Re: Overhead power lines

[David Johnson <trainman@ozemail.com.au>]

Lourie Smit wrote:

> The following question appeared on the Australia Transport Discussion Board
> (English Version). As there do not appear to be too many railway people
> looking at that, I thought I would repeat it here. It was posted by Andrew
> on Saturday 29/1/2000.
>
> "Why do some parts of the cityrail network have only one wire touching the
> pantograph on the train and some parts have two.?"

Better contact between the train and the overhead wire.  It is more of an issue
with electric locomotives which can pull 800 amps through one pantograph.
Pantographs these days have two carbon strips, and most overhead has two contact
wires.  This gives four points of contact, meaning a quarter of the current
through each point, reducing heat and wear and tear.  It also will halve the
lift force at any one point.  It is also cheaper to have two smaller diameter
wires than one large diameter wire.


--
David Johnson
trainman@ozemail.com.au
http://www.ozemail.com.au/~trainman/
------------------------------------
These comments are made in a private
capacity and do not represent the
official view of State Rail.
C.O.W.S. Page 11.