Re: High-voltage track circuits

[craigd@lios.apana.org.au (C. Dewick)]

In <Sjda4.3915$oJ5.9153@newsfeeds.bigpond.com> "Ronald BESDANSKY" <ronbest@bigpond.com> writes:

>An experiment was carried out about 30 years ago on the NSW National Park
>line, using short pulses of about 100 volts instead of continuous DC or
>low-frequency AC to feed track circuits. Does anybody remember this
>experiment, and was it successful?

You are probably referring to Jeumont-Schneider track circuits, which use a
pulsed signal swinging to about 100 volts positive and back to about 20
volts negative in each cycle (the period is about 1/2 a second). I've got a
book about these from when I was working in Signal Branch in the late
1980's, and one day I'll scan in some of the pages...

J/S track circuit are in use in lots of places, but the location remember in
particular is Port Kembla Inner Harbour (which I had a hand in doing much of
the track circuit commissioning for) where they were used specifically
because of the coal and grain dust from the coal and grain unloaders, as
well as rusting of the steel due to proximity to the sea water, and other
types of noxious problems which could cause conventional AC or even
audio-frequency track circuits like the CSEE and ML types, to fail and be
unreliable.

Actually, Mortdale yard (the new signalling) has J/S track circuits I think,
as did Glenlee coal prep siding. I'm sure other people will tell us other
places where they are used.

Regards,

Craig.
-- 
            Craig Ian Dewick            |       Stand clear - jaws closing
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