18 Feb
2007
18 Feb
'07
10:46 p.m.
Bob Bradlee wrote:
On Sat, 17 Feb 2007 20:48:33 -0800, Brent Hilpert wrote:
Came across the following while searching for info on 25Hz systems:
http://www.nycsubway.org/tech/power/rotary.html
http://www.nycsubway.org/tech/power/
Nice writeups about the NYC subway and it's power systems. The trains ran on
DC but the power transmission was AC. It suggests there were some benefits of
the lower frequency for the rotary-mechanical AC->DC conversion process.
Apparently some of the 25Hz stuff was still in use into the mid-1990s.
.. To make this mildly on-topic, those of us here can all take offense at the
following quote:
"In even later years, solid-state rectifiers of sufficient capacity for the
traction power industry were developed, and substations became no more
exciting than giant computer chips."
Chuck Guzis wrote:
> coke-oven (producer) gas. For some reason never made clear to me,
> one of the competing "standards" for AC distribution was 25Hz (both
> 50 and 110v).
Didn't the 25 Hz stuff have it's origins
in turn-of-the-century
electric-train/streetcar technology? ..such established systems then being
extended into residential/industrial use in some areas. There were a few
30's-era radios made for 25Hz, distinguished by their oversize power transformers.
I remember commenting about the lightbulbs flickering in the NY subway and my dad
tellling me that the
subway operated on 25 cycle. this was close to 50 years ago. I asume it has been upgraded
by now.
Bob