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Short Circuits

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  • Member since
    September 2004
  • From: Dearborn Station
  • 24,281 posts
Posted by richhotrain on Sunday, September 9, 2012 9:15 AM

Viewing the OP's track diagram is complicated by the fact that it is presented as white on black background, the number of elevated crossings over grade level tracks, and the sheer number of parallel tracks and crossovers.

So, I have prepared an alternative track diagram.  Imagine that trains move clockwise, headed east across the top of the diagram, south down the right side of the diagram, west across the bottom of the diagram and north up the left side of the diagram.  As the tracks disappear off the right side of my diagram they actually form a continuous loop as seen in the OP's diagram.  Likewise, as the tracks disappear off the bottom left side of my diagram they also form another continuous loop as as seen in the OP's diagram.

Since the layout is essentially a continuous loop (a folded dogbone, if you will) with yards and sidings, the tracks headed east are colored in red, and the tracks headed west are colored in black.   Although the lines each represent single tracks, think about red as the outer rail and black as the inner rail.  If red connects to black, you have a reverse polarity situation.  That occurs twice in the diagram, represented by track colored blue.  It occurs where the left leg of the wye connects to the track above the wye, and it occurs at the crossover to the left of the wye. 

Therefore, the affected track needs to be isolated to create a reversing section.  To fully isolate the reversing section on this layout, four sets of gaps must be created, as indicated by the purple lines.  The issue here is the length of the reversing section.  Of course, if you place the gaps where I indicated, the reversing section is pretty small.  The reversing section can be lengthened by moving the gaps further away from the wye as long as the reversing section is fully isolated from the main layout.

As Randy, myself, and others have pointed out, the wiring is crucial to proper performance of the AR-1.  The input side of the AR-1 (terminals 4 and 5) must be connected to the main bus wires.  Any feeder wires inside the reversing section must be connected to the output side of the AR-1 (terminals 1 and 2).  No feeder wires from the reversing section should be connected to the main bus wires.

Rich

 

Alton Junction

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  • From: US
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Posted by alloboard on Monday, September 10, 2012 12:51 AM

     Thanks for your effort and time you took to draw and simplify the map, very creative. I have completely isolated the loop as indicated in the earlier threads. I am now waiting to wire a Digitrax PM42 that I ordered.

  • Member since
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  • From: Dearborn Station
  • 24,281 posts
Posted by richhotrain on Monday, September 10, 2012 4:36 AM

alloboard

     Thanks for your effort and time you took to draw and simplify the map, very creative. I have completly isolated the loop as indicated in the earlier threads. I am now waiting to wire a DigitraX PM42 that I ordered.

While you are waiting for the  DigitraX PM42 that you ordered, you could test the setup with a simple DPDT switch.

Rich.

Alton Junction

  • Member since
    February 2003
  • From: US
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Posted by alloboard on Tuesday, November 13, 2012 9:49 PM

     Is there a jolt or not on a passing train when  DPDT, Digitrax AR1, or PM42 is working at the reverse loop, when a locomotive crosses the insulated gap from the short circuit district to the reversing district?

  • Member since
    September 2004
  • From: Dearborn Station
  • 24,281 posts
Posted by richhotrain on Wednesday, November 14, 2012 4:20 AM

alloboard

     Is there a jolt or not on a passing train when  DPDT, Digitrax AR1, or PM42 is working at the reverse loop, when a locomotive crosses the insulated gap from the short circuit district to the reversing district?

alloboard, I am not clear what you mean by "jolt".  Can you explain what you mean by that term?

Is it an electrical occurrence such as sparking, or a physical movement of the loco such as surging or jerking?

Also, what do you mean by the term "short circuit district" as opposed to the term "reversing district"?

I always refer to the areas of the layout as "main section" and "reversing section".

Rich

Alton Junction

  • Member since
    February 2002
  • From: Reading, PA
  • 30,002 posts
Posted by rrinker on Wednesday, November 14, 2012 7:31 AM

 Assuming the AR1 or PM42 is set correctly, or you flip the DPDT BEFORE the loco hits the gaps, no, there should not be any real noticeable jolt. If you creep over the gap with an autoreverser in use, there might be a slight hesitation. With a DPDT switch, there should be absolutely none, ever, because you are just crossing over gaps with the correct polarity on either side. Another plus for the idea of changing the polarity via a relay controlled by the switch motor (a couple of circuits for this have been posted ont he Digitrax Yahoo group - does need a switch motor like a Tortoise though). Rather than first have a problem (a short) which is detected and corrected by the autoreverser, the idea is to never have the short in the first place.

               --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
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  • From: Dearborn Station
  • 24,281 posts
Posted by richhotrain on Wednesday, November 14, 2012 7:42 AM

Still wondering what a jolt is, and what the OP means by short circuit district.

Rich

Alton Junction

  • Member since
    February 2003
  • From: US
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Posted by alloboard on Thursday, November 15, 2012 12:49 PM

It is an electrical occurrence such as sparkingand jerking. A short circuit district is a district created by a Digitrax PM42 to manage short circuits or auto reversing.

  • Member since
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  • From: Dearborn Station
  • 24,281 posts
Posted by richhotrain on Friday, November 16, 2012 6:12 AM

alloboard

     Is there a jolt .........when a locomotive crosses the insulated gap from the short circuit district to the reversing district?

alloboard, I am still not clear what the difference is between a "short circuit district" and a "reversing district".   But I assume that you are referring to a locomotive crossing from the main section of the layout into the reversing section.

If the locomotive is sparking and jerking, it sounds like it is shorting but still moving which tells me that the loco is moving so fast that the system recovers in time to prevent a dead short.

What is actually happening on your layout?  Is a short occurring?  What happens if the loco is moving slowly as it crosses the gaps from the main section into the reversing section?

Rich

Alton Junction

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