Re: [NSW] Granville question re signals

[signal_spotter@my-deja.com]

In article <39CB47C5.7841BA77@ozemail.com.au>,
  trainman@ozemail.com.au wrote:
> signal_spotter@my-deja.com wrote:
>
> > Possibly because the DR relay (the one that drives the top green)
cuts
> > the low speed circuit. So by the time it's cut the LSp and then
makes
> > up the contact to light the top green is the possible reason for the
> > delay. I'm only guessing here.
>
> I think it is to do with proving the trip has lowered before clearing
the top
> green.  Why can't they prove the trip has lowered, then cut the
bottom green and
> turn the top green on simultaneously?
>
> --
> 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.
>
>
Because you need a function to drive the trip (HR relay) and since that
is the last function in the process, the trip can only be detected in
the outgoing signal operating circuit. But without the circuits (or
specific signal numbers) I'm only guessing.

regards Ian
Signal Design Engineer




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