Berkshire Section, Dedication: 2 October 2004
20 March 1886 William Stanley provided alternating current
electrification to offices and stores on Main Street in Great
Barrington, Massachusetts. He thus demonstrated the first practical
system for providing electrical illumination using alternating
current with transformers to adjust voltage levels of the
March 20,1886, William Stanley demonstrated the first practical
system for providing electric illumination with the use of
alternating current, and transformers to adjust the voltage levels
of the distribution system.
event took place on Main Street in Great Barrington, Massachusetts.
technique in 1886 was virtually identical to the system used for the
distribution of electric power today.
alternating current system (using transformers) eventually replaced
Thomas Edison's direct current system because of the ability to
efficiently adjust voltage levels in different parts of the system
so as to minimize the inherent power losses associated with
distribution. This was not possible in the direct current system
because transformers do not work on "D.C.".
Siemens steam engine driven alternating current generator, located
in "an old rubber mill" near Cottage Street in Great
Barrington, provided the power for Stanley's pioneering distribution
system. This power system was actually placed in operation on March
6, and the following two weeks were utilized for "research and
development" before the public demonstration.
designed and built his own transformers for this installation.
He demonstrated their ability to both raise and lower voltage
by stepping up the 500-volt output of the Siemens generator to
3000-volts, lighting a string of thirty series-connected 100-volt
incandescent lamps, and then stepping the voltage back down to
were run from his "central" generating station along Main
Street in Great Barrington, fastened to the elm trees which lined
that thoroughfare. A
total of six step-down transformers were located in the basements of
some Main Street buildings to lower the distribution to 100-volts. A
total of twenty business establishments were then lighted using
demonstration of raising the generator voltage to 3000-volts and
then back down again was exactly the same concept as employed in
present day power systems where a " generator step-up"
transformer is used to raise the system voltage to a very high level
for long distance transmission, and then "large
substation" transformers are used to lower the voltage to some
intermediate level for local distribution. The transformers located
in the basements of the buildings correspond, of course, to the
transformers now used to step voltage down to the ultimate level for
actual use by individual customers.
Stanley's installation in Great Barrington was the first such system
to include all of the basic features of large electric power systems
as they still exist over one hundred years later.
work at Great Barrington was built upon previous work by other
investigators, notably the team of Gaulard and Gibbs in England
(just as the work of Thomas Edison in regards to the development of
the first practical incandescent lamp was built upon previous
efforts by others).
however, in designing transformers for use at Great Barrington, was
the first to understand and appreciate three key features which
allowed the alternating current transformer system of electric power
distribution to be feasible:
Gaulard and Gibbs had specified that their "transformer"
devices were to be connected in series. Stanley recognized that such
devices needed to be connected in parallel so as to prevent any
changes in load on one such device from interfering with the
operation of the remaining devices.
Stanley was the first to understand sufficiently the behavior of the
magnetic "circuit" (or core) of a transformer, and the
need for this to be a closed circuit so as to allow for the
regulation of the voltage produced in the secondary winding.
Other investigators of that era were convinced of the futility of
applying several hundred volts to a coil of wire (the primary
winding of the transformer) having a resistance of less than one
ohm. Stanley, on the other hand, was able to comprehend the concept
of "counter eletromotive force" which is the means by
which current flow is limited in the transformer primary.
at Great Barrington, William Stanley first applied all of the
essential theoretical concepts necessary for the use of transformers
in the practical distribution of alternating current electric power.
Thomas J. Blalock