IEEE Power & Energy Magazine - July/August 2021 - 86

Robert D. Barnett
short circuit protection
challenges in the early years
D
86
DURING THE EVENING RUSH
hour of 24 July 1903, New York City's
Manhattan Elevated Railway experienced
a shutdown that began in its 74th
Street power station and quickly involved
the entire system. This station,
one of the most advanced of its time, had
been in operation for only seven months.
It contained eight 5,000-kW, threephase,
25-Hz, 11,000-V alternators driven
by reciprocating steam engines. Figure
1 shows one of these vertical steam
engines with the large-diameter multipolar
alternator attached. A frantic effort
returned operation by late evening.
However, just before midnight, another
major system fault occurred. The trains
were running again within 24 h, but the
cause of the shutdown was unknown
and resulted in much speculation in the
engineering press.
Three years after the Manhattan
episode, Chicago's Commonwealth
Edison Fisk Street plant was involved
in a major outage resulting from generator
burnouts. This was the first plant
to employ large turbo alternators. One
of these units is shown in Figure 2.
The four-pole alternator was mounted
on top of the turbine. As with the 74th
Street station, no one was certain what
caused these faults.
By 1909, seven of these Commonwealth
generators had failed similarly.
According to Schuchardt and Schweitzer
in a 1911 AIEE Transactions
paper, " ... armature end turns were
Digital Object Identifier 10.1109/MPE.2021.3073228
Date of current version: 21 June 2021
ieee power & energy magazine
In this issue's " History " column, we explore the challenges of fault protection
in the early years of electrification. Beginning in the 1890s and taking us up to
the 1920s, this article covers early protection devices, including fuses, knife
switches, circuit breakers, and the use of current-limiting reactors. The role
that early ac circuit analysis and techniques played in the overall evolution of
short circuit protection equipment is also examined.
We welcome back Robert D. Barnett for a sixth time to the " History " column
of our IEEE Power & Energy Magazine. A Life Senior Member of IEEE,
Robert graduated from the University of Waterloo and Niagara College. In
1982, he formed the Niagara Society for Industrial History as a support group
for a proposed museum in a former Niagara Falls power plant, and he has
written on the history of the topic.
John Paserba,
Associate Editor, " History "
torn loose and the windings were
pretty well wrecked. " The loss in revenue
was immense. There were several
similar but less catastrophic cases of
outages at other generating stations
where there was no obvious reason for
the shutdowns.
The best engineering talent from
major electrical manufacturers would
spend the next 20 years developing
theories and designing solutions. It was
apparent from the damage caused that
the equipment had experienced short
circuits of a magnitude never seen before.
It would eventually become apparent
that intermittent arcing ground
faults degraded the cable insulation.
The reduced reactance of the fourpole
turbo alternators had contributed
to the large short circuit current at
1540-7977/21©2021IEEE
the Fisk Street plant. However, it was
not until the end of World War I that
these issues had been brought fully under
control.
During this period, there were actually
three interrelated problems. First,
there was an evolving understanding of
ac circuit analysis. A simple means of
solving ac circuits was needed as was
a straightforward way to calculate fault
levels at any point in large interconnected
systems. The second problem
was the failure to appreciate how much
the rapid development of new interconnected
generating stations would
affect short circuit conditions. Third,
there was a poor circuit breaker design
philosophy that followed from a lack
of understanding of the dynamics of
the arc formed after the opening of the
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