IEEE Power & Energy Magazine - July/August 2021 - 90

of their original engineers, but this
growth in load came at an increase in
the level of short circuit destructiveness.
The 1901 AIEE Transactions paper
" Performance of an Artificial Forty-Mile
Transmission Line " by W.S.
Aldrich and G.W. Redfield described
a full-scale experimental transmission
line at the University of Illinois built
to study these conditions. The need to
build a line of this size to study faults is
an indication of how serious the analysis
situation had become.
In 1919, Westinghouse constructed
a miniature short circuit calculation
network. This helped some, but by 1920,
the large isolated systems of the first
two decades of the 20th century were
on the verge of being interconnected.
What had become a laborious calculation
of system currents and voltages
under steady-state conditions became
virtually impossible when faults and
transients were concerned. Over the
next 15 years, the situation would only
get worse.
Charles Fortescue published his
paper " Method of Symmetrical Coordinates
Applied to the Solution of
Polyphase Networks " in June 1918 in
AIEE Transactions. Now, calculating a
short circuit current was possible, but
it was still not an easy task. In this 89page
paper, he described a method of
solving an imbalanced polyphase system
using three balanced systems, but
that was not quite the technique used
today when employing symmetrical
components. That method evolved to
more practical use when Charles F.
Wagner and Robert Evans published
their book Symmetrical Components
in 1933 and when Edith Clarke
published her book Circuit Analysis
of AC Power in 1941. Since then,
others have developed methods to
further simplify these calculations,
culminating in modern computer programs,
which have put this sort of
computation on the desktops of today's
power engineers.
figure 3. The short circuit curves for an oil breaker on an inductive load showing
electromotive force (E.M.F.). (Source: K.C. Randall, " Notes on Arc Phenomena
and Tendencies in Design, " AIEE Transactions, vol. 34, part 1, p. 252, 1915.)
Generating Capacity
According to the U.S. Census in 1907,
the generating station output capacity
more than doubled in five years, going
from 1,212 MW in 1902 to 2,709 MW
in 1907. This output had reached
5,000 MW by 1912, as reported in
the U.S. census that year, with the accompanying
increase in the available
short circuit current. Edwin W. Rice,
who was to become president of General
Electric, wrote in 1901 in an AIEE
Transactions paper,
The enormous increase in the
use of electricity ... has necessitated
important changes in our
generating stations ... in the size
of machinery and electrical potentials
employed. However, a
number of machines of large size
were placed in operation with
comparatively inadequate methods
of switching and control.
Rice was referring to his design
(a)
(b)
figure 4. A (a) schematic and (b) illustration of an early dc circuit breaker.
(Source: Electric Lighting and Railways, International Textbook Company,
sec. 17, pp. 29-31, 1901.)
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ieee power & energy magazine
of the Metropolitan Traction Company's
96th Street station, which came
online in 1899. As a solution to the
problem, GE developed the H-form
oil switch, but this would prove to
be inadequate almost as soon as it
was installed.
A.R. Cheney, a West inghouse
engineer, stated in 1910 in an AIEE
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