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DCC bus planning - advice wanted


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Hello

 

As described in my layout thread I'm in the process of building this layout, about to start tracklaying.

 

p642593311-4.jpg

 

I have an NCE power cab and have already bought the CP6 overload protection (light bulb) thing. The points will be dcc controlled using the NCE macro functions. The point motors will be Cobalts and the accessory decoders combination of NCE switch-8s and switch-its.

 

I'm trying to decide how to set up the dcc bus, to what extent to divide things up for reliability and fault finding; the CP6 allows up to 6 buses, do I need that many - I don't the wiring to be too complex. The branch line will be a separate bus, due to exising dodgy tracklaying more chance of faults there and there will be a separate accessory bus. Should I have different zone for the staging tracks and /or each direction.

 

Hopefully my question isn't silly, any advice would be welcome.

 

Thanks

 

Jon

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Not silly at all. I think what you are describing are often known as Power Districts. If you get the separation right, you can rely on the rest of the layout to continue running when an operator error causes a short circuit or derailment. I would suggest that each main line have it's own bus, ditto each set of storage sidings. The branch really needs two districts - one for the sidings at the main station and branch itself, another for the branch terminus. That's your six. I'm not sure about a cutout on the accessory bus, having not found the need for one myself, but then my accessory bus doesn't do much!

 

I am not familiar with the CP6 item, but can say that if you use sound decoders in any number, then not every cutout on the market is equal to the task of restoring power after a short.

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Hi

What has already been stated is good advice, but do remember the NCE CP6 units are not power cut-outs. They do not remove any track power.

They are festoon light bulbs and act as 'current limiters' to the area of a short and illuminate to indicate the short in that section (district or zone) has occurred. The power is still flowing in the section.

If you want total isolation then you'll need all electronic overload cut-out devices. Note too that many wont work well with the basic PowerCab as its output current is too low. Most need a DCC system capable of delivering around 3.0Amp or more.

Also when you are installing any type of zonal / district protection whether its CP6 style of lamps or cut-outs you'll need to install insulated rail joiners to all tracks leading into and out of that zones area or arrange to have gaps in all rails in place of the IRJs.

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Live crossing points in the continuous run circuits? If so you need a complete insulating gap in both rails somewhere in each unique circuit. And 'the rails' includes the power busses connected to them. Be careful with your power district arrangements not to inadvertently bridge the rail gaps.

 

As drawn you can put the rail gap in very conveniently on the lift out section, just connect the busses from only one side to power the rails on the lift out piece, and ensure the rail ends of the lift out section do not contact those of the fixed boards, and the job is done without any further bother.

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In contrast to some previous advice, I'd rather not relegate sections according to that scheme. My suggestion:

1) the main station, both directions and terminus of the branch line, as well as the approaches, (the blue track in your track plan)

2) the branch, as a whole,

3) fiddle yard, as a whole (green track)

 

This way, you won't have the trouble of crossing multiple power districts with the associated problems and you can cut down on the number of insulated joiners you need (10: 2 for the branch and 4 each for insulating the main lines between station and fiddle yard)

 

Thanks - interesting to get a different opinion. I was wondering whether given that layout is not that large largely for solo operation, keeping trains running if a fault occurs is not so much the issue, but narrowing down where the fault has occurred is?

 

.... And I concur you really need a proper set of circuit breakers, car lamps just aren't cutting the mustard :rolleyes:

 

Not naysaying this but in my ignorance I just have gone with what NCE recommended to use with the Powercab.

 

Once again thanks

 

Jon

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