Re: NEWCASTLE ACCIDENT

[mpp_editor@my-dejanews.com]

In article <7476og$ia8$1@metro.ucc.usyd.edu.au>,
  matthew@mail.usyd.edu.au (Matthew Geier) wrote:
 the overhead was brought down on the train, and that it took 15
> >>minutes to get the power isolated. That seems an excessive time to have a
> >>"live" metal train! Can anyone confirm this, and explain why it took so
> >>long? I would think the scenario would be:
> >>
> >Are the bodies of the carriages insulated from the track? If not, wouldn't
> >the protection equipment on the DC power supply trip when the overhead (+)
> >touches anything at negative potential, eg train, rails etc.
>
The circuit breakers in the substation are setup to alow three resets in quick
sucesion, with each reset occuring after apporx 30 seconds after detecting a
fault. If it resets three times, the high speed circuit breaker locks itself
out, requiring manual resetting by a repesentative from elec branch.

I hope this helps

Stuart Ellis
>

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