Location of Power Districts

[LKOrailroad]

I post regularly in the Layout Engineering Reports section but this is my first post in the DCC section. Hoping you can give some advice.

I am in the process of determining the breaker protected district locations on my layout in preparation for DCC power bus wiring. Currently I have the layout divided into these individual blocks:

• Main line in ≈20ft sections (within reasonable viewing distance from center point)
• Double ended yard split in the middle of classification tracks into 2 blocks - east end, west end
• High density industry switching area (labeled Firestone Complex on track plan)
• Engine service area
• Mine branch
• Major town's switching (labeled Lapeer on track plan)

Does this sound right to you? Are there other concerns I should give thought to? Track plan is here if needed: http://www.lkorailroad.com/track-plan/ Working on upper deck only at this time.

Thanks in advance,

[John]

My entire layout is separated into 4  blocks .. its a double decker as well ..  but I isolate my yards / towns from the main with a toggle switch so i can troubleshoot .. I would put each major yard / town on your layout on separate breakers, but other than that . .a breaker for the upper, and lower levels ..

[trainforfun]

+1 John .
A couple of well placed toggle switches is a good avice !

Nice construction and very nice layout , it will be fun to operate . 

[peteski]

Instead of one breaker for all the main line, if you are planning on running multiple trains at the same time, I would split the main line into couple of sections. That way a short under one train does not affect other mainline trains.

I'm also not sure why you need multiple breakers for the yard. Will there be couple of yard operators running the yard? Do you expect them to regularly run the switches (or otherwise cause shorts)?

Make sure that the trip current of the breakers is less than the current that trips the booster's internal breaker.  But I like the idea of electrically splitting the layout into multiple sections. Even if several sections are on the same breaker. As long as each section is connected through a DPST switch (which will totally isolate both rails) to the same breaker. That arrangement makes troubleshooting much easier.

BTW, bus (as in electric conductor) is spelled with one "s". "Buss" means to kiss ( http://www.thefreedictionary.com/buss ) 

[LKOrailroad]

toggle switch so i can troubleshoot

Toggle switches and breakers??? Can you elaborate on why the redundancy? Or, am I misunderstanding?

Instead of one breaker for all the main line, if you are planning on running multiple trains at the same time, I would split the main line into couple of sections. That way a short under one train does not affect other mainline trains.

On the current plan the main is separated into 5 districts each about 20' in length. Too many, too few?

Will there be couple of yard operators running the yard?

Yes, one working the east end another working the west end.

"Buss" means to kiss

I have been known to get quite intimate with the layout when alone      Spelling noted, thanks.

[C855B]

BTW, bus (as in electric conductor) is spelled with one "s". "Buss" means to kiss ( http://www.thefreedictionary.com/buss ) 

Yes... but Buss is also a long-established brand of fuses, so we have come full circle here.

[peteski]

Yes... but Buss is also a long-established brand of fuses, so we have come full circle here.

I'm aware of Buss fuses. But in this instance buss was used as a description of 2 conductors making up a power bus. 

[peteski]

LKOrailroad,  I guess we should clarify things. DCC power boosters supply DCC power to the track. Most (if not all) have a built-in short circuit protection.  However, on most larger layouts, additional DCC circuit breakers are used to distribute the power to the track. The output of the boosters is passed through the DCC circuit breakers. Breakers can be electronic or even a simple automotive light bulb.  The tripping current of the breakers is less than the tripping current of the booster. That way, if there is a short in one of the track sections, only that section will shut down. The booster will still supply current to the remaining sections. Breakers are much cheaper than power boosters.

I suppose you could get as many boosters as there are sections of track, but that would be a major overkill for N scale.  You don't need all that current.

I think that you are creating too many separate sections. Again, N scale trains do not need all that current and operators usually aren't careless enough to constantly cause shorts.  What you need to to is figure out the power requirement of your layout. That will indicate what kind of boosters to buy. Then you can decide how many breaker-protected sections you will create.   But the idea if having many isolated sections (powered through a toggle switch) is good. That way, even if multiple sections are powered from the same breaker or booster, if there is a short, you can quickly narrow down location of the short by simply turning off each section until the short goes away.   This arrangement is not necessary, but helpful.

Couple of issues ago, Model Railroader had a nice writeup about how to calculate the DCC power needed for a layout.  Not sure if you have that magazine but if you do, you might find that article helpful.

I would love to see a picture if you bussing your layout! 

[LKOrailroad]

Peteski,

Perhaps a little clarification on my part is in order too. I'm good on the technical aspect of wiring/powering my layout. My question arose more from an operators experience standpoint. Drawing from your experience operating on different layouts have you found some had too few districts while another may have had so many as to become over-engineered? Have you been working a local when another train caused a short and thought to yourself "why didn't he put this section on its own district?". Those sort of experience questions.

BTW the layout is HO not that it matters.

Sorry, there will be no published images of me bussing my layout. We keep that part of our relationship private.   

[John]

Ok .. let me also be more clear.  I have three Digitrax boosters, and one PM64 (4 circuit breaker) ..

The layout is fairly large, both upper and lower level.

Each level is divided into two power districts, One booster runs the lower level, another booster runs the upper level, and the third booster is my command station.

I also have two major yards, and a large city / industrial area. Each of the yards is isolated from the main power bus in the district, so that if there is an issue with one of the turnouts, or the operators run the frogs, I can quickly disconnect that yard from the layout using a toggle switch. 

The major town area is also on a separate bus.  It's overkill, but I've had wiring issues in the past, and having smaller sections that you can use to isolate the layout into is good basic troubleshooting.

When I learned electronics a long time ago, I was taught to always break the circuit into 1/2 ..

Hope this clears up my earlier post - I was using a small tablet to answer and cut some corners.

[peteski]

Peteski,

Perhaps a little clarification on my part is in order too. I'm good on the technical aspect of wiring/powering my layout. My question arose more from an operators experience standpoint. Drawing from your experience operating on different layouts have you found some had too few districts while another may have had so many as to become over-engineered? Have you been working a local when another train caused a short and thought to yourself "why didn't he put this section on its own district?". Those sort of experience questions.

BTW the layout is HO not that it matters.

Sorry, there will be no published images of me bussing my layout. We keep that part of our relationship private. 

LKOrailroad,
Now I understand your question. In my experience of operating DCC-equipped layouts (any scale) I don't  think that I have yet encountered a layout with too many separate power districts.  But even on the layouts which IMO didn't have enough districts, I didn't find that the (very infrequent) glitches which would shut down half the layout were not all that annoying to me or the other operators. The operating sessions are staffed with seasoned operators who in most cases pay attention to where their train is heading. If the trackwork is very good, short-causing derailments are rare.  In my experience, most short circuits are caused by someone running through a switch which is set against them.  Like I said, this does not happen often, and if it does, the problem gets solved in just few seconds.

IMO, I would call your planned number of separate power districts  a bit over-engineered.  I don't think you really that many for reliable and enjoyable operation.

EDIT: fixed couple of spelling and syntax mistakes. 

[LKOrailroad]

Ah, that's the sort of experience answer I was hoping for . Thank you.

I have decided to not break the yard into two halves. As for the main, it looks like I will need 5 sub-districts. That way if a problem occurs on any given sub-district an operator will be able to see the whole sub-district i.e. not behind backdrop, not around the corner, etc. Thanks for the input.