Today I visited the Elfun Hall of History at the Schenectady Museum. They
have all (over a million) GE negatives taken over the past century. They had
external and internal pictures of the Inghams Mills Hydroelectric plant taken in
1912 when the plant was built. Apparently it had all GE machinery. In addition
to the two main turbine driven generators there was also a frequency changing
motor-generator set. While the ratings of this M-G set were not given, it looked
to be big enough to serve the whole FJ&G load.
I believe that this is circumstantial evidence enough to say that the
Inghams Mill Hydroelectric Plant supplied 25 cycles per second AC power to the
FJ&G to run their AC to DC converters. The 1903 FJ&G Tribes Hill steam
powered 25 cycles per second plant could then be put on standby service to serve
the railroad only when Inghams had insufficient water (typically in the fall of
the year) or needed maintenance. This probably saved the railroad a lot of
In 1931-1932, new 60 cycles per second automatic substations were installed
on the FJ&G and the old 25 CPS equipment was retired. 60 CPS power could
then be purchased from the power company grid which was then in
existence. Thereafter, Tribes Hill 25 CPS generated power could not be
used, even on a standby basic, but the utility grid was then highly reliable (a
large steam generating plant was then in service, on the Mohawk, just below
Amsterdam) and there were a mutiplicity of large hydroelectric
plants operating on the grid.
I am still looking for the exact rating of the frequency changing M-G set
installed at Inghams in 1912. Can anyone of you help with this?