Post by Shawn HirnIn article
Post by P***@yahoo.comHello i'm new, 15 years old and got a question. Since I was little I
have always noticed power lines on top of train tracks, what are they,
whats the point of them? Why are they always changing, into different
designs.
Some trains run off electric power and those wires you see provide that
power.
In addition to the wires needed where electric power is used to move
the trains, a good amount of railroad line right-of-way is used for
Philadelphia Electric high tension lines, often carried on the same
overhead structure which supports the railroad wiring. Look for sets
of three wires high up on the structure, with the largest sets of
insulators: these are generally the three-phase commercial power
grid lines (the very highest lines are directly connected to the
structures without insulators, and serve as lightning protection).
As for "changing, into different designs", the arrangement of
the three wires is often forced by clearance issues to keep
within the confines of the railroad property lines.
Lower down on the structure will be the feed line(s) for railroad
use, with fewer/smaller insulators. In the Philadelphia
area these will be single-phase power at 33000 or 11000 volts,
with the 33000 volt lines feeding remote transformers which
lower 33000 to the 11000 volts used by the trains. There might
also be feed lines used to power the signal system (the signal
wires are either on separate poles, or buried underground).
Lowest on the structure are the wires which actually power
the trains, suspended on often complex webs of support
wires, and collectively called catenary, from the natural curve
of a suspended wire.
Keep asking questions, if you need more information.
Best wishes.
Bruce B. Reynolds, Trailing Edge Technologies, Glenside PA