Power Districts

[JMan]

I’m not sure if this should go here or in the DCC forum!

Is it possible to section a larger layout up into power districts and run it from Railmaster and two elinks, one for the track and one for the accessories? The length of track, I have in mind, is around 80m with 14 to 16 points. I would use something like a DCC Concepts Bbar to distribute the track power to something like a NCE EB1

Cheers JMan

[96RAF]

Usually power districts are associated with dividing the track bus into separate electrically isolated districts. These additional districts are powered by their own power amd signal boosters (i.e. DCC signal repeaters) but controlled by a SINGLE controller in district 1. The booster modules carry the prime DCC signal across into the other districts. 

 

What you are describing in your question are separate track and accessory bus which can be controlled by separate controllers. In Railmaster this is seen as Controller A for locos connected to the track bus and Controller B for points and signals connected to the accessory bus.

 

There are many ways of building a bus and those terminal blocks are a sturdy if expensive way of doing it. You can simply solder the dropper wires to the bus wires, or use simple choc-block connectors or crimp on suitcase connectors (also known as insulation displacement connectors).

 

 There is a way of using a single controller to power both a track and accessory bus using those circuit breakers for isolation. This means if a loco derails due to wrongly set point and creates a short the track breaker will trip but the accessory breaker will remain powered allowing you to correct the point setting and rerail the loco before resetting the track breaker. The breaker linked to is also more expensive than the much simpler twin bus - twin controller set up.

 

Two eLinks set up in RM will do the job, but you will likely need the 4-amp power supply unit to run more than a few locos. If you then see track power problems you can then consider splitting the track bus into proper power discrircits using booster modules.

[Chrissaf]

These drawings supplement Rob's reply above.

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This is the way that Hornby would envisage using the dual controller option. The only difference being that Controller A would normally be an Elite and not a second eLink. Additional 'Circuit Breakers' are not needed as the two eLinks will have their own individual ' short circuit' protection.

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These next two drawings demonstrate Rob's alternative single eLink controller option.

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This first one has a technical issue (an issue that has come up on the forum before). The 'Circuit Breaker' between the eLink and the track, must have a trigger current that is significantly less than the 'short circuit' trigger current of the eLink. Recommendation is less by half. Assuming the eLink is upgraded to the 4 amp PSU, then the 'Circuit Breaker' needs to trigger at 2 amps [2.5 amps at most]. If this recommendation is ignored, then the eLink can still go into 'short circuit' protection either as well as or instead of the 'Circuit Breaker'. The eLink 'short circuit' protection trigger current is set at 3 amps and is not adjustable.

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This one has the advantage that the factory supplied 1 amp PSU can still be used with the eLink as the 1 amp supply is only being used to provide the DCC Signal to the Boosters. Assuming the 'Boosters' are powered by 4 amp PSUs. The 'Circuit Breakers' still need to trigger less than this 4 amps as it is assumed that the 'Boosters' will also have 'short circuit' built in protection.

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Personally IMO, I feel that including 'Circuit Breakers' is 'overkill' in the UK. They seem to be primarily a USA used device. Most (UK?) 'Boosters' usually have 'short circuit' protection built in to them.

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[Yelrow]

Thats the way to do it,.

[96RAF]

Impressive basic information Chris

We really do need an area on the forum where this type of generic knowledge can be lodged for future reference. 

[Fishmanoz]

JMan, now you have a comprehensive answer to your question, with alternatives. However, your next question may well be, do I really need to?  The answer to this is probably not, but let me go further. 

80m of track - sounds like quite a lot, certainly not a 6 x 4 twin oval job.  But in DCC, you don't power the track as such, you power the locos on it.  So if you are only ever going to run 3 locos at a time, even sound locos, then an eLink with its original 1 Amp supply will most likely run it without overloading. But if you intend to have 20 locos running on it, then, apart from needing to be a 2-headed octopus yourself to keep control of all of them, you'll need to split it into 2 power districts, one run by an eLink with the 4 Amp supply, and the other by a power booster connected to the eLink track output. 

16 points - not many, chances are you can run them from the eLink already running track, except maybe for inrush current setting them all on startup, depends on the type of motors you use. 

Then, a third and final question - it all works fine from the single eLink now but I'm thinking more locos and more points later - what can I do to future proof myself against this?  The answer is simple - wire it up with separate buses for 2 power districts and for the points, but then connect all 3 buses to one controller for now.  Then you can easily split later if you get overloads. 

How do you make 2 power districts (oops, 4th question)?  Dead simple, just install insulated rail joiners such that the two districts are electrically separated from each other, then give them separate power buses running back to the controller initially, then one district via a booster when eventually needed. 

[JMan]

Hi, thanks all for your great replies and info, thanks Chrissaf for the circuit diagrams. I do have a 4amp power supply as I was having start up problems, on my old layout, with the original 1amp power supply. I haven’t decided on any equipment yet, hence the “something like”, I will have to chat further with my local suppliers. However, like most, they are extremely low on stock, I guess a lot of hobbyists are stocking up on-line during the lockdowns.

Again, thanks and stay safe,

JMan  

[Yelrow]

Fishy, power booster, wash your mouth out. Does it meet your double garage rule.

[Fishmanoz]

You are of course quite correct John (double garage rule - you don't need a booster until the layout fills both car spots), but given all the talk and diagrams here, I suggested the middle course - fitted for but not with. Costs only a handful of IRJs and a bit more wire, but if both cars end up out in the weather, you are laughing. 

[JMan]

"you don't need a booster until the layout fills both car spots"

My planned layout is aprox 5.7m x 4.8m (18.7’ x 15.7’), mainly around the walls with a peninsula. As I run Australian models and some have a minimum turning radius of 0.61m (24”) most of my radii are over 0.7m for more prototypical running. Also, I have tried to keep my inclines/declines to as close to 2% as possible. Both these use up a lot of acreage.

[Fishmanoz]

Filling 2 car spots is of course a proxy for large and complicated enough that it is possible to be running more than 10 locos at once, hence overloading a single 4 Amp controller.  The significant thing here is that, even under RM program control, running 10 at once will require many of them to be doing their own thing in separate areas of the layout without active intervention, while you actively control say 3 of them elsewhere.

 

You could of course have 20 or more locos sitting stationary on the track using virtually no current (except maybe for sounds).  It is only the running locos that count, remembering you are powering the locos not the track, as per my reply further up page 1.

[Friendly Fryer]

I am running 80m plus  of track on my tailchaser in the loft (Notes from the loft on rmweb). I have one Elite supplying one bus for everything and it's all good. However I am using  DCC Concepts DIP/SS motors  (I have about 36)  whicc don't draw much power. Also I might only ever run 4 locos together at one time though these do have sound and I have coach lighting too. 

 

So from my experience of doing this is it all just works.  I just have to be very methodical  when I make chnages as chasing down faults on a large layout is pain and has cuaght me out once or twice.  However the wring is really simple even with two separate return loops.  The only difficulty I had was setting up the more exotic three way points and double slips as I have electrofrogs.  I had always thought about seom more exotic solution like the excellent advice here but to be honest I can alsoways make that happen if this does become an issue.  So I'd encourage you to start simple but do use lots of droppers from bus tor track to make power disrtubtion reliable and I supply every section of every track from the bus so the joiners are not a point of failure..  

To avoid shroting the layout by having points set incorrectly I have "safety rails" approaching any point and these sections only get power if the poitbn is set the right way. This is not great as the train will just die (no sound for example) but stops shorts when there is a lot going on or friends are usng my layout however reliability is king for me.

Good luck and share how you are getting on

 

[JMan]

Hi Chrissaf, are you suggesting an Elite because it has a 4 amp PSU rather than an eLink because it only has a 1 amp PSU? I will be using Railmaster to control the layout and 4 amp PSU's are available for eLinks.

[Chrissaf]

You have mis-interpreted what I said.

 

I just said that when Hornby RailMaster Support [hrMS] included the Controller A & Controller B option that they envisaged that the take up would be by users who had started out with an Elite and then bought the RailMaster / eLink bundle as an upgrade to 'Software Based' control. These users could then make use of both the Elite and the eLink and save any wasted investment. Also, the eLink box on its own without the railMaster software is not an official shop purchase from Hornby. Thus again, marketing envisage the Elite AND eLink scenario I have just outlined. Second eLinks are typically sourced as second-hand purchases.

 

The RailMaster dual controller setup will work just as well with two eLinks as controller A & B and as you quite rightly identify, the Hornby P9300 4 amp power supply is the official Hornby power supply upgrade for both the Hornby eLink and also the Hornby Select.

[JMan]

Thanks for the update.