TELECOM Digest OnLine - Sorted: 25 Hz Power -- But Wait, There's More !!

25 Hz Power -- But Wait, There's More !!

jsw (
Thu, 9 Mar 2006 10:45:08 CST

Curiosity got me last night, and I googled a bit for references to
commercial 25Hz power, and I found this tidbit buried in a railfan
newsletter pertaining to the Pennyslvania Railroad and Penn Station in

"Up until the late 1970's, at least, Consolidated Edison still
supplied power billable at their meter, depending on your location in
NYC, at DC, 25 Hertz and 60 Hertz, in a variety of voltages. ...

At the turn of the {last} century {and} well until the 1940's both DC
and 25 Hertz were fairly widely used as power for commercial
establishments; after all, Edison started the city off with a DC
system. ...

The PRR had a 25 Hertz power supply feed account established with
Consolidated Edison in the 1930's when they strung catenary into NYC.
The interesting thing is that this was supplied and billed by Edison
to the PRR at catenary voltage (11 kV at 25 Hertz), and not at 132 kV
as done by the PRR's other 25 Hertz suppliers ...

The Consolidated Edison 25 Hertz supply generally was the highest cost
power to the railroad, even well into the Amtrak era, ..."

I knew that DC was commercially available in places in Manhattan in
most of the 20th century, but it's news to me that commercial 25Hz was
available in the area.

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