IEEE Power & Energy Magazine - May/June 2019 - 8

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The History of
Polyphase Power
It was a great pleasure to read Joseph J.
Cunningham's article, "89 Liberty Street:
The Birthplace of Commercial Polyphase Power" [1]. It provided a fascinating description of Nikola Tesla's 1887
site of activity, in New York City, where
the outstanding pioneer perfected his first
practical induction motor and ac systems
with more than one single phase.
The author clearly pays tribute to Tesla's polyphase solutions for two-phase
motors and generators, which were presented in 1888 (see Figures 3-5 in "Figure Captions") and also expresses Tesla's
vision of a concept for a three-phase
system (Figure 6 in "Figure Captions").
In the caption for this figure, Cunningham states: "This three-phase concept
was a harbinger of the future trend
and eventual dominance of three-phase
systems." This brings to mind significant contributions of other pioneers of
the time, as discussed in my "History"
article about early three-phase power,
published in the September 2007 issue
of this magazine [5].
The German engineer Friedrich August Haselwander had already built the
Digital Object Identifier 10.1109/MPE.2019.2896688
Date of publication: 17 April 2019

ieee power & energy magazine

figure 1. The three-phase synchronous generator built by Haselwander,
1887 [5]. (Photo courtesy of Deutsches
Museum, Munich.)

first three-phase synchronous generator
(Figure 1) in 1887. Soon after, in 1888,
Haselwander set a distinctive mark for a
three-phase power transmission system.
It comprised a synchronous generator,
a synchronous motor, step-up and stepdown transformers, and the interconnecting transmission leads (Figure 2).
The power transmission was achieved

with only three wires, whereas Tesla assumed that six wires were necessary.
Somewhat later, on 13 April 1891,
a retrospective view was given on this
subject at a meeting of the German
Electrical Society. One of the speakers,
the prominent Wilhelm Lahmeyer, concluded that "the invention of a long-distance transmission system might truly
be credited to two persons only: Tesla
and Haselwander. ... The practical importance of Haselwander's system, in
contrast to that of Tesla, is, in short, that
the first mentioned achieves the same
result with three wires compared to the
six needed for the latter." (See [4].) He
might have been thinking, primarily,
of the markedly different needs in both
space and copper for transmission lines.
The key reason for the lower number of connections is the interlinkage
within the higher-class three-phase system, invented in the late 1880s. When
describing the main progresses as demonstrated at the 1891 International Electrical

figure 2. The three-phase transmission system according to Haselwander,
1888, with the generator, step-up transformer, transmission line, step-down
transformer, and drive motor (from a patent application) [5].
may/june 2019

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