Quarter Test - Does not work on remote sections

[StewRRFan]

I have a Digitrax DCS51.   There are three sections of the layout that will not pass the quarter test. 

The setup is as follows.

14G to Mail Power Block.
14G to TamValley autoreverser from Power Block.  Out from AR to powerblock.  20G Feeds from PB to track.

1 of the 4 sections will pass the quarter test.  On the other 3, the quarter will "sing" but not trip the DCS51 breaker.  The 3 section not passing involve the AR's. 

Trains run with no problems from each section to section. 

Any thoughts on why the DCS51 is not tripping?  Thanks.

[peteski]

Any thoughts on why the DCS51 is not tripping?  Thanks.

Well, probably because the short-circuit current is not high enough to trip the breaker.  Why? Because the combined resistance of the wires, track, and the quarter is high enough to lower the current enough no to trip the breaker.

How long is the run of the 14 AWG wire between the breaker and the track feeder closes to thwere you put the quarter?  What gauge wires are used as track feeders?  How long is track between the closest feeder and the spot you place the quarter on?

The other possibility is that this particular breaker is defective.

Can you create a short circuit for that breaker physically closer to it and see if it trips?  Detach the wires going to the track from that breaker and take a shoer piece of 14 AWG wire across the terminals right at the breaker.  That should definitely cause it to trip.

[StewRRFan]

Petski - Thank you.

How long is the run of the 14 AWG wire between the breaker and the track feeder closes to thwere you put the quarter?  <5'

What gauge wires are used as track feeders?  20/22G

How long is track between the closest feeder and the spot you place the quarter on? <3' in most cases

Can you create a short circuit for that breaker physically closer to it and see if it trips?  I can create the short at the main DCC power bar.  The sub sections - no.

Detach the wires going to the track from that breaker and take a shoer piece of 14 AWG wire across the terminals right at the breaker.  That should definitely cause it to trip.  - It does on the main, but not the others.

[GaryHinshaw]

Do I understand that you have 1 section on unswitched power and 3 sections on AR's?  Could you draw a wiring diagram showing how the AR's are hooked up, and where the quarter test fails in relation to them?  I wonder if multiple AR's are fighting each other (causing the singing).

[John]

Just what I've read so far, I would start looking at the ARs .. make sure they are set correctly .  the drawing would be nice ..

[StewRRFan]

Here is the drawing along with how I have this wired and its order. The yard works with no issues.  (Built 1st).  Quarter will short out here and it is wired off the main PB.

[StewRRFan]

A few real pictures if that helps.

[GaryHinshaw]

Are there tracks connecting the two "yard tracks" in your sketch?  If not, I think you only need an AR under C.  In general, it is not a good idea to have boundaries where two AR's meet, because they can both try to switch polarity when a short is detected, then they try to duke it out for supremacy. 

[StewRRFan]

Yes, Gary.  Tracks are connected in the yard.  Let me try disconnecting the AR's other than C.  Thanks

[StewRRFan]

No dice.  The yard does not "loop" around so without isolating the other sections, I short out.

[John]

I need to see some better pictures .. something that encompases the whole layout if possible .. especially around this yard area . .in the meantime .. disconnect all the ARs except A .. and put a gap where I drew it in the picture ..  you dont need B or C if your diagram is correct ..

[lyled1117]

I understand that the Tam Valley AR can be used as a circuit breaker, but it also can function as a polarity reverser as well while functioning as a breaker. Is it possible the trip current for the reversing feature is too low that it triggers before the breaker of the Zephyr? Was your intention to turn off the reversing feature, but perhaps didn't? The 'singing' of the quarter could be the reverse function toggling at a lower setting than the breaker current.

Lyle

[peteski]

I need to see some better pictures .. something that encompases the whole layout if possible .. especially around this yard area . .in the meantime .. disconnect all the ARs except A .. and put a gap where I drew it in the picture ..  you dont need B or C if your diagram is correct ..

John, we went through this setup in the past (last year).  See https://www.therailwire.net/forum/index.php?topic=34688  for all the interesting details.

[StewRRFan]

Petski - Yes I did post on this last year but got the layout running with the help of a few local people.  The layout operates fine.  My concern is with it not shorting out.  I do not want to a "melt down" at some point.  I will try the suggestion above and post an additional map of the yard tomorrow.  Today is a travel day.

One question in the meantime - Could running the power feed from the main bus into the AR first and then the output to the track feed bus be causing the issue?

Thanks everyone.

[GaryHinshaw]

The wiring you describe sounds like how it is supposed to be set up.  Now a question: could you clarify what you mean by "DCC Bus - Power Block" in your diagram?  Is there an AR in there?  If so, that might cause the problem you have.  In general, the AR's should be fed directly off the DCC bus, not off another breaker of any kind.

Now that you have clarified the yard situation, I might recommend placing the yard are under one AR and removing the rest.  (You're always better off using as few AR's as necessary - and you really should avoid having two adjacent AR-controlled blocks for the reason I noted in a previous post.)   Here is a possible scheme:



The yard would be under the AR, the main loop and the legs approaching the wye would all be on the main bus, and you would only need one AR and the three gaps, shown in red.  The only caveat is that you have to be careful about two different trains crossing two different gaps at the same time.  Would that be a common occurrence, e.g. a train entering the left side of the yard while another leaves on the right at the same time?