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Can’t understand system short

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  • Member since
    December 2015
  • From: Shenandoah Valley
  • 9,094 posts
Posted by BigDaddy on Thursday, February 22, 2018 2:39 PM

I wonder what the quarter test would do on the other 2 districts?

The PSX circuit breakers daisy chain to other PSX breakers, but I'm not sure that is electrically any different than the terminal strip.  If the main circuit breaker is defective, it could trip the other two and the command station.

Henry

COB Potomac & Northern

Shenandoah Valley

  • Member since
    December 2004
  • From: Bedford, MA, USA
  • 21,483 posts
Posted by MisterBeasley on Thursday, February 22, 2018 2:03 PM

Are you sure you're shorting out "all three breakers?"  Could it be that the quarter test is actually shorting out the system breaker which feeds all 3?

It takes an iron man to play with a toy iron horse. 

  • Member since
    February 2005
  • From: Vancouver Island, BC
  • 23,330 posts
Posted by selector on Thursday, February 22, 2018 2:00 PM

Your terminal block does not separate the three 'districts'...it merely feeds all of them at the same time.  Your experiment with removing wires proves this.  The short is the command unit sensing a short via its routing, which includes the terminal block.  So, it dutifully shuts off power to the rails and squawks.

AND----your breakers appear, if they function well, to tolerate more of a short, or are delayed sufficiently in responding to one, that your command unit beats them to the punch and stops the short itself.

  • Member since
    January 2014
  • From: Moneta, VA USA
  • 1,175 posts
Can’t understand system short
Posted by gdelmoro on Thursday, February 22, 2018 12:11 PM

Hi all,

I give up so I’m hoping one or more of you can help.

I have an NCE Power Pro system with radio.  The control box is connected to a terminal strip and then to three NBE Circuit Breakers which segrate the 2 mainlines (Main) from the Sorting yard and Ferry Yard.

If I disconnect the wires from the terminal block feeding the two yards and check track voltage with my rampmeter I get 14.3 ONLY on the Main the other two districts are dead.  

The two yards are gapped and have no connection to the Main lines. If i do the same with each district I get the same the connected one reads track voltage and the other two are dead.  All sounds good.

When I connect all the breakers and all the districts are live placing a quarter on the Main shorts out all three breakers.

Any ideas?

Gary

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