How do you divide power districts?

[daniel_leavitt2000]

I'm starting to look more into DCC systems. Although I really like the ESU systems, I think the NCE PH-Pro Radio is probably the best option in terms of availability, cost, and additional equipment.

I don't recall much discussion on power distribution, So I was wondering how you divide your districts. Do you go be layout location? Mainline VS branches/yards?

I should probably note that I will need to power up to 25 engines on the mainline simultaneously. Conrail used to do light engine moves when the Beacon Park Yard filled up.

[jdcolombo]

There's no real magic to this.  What I did on my layout was divide power districts in a way that equalizes as much as possible the electrical load and avoids a situation in which the load might exceed the 5A rating of my booster.  Then I also tried to take into account how a short on one district might affect operations - in general, I tried to divide things up so that the layout didn't come to an entire standstill because someone derailed on an improperly-thrown turnout.

I have a central main classification yard, that has six eastbound tracks and six westbound tracks.  This yard will always have a lot of engine activity (engines sitting on the ready tracks to take out the next mainline freight; engines for the inbound train; switchers working the yard), so I put the EB yard on one district, and the WB yard on another.  This equalized the electrical load between the two, and if one yard has a short, it doesn't affect the other one.   Similarly, the engine terminal is on a separate power district.  Then I put each major switching area (town) on its own district.  There will be a lot of switching activity at each town during a typical operating session, so this is really about minimizing the disruption of a short.  If someone switching Lorain shorts the track, the folks working the Steel Mill/Rocky River, Fostoria, etc. can keep on with their work.  Finally, each staging yard (each of my staging yards is six tracks; one track is open, the others have trains) is a separate district.  This is once again about power distribution, since five trains each with three-diesels (or one sound-equipped Berkshire) can add up to a hefty electrical load. 

So there you have it.  I have eight power districts: EB Yard, WB Yard, Engine terminal, Lorain, Rocky River, Fostoria, EB staging and WB staging.  These 8 districts are fed by three 5A boosters (one for the EB yard, Lorain, Rocky River and the EB staging; one for the WB yard, engine terminal and Maple Grove; one for Fostoria and WB staging).

My layout is an E-shape in a 30' long by 14' wide room.  You can get a sense of it via this video:

John C.

[mmyers]

I had 4 districts on my now defunct home layout. 2 mains, 1 branch, one yard. I figured the shorts (running switches) were most likely to occur in the yard and on the branch line.

Martin Myers

[daniel_leavitt2000]

Originally, I was planning districts by yard location: Worcester, Westboro/Framingham, Beacon Park/South Station.

New plan: Mainline track 1 (Westbound), Mainline track 2 (Eastbound), Worcester/P&W yard and branch, Worcester/Conrail yard, Westboro yard, Framingham/Nevins, Framingham/North, Beacon Park, South station.

Maybe I should also group all the branches to a miscellaneous division as well.

[tehachapifan]

Welcome to the slippery slope of DCC (which I [happily] started to slide down recently ). Right now only my branchline is DCC but it's probably only a matter of time until my two mains get converted too. An even slipperier slope? Sound decoders!

[GaryHinshaw]

I think you need to distinguish between power districts and circuit breaker districts, or subdistricts.  Obviously you need enough power to supply your entire layout, which will determine how many boosters you need.  For example, a Digitrax DCS100 command station can supply 5 amps, and each additional DB150 booster can supply 5 additional amps.  Your overall load will determine how many boosters you need, and you can figure between 0.1 and 0.2 amps for each running loco on the layout (more if you have sound).  Separately you need to decide how to isolate your track segments so that a short in one subdistrict does not bring down the other subdistricts.  You'll need one circuit breaker card (such as an OG-CB) for each subdistrict. 

On my pike, I split things up so that north staging and half the mainline are served by the command station and 3 breakers, and south staging and the other half of the mainline are served by the booster and 3 breakers.  The setup looks like this:



The breakers are downstream from the power supply so that they trip before the command station does. 

I'm not sure it makes sense to separate your EB and WB mains into different districts because you'll need a separate bus for each track in that case, and it doesn't really gain you much operationally, as far as I can tell.  You definitely want the power districts to be equally divided by load, approximately.  The subdistricts can be divided by operational complexity, as in the examples above.

One other factor to consider: if you are planning on current-sensing block detection, you need to make sure that each detected block is in one breaker district.

[sp org div]

John sums it up well (and nice vid there), but we have found...
Operators are notorious for running turnouts, as common place for not paying attention, so:
I suppose it would be difficult for any of us to over-do the short circuit protection, but each main yard throat deserves a separate breaker sub district (busy yard), each staging entrance likewise, and each industrial area deserves its own also unless not switched simultaneously. 
CTC dispatched RR can take focus off the mains regarding redundant blocking / breaker sub districts, if implemented correctly (the system wont allow the errors humans would otherwise... unless a crew blows by an absolute stop indication  ).  Here all 30+ detected mains / sidings are on 4 sub breaker districts (benign).
We only run 2, 5 amp DCS, broken into 3 power / 12 breaker sub - districts: 4 for main yard / staging throats, 4 for industrial areas / main yard sections between ladders (to handle current load), and 4 for mainline.  There is plenty of power for a stable of over 30 locos / sound / detected rolling stock etc.  There can be hiccups during sessions, but what fun is it without everyone getting an opportunity to get bagged on.   

Jeff
http://espeeoregondivision.blogspot.com/