IEEE Power & Energy Magazine - January/February 2018 - 64

system, that at one time caused the
constant-current dc system to be considered (but not seriously) as a means
for transmitting power from Niagara
Falls to buffalo.
Probably a greater drawback to the
constant-current system was that the
only motor that could be used was a
constant-current series motor. a series
constant-current motor can only produce a constant torque, meaning that
the mechanical load determined the
motor speed. the more load, the slower
the speed. this was not practical for
most machines that expected an electric motor to act like a steam engine
with a governor-the speed was more
or less constant as the mechanical load
changed. typically, lighting installations wanted to add motors because
they could then supply power to fac-

tories during the day and street lights
at night. they didn't want to replace
the constant-current lighting systems in
which they already had already invested
a great amount of money. there were literally dozens of patents to allow constant current series motors to operate
at constant speed on series arc lighting
systems. None were practical.
as electric street railways began
to proliferate about a decade after arc
lighting systems, these street railway
powerhouses, using constant potential
generators, were the ones that supplied
power to the constant-potential, constant-speed motors that would eventually replace the steam engine. by
that time, a well-developed electrical
manufacturing industry was in place,
thanks largely to the large market for
arc lamps.

For Further Reading
"arc lighting" in Electric Lighting and
Railways. Scranton, Pa: ICS, 1901, pp.
18:1-96, 19:1-59.
h. Schroeder, History of Electric
Light. Washington, DC: Smithsonian
Institution, 1923.
F. b. Crocker, "electric motor regulation," AIEE Trans., pp. 237-263, may
22, 1889.
W. P. hurley, "the series system of
street lighting distribution," AIEE Trans.,
pp. 1-32, Jan. 9, 1920.
h. C. Passer, The Electrical Manufacturers. Cambridge, ma: harvard univ.
Press, 1953.
J. Jonnes, Empires of Light. New York:
random house, 2003.
p&e

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Digital Object Identifier 10.1109/MPE.2017.2780292

ieee power & energy magazine

january/february 2018

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Table of Contents for the Digital Edition of IEEE Power & Energy Magazine - January/February 2018