Re: Impressions of the Gold Coast line

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

Chris Downs wrote:

> I thought a chopper literally chopped the current off for a short period of
> time and this was done many times per second.  More current's chopped out when
> starting giving the same effect as burning "excess" current with resistors.
> As the train accelerates the chopper stops current for shorter periods of time
> (like switching through resistors) until the point is reached where continuous
> current flows, i.e. the chopper is off.

A chopper is a Gate Turn Off Thyristor.   A normal Thyristor only turns on, then
switches off when the voltage reaches 0.  As DC doesn't turn off, the GTO
thyristor is used, which turns off when remove the voltage from the Gate.

I think that is basically accurate, correct as necessary. :)


--
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.