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Overhead Neutral Sections

Discussion in 'General Discussion' started by esgtee, Oct 14, 2020.

  1. esgtee

    esgtee New Member

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    So when sim driving through neutral sections, I power off with pantograph raised like I was trained to on the WCML. But are there different standard ways (other lines or other countries) like lowering pantographs or powering through them with some automatic power cut-off?

    guardupfront
    This sounds like a railway pub quiz question. Which station on lines out of Waterloo has 25kv ac overhead? First I was thinking Wimbledon because of Croydon Tramlink, but that is 750dc overhead. Wracking my brain, and came up with... Reading?
     
  2. guardupfront

    guardupfront Member

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    Nailed it in one!
     
  3. brummie

    brummie Member

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    I would think they would do the same. Lowering then raising a pantograph for a neutral section would take a bit of time, and at speed would need meticulous timing. Much easier just to slip controller into neutral as lm sure you would agree.
    I think powering through them may cause a slight jolt, don't know really.
     
  4. guardupfront

    guardupfront Member

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    For DC there’s no actual requirement to stop taking power over gaps, but the professional driving policies of DC TOCs (mine included) make reference to reducing power to avoid jolts and surges when your train gets back on the third rail again.
    My main AC issue is that it’s significantly harder (AFAIK) to short circuit in an emergency than DC is, but the actual driving over the two is pretty much the same
     
  5. brummie

    brummie Member

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    Interesting. I think l might try that then, reduce power setting instead of going into neutral.
     
  6. 749006

    749006 Well-Known Member

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    In the UK when you go thru a Neutral Section there are track magnets on the sleeper ends either side
    The magnets trip the Automatic Power Cutoff - APC and the main breaker then reset without any action from the driver.
    It is modelled on a few routes such as WCML over Shap where the Class 87 has to be run down before the Neutral sections

    In Europe it is all at the Drivers command -
    At some places it is just necessary to shut off and open the breaker - other places the Panto must be lowered.
     
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  7. brummie

    brummie Member

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    Hi Peter,
    Thats intetesting what you say. For simming purposes, what do you normally do when going over neutral sections, for example the class 350?
     
  8. esgtee

    esgtee New Member

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    Yeah, I'm told powering through could make a jolt, but the main reason we're told to power off is to stop any arcing from wire to pantograph. This can chip the carbon strip on the pan, or worse cause damage like an air leak (compressed air is what raises it).

    For AC there are DEPs, for Network Rail specialists to earth it (I'm told) with big long poles. Is DC with that wooden bar thing?

    Now the 87 seems really weird to me. Tapping the transformer gradually, running up, running down, stepping down. I guess that's why you have the black neutral warning board. Back then with locos took some time to shut off power, these days it's 1 second to move the power/brake controller.
     
    Last edited: Oct 15, 2020
  9. Cameron's Gaming

    Cameron's Gaming Active Member

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    Why would you need to short out OHLE in an emergency?
     
  10. esgtee

    esgtee New Member

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    If the 3rd rail is accidentally re-energised, a short circuit to the -ve return path of the DC system causes the circuit-breakers at the substation to trip immediately, protecting personnel at a worksite or emergency scene. With overhead line isolation, they switch off the current first, but there's a residual voltage to get rid of. This is earthed to the running rail via specific catenary gantries, by using giant crocodile clips held on poles :D

    If you've got an emergency, and passengers have to be evacuated, you don't want 750Vdc or for that matter 25kVac to cook your customers!!!
     
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  11. guardupfront

    guardupfront Member

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    sure is, the mighty Short Circuit Bar!

    25kV AC on a broken/dropped wire can arc up to 9 feet through the air to electrocute a person; I wouldn’t want to be doing an evacuation/examination of the line in the dark with the possibility of that happening. A poor VT crew many years back experienced that.
     
  12. 749006

    749006 Well-Known Member

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    Nothing :D
    If it is built in to the loco/unit I obviously use it but for a train without that system I don't bother.

    I have a CFR Route and I forgot about a Neutral Section and the systems said "Game Over"
    Must change that Scenario
     
  13. brummie

    brummie Member

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    I bet you were near to the end when you got the dreaded "Game Over" :D:D
     
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