Power supply

[SD90]

My layout is progressing, I'm still in the benchwork stage, but have the middle level benchwork almost finished. I have a question about power supply.
The layout is basically a point to point around the wall triple deck, with a helix going from level 1 to 2 and 2 to 3. (There will be an option on each level for continuos running.) The basement is 31'x30' with a 7'x8' bump out where the helix will be. There will be 500' of mainline run, will 1 Railpro power supply be enough, or should I get 2?
If I place the power supply in a corner, and have 3 bus lines going out (1 for each level) in each direction they will be about 60' long each, plus the helix. I'm planning on using 14 gauge bus wire.
If I did use 2 oder supplies, would I need to insulate the rail joints where they meet?

[nodcc4me]

You can get away with one power supply if you limit the bus wires to 30 feet with feeders placed about every 6-10 feet. If you decide to use two power supplies, one at each end, you will need to place an insulated joiner in the red positive rail.

That's going to be quite a layout. Waiting for pictures. 

[SD90]

With the basement being 30' on each wall, the runs will have to be 60' each, so I'll need 2 I guess?
I'd just have to insulate one wire, not both?

[nodcc4me]

Yes, just the red wires must be insulated from each other. Can you place the power supply in the corner?

[Alan]

[Alan]

look at the voltage drop in the calculator above and below. Use 12 gauge wire.

[Alan]

Here's a thought for you... Using these you could afford to have many of them spaced around the layout. That would allow small gauge bus wires and almost no measurable voltage drop.

http://www.ebay.com/itm/5A-15V-AC-Adapter-Power-Supply-Charger-Fr-Toshiba-Satellite-Portege-Tecra-Laptop-/321835366443?var=&hash=item4aeee1f82b:m:mQx8MHuKXAaraAOtsbOdPmQ

[Alan]

One more thought and then I will stop. I promise. 

Anytime multiple switch mode power supplies are used in a parallel configuration (which yours will be when a wheel bridges the rail gap) you should put a high current schottky diode in the positive supply lead to isolate the voltage regulation sections of the power supplies from each other else strange things can happen.



http://www.mouser.com/ProductDetail/Fairchild-Semiconductor/SB1245/?qs=sGAEpiMZZMtQ8nqTKtFS%2fDJWInRO8leYd%2f7HCUlqa%252bw%3d

 

[SD90]

Yes, just the red wires must be insulated from each other. Can you place the power supply in the corner?

Yes, the power supply could be placed in the corner, any of them.
Imagine the basement is a square, with the 7x8 bump out at the top, I thought of putting the power supply at the top, so I could power the helix and have 3 bus lines (1 for each level) going in each direction from there.

I appreciate the replies!
Thank you!

[SD90]

If I use more than 1 power supply, can I just insulate both rails?

[Alan]

If I use more than 1 power supply, can I just insulate both rails?

No, unless the PS manufacturer specifically states the units can be paralleled. Typically, you won't find that in low cost consumer products. It all depends on what circuitry the manufacturer uses for voltage regulation. We have no way of knowing this.

As a loco crosses the gap both power supplies are connected via the front wheels and back wheels. The momentary condition may or may not be a problem. But what if the loco sits parked straddling the gap? The regulators may become unstable creating a runaway voltage effect. Poof goes your modules.

Another consideration is short circuits. If a derailment caused short occurs while the gaps are bridged then the full current from both PSs will flow through the short. A pair of 5A PSs = 10A which melts trains.

Here is a two page document explaining how to parallel connect PS. Can you do everything on page 1? If not then see page 2.
http://www.frei.de/assets/templates/frei/Dateien/Dateien/PDF/Stromversorgungen/en/Technische_Beschreibung_Parallelschaltung_ENGL.pdf

The diode solution is easy enough and costs less than $5. Then you don't ever have to worry.

[yvesmary]

Alan,

As a loco crosses the gap both power supplies are connected via the front wheels and back wheels. The momentary condition may or may not be a problem. But what if the loco sits parked straddling the gap? The regulators may become unstable creating a runaway voltage effect. Poof goes your modules.

Does this apply to my setup? I have a PWR-56 powering the lower level which goes up a helix and at the top the rails are gapped (insulated joiners) and the upper level is powered by another PWR-56.

Thank you,
Yves in Alberta

[William Brillinger]

Any layout with more than one PWR-56 should follow the instructions in the PWR-56 manual on Page 10.

www.ringengineering.com/RailPro/Documents/PWR-56UsersManual.pdf

[G8B4Life]

Does this apply to my setup? I have a PWR-56 powering the lower level which goes up a helix and at the top the rails are gapped (insulated joiners) and the upper level is powered by another PWR-56.

No. As Bill posted, the PWR-56 manual provides all the info needed for using multiple PWR-56's together. You just have to gap the positive rails and install at the appropriate place. Unless I'm grossly mistaken Ring would have built in all the required circuitry to handle race conditions, overload from shorts at power boundaries etc. I've never opened a PWR-56 up to see what's in there but I highly doubt it'd just be a radio controlled on/off switch.

All the info from Alan (which is great info, thanks Alan) would apply if you were using other power supplies, like the one's that Alan uses and I have that may or may not be specifically made to work together.

- Tim

[Dean]

May I presume that all this great information is for layouts that are RailPro only.
DCC has a whole different set of rules.