nxtbook.com/nxtbooks/pes/powerenergy_091016
https://www.nxtbook.com/nxtbooks/pes/powerenergy_070816
https://www.nxtbook.com/nxtbooks/pes/powerenergy_050616
https://www.nxtbook.com/nxtbooks/pes/powerenergy_030416
https://www.nxtbook.com/nxtbooks/pes/powerenergy_010216
https://www.nxtbook.com/nxtbooks/ieee/powerenergy_010216
https://www.nxtbook.com/nxtbooks/pes/powerenergy_111215
https://www.nxtbook.com/nxtbooks/pes/powerenergy_091015
https://www.nxtbook.com/nxtbooks/pes/powerenergy_070815
https://www.nxtbook.com/nxtbooks/pes/powerenergy_050615
https://www.nxtbook.com/nxtbooks/pes/powerenergy_030415
https://www.nxtbook.com/nxtbooks/pes/powerenergy_010215
https://www.nxtbook.com/nxtbooks/pes/powerenergy_111214
https://www.nxtbook.com/nxtbooks/pes/powerenergy_091014
https://www.nxtbook.com/nxtbooks/pes/powerenergy_070814
https://www.nxtbook.com/nxtbooks/pes/powerenergy_050614
https://www.nxtbook.com/nxtbooks/pes/powerenergy_030414
https://www.nxtbook.com/nxtbooks/pes/powerenergy_010214
https://www.nxtbookmedia.com