PWR56 Question

[DaveB]

Question:  Building a new layout. The room is 32x16. Will have 150 ft of main line with 3 passing sidings, a 26 ft 8 track switch yard and several industrial sidings. I have 1 PWR56 that was on our smaller previous layout.  Will 1 PWR56 run this layout or would it be better to have a second one?  Ring instruction manual says 30 ft max on 16 gauge bus lines, I will have longer than that. What would be the recommendation for wiring?

Thanks, Dave

[nodcc4me]

32' is pretty close to Ring's specs. I would say try it with one PWR56 centered on the layout and check the voltage at the ends of the run. If it is low you can get another power supply and adjust the location of the first one.

[G8B4Life]

It should work fine, Rings recommendation of 30ft is for 16ga wire. Go heavier gauge and you can run your bus longer. I know Bill runs longer than 30ft on his layout but I forget the length he said, and what gauge wire he used.

As Al mentioned, divide the bus into two halfway along and put the PWR-56 there, that way if the total bus length was say 100ft then each leg of the bus from the PWR-56 would only be 50ft long. If you had a really really long bus run you could get into ringing territory (http://www.lkorailroad.com/powering-the-lko-part-iii/) but I've no idea how long that is.

Another question to ask alongside is how many trains do you plan to run? the PWR-56 is only a 3A supply and it sounds like you have the potential to run quite a few trains at the same time.

If you were to go the route of checking the voltage at the end of the bus, you really need to have a load connected at the end to give a true indication of what the voltage really is when in use.

- Tim

[Alan]

Your first concern should be capacity. On a layout as large as yours it seems likely there could be many powered units (locomotives, sound units, lighted cars, etc.) in operation at any given time. The first thing I would do is try to put a number on that. Estimate your maximum equipment requirement not your typical equipment requirement. From there you can estimate how much power is needed and thus how many PWR56 to use. This makes sure you don't run out of power at some random time.

Distance is your second concern. The rule is simple - longer wire runs require larger wire size. The PWR56 quotes 16 gauge because that is the maximum wire size its hookup terminals accept. There is nothing wrong with using a short (12") piece of 16 gauge as a pigtail from the PWR56 to hook to a bus that is of heavier gauge for the long wire run. This is how you would go about it if you utilize a single PWR56 on a large layout.

When you run the numbers I doubt a single PWR56 is going to be sufficient. Multiple PWR56 can solve both the capacity and distance issues. By mounting two or more PWR56 evenly distributed around the layout you get more power and it shortens the bus run for any one PWR56. This allows you to use smaller size bus wire.

PWR56 also act as signal repeaters so multiple around the room boosts the HC / LM signals. Potentially a useless feature in a 32x16 room. Have found no need for repeaters in my room of 28x32. In fact, I don't have a Ring power supply at all. Just HC and LMs.

Non-hobby power supply like mine is another option for you. I use a single 15V generic switching power supply (from eBay no less). To this I use a single 12 gauge bus around the layout (pic below). This arrangement has some nice attributes:

• Minimum number of components.
• Easiest installation.
• Less expensive and more powerful than hobby brand power systems.
• Single, easily accessed location for power supply. No crawling under the layout.
• Power supply can be upgraded to higher wattage if need arises with no change in wiring. Just swap out supply.
• 12 gauge bus has no practical limit on number of trains running simultaneously.
• Power is relatively uniform around the whole layout even under varying loads.

The arrangement forces me to give up the power supply to HC reporting feature. But c'mon, how useful is that feature anyway? Here are two blog posts if you want to see my solution:
http://www.lkorailroad.com/powering-the-lko-part-i/
http://www.lkorailroad.com/powering-the-lko-part-ii/



Figure out your max trains and we'll help you from there.

[Alan]

... If you had a really really long bus run you could get into ringing territory (http://www.lkorailroad.com/powering-the-lko-part-iii/) but I've no idea how long that is.
- Tim

Tim makes a valid point about very long wire runs but don't lose sleep over it. I sometimes tend to go off the deep end with the electrical stuff only because it is my "other" hobby. Ringing is unlikely to present any practical problems except in rare odd cases. Besides, all DC power distribution systems, Ring or otherwise, are equally susceptible to ringing so if it happens, it happens. The brand of power supply makes no difference. There are easy fixes to suppress ringing should it occur.

Now if this were a DCC setup then yeah I would be concerned about ringing.

[G8B4Life]

The arrangement forces me to give up the power supply to HC reporting feature. But c'mon, how useful is that feature anyway?...

Maybe not the reporting feature but I find the PWR-56 excellent for the LM tester board I made. I use the CI-1 at the desktop to do all the downloading and initial setup etc so it makes a great power supply for that; I can use the CI-1 to turn the power on or off to the LM without reaching for a switch, or tipping over a loco on the track.

For the far distant future layout though yes I have a Meanwell SMPS for that, simply for the available power. It'll probably be an overkill.

- Tim

[DaveB]

Thanks for the input. I will go with a second PWR56. That will keep my bus lines shorter and will have plenty of power for my engines and whatever else I want to add.  That seems to be the best rout because I don't understand all the electrical ins and outs like Tim and Alan ( I have learned a lot from you guys, thanks ).

Thanks, Dave

[Alan]

Thanks for the input. I will go with a second PWR56. That will keep my bus lines shorter and will have plenty of power for my engines and whatever else I want to add.  That seems to be the best rout because I don't understand all the electrical ins and outs like Tim and Alan ( I have learned a lot from you guys, thanks ).

Thanks, Dave

Two PWR56 will certainly work but do not fear the generic solution. There literally is no difference other than which unit you buy. No electronic knowledge needed.

[William Brillinger]

There literally is no difference

There is 1 significant difference - the PWR-56 can be used as a RailPro Signal Repeater.

[Alan]

There literally is no difference

There is 1 significant difference - the PWR-56 can be used as a RailPro Signal Repeater.

I was referring to electrical understanding needed for success.

Yes, it is a signal repeater. But it is also outrageously expensive for a 4 amp supply. PWR56 $119 list price compared to $10 for a generic 5 amp supply. $119 would buy a 60 amp generic supply - 15 times as much power for the same money. Makes for one spendy signal repeater.

[William Brillinger]

$119 does not reflect real world pricing.

Street Price for the PWR-56 is around $90

It's $89 including shipping from PDC.
https://www.pdc.ca/rr/catalog/products/railpro-and-accessories/13

Yes, It is expensive for a power supply, but it is a "smart" power supply that provides real time feedback to the user on the handheld. You're not paying for the transformer. You're paying for a smart piece of kit that seamlessly integrates with the rest of the RailPro infrastructure.

And when you buy it as part of the RPK-1 kit it works out to about $75. If you need 2 PWR-56's you probably want another HC too.

[G8B4Life]

I don't understand all the electrical ins and outs like Tim and Alan ( I have learned a lot from you guys, thanks ).

I wish I understood as much as you think I did. Similar to what Alan has said, I just fumble my way through electronics.

$10 for a generic 5 amp supply.

I think we have to be careful here, there's generic and then there's too-generic and many would not know what to look for to differentiate between a quality generic supply that's good value and a cheap generic supply that's not designed and built so well (myself included really). It's a little apples and oranges I know but there's a reason I run a very good quality gold rated power supply in my PC (was > $200 AU, forget the exact amount) and not the cheap generic OEM supplies that I use to use. The test results on various good quality and various "cheap" OEM PC power supplies I was reading before I got the expensive supply were an eye opener!

So, yes apples and oranges comparing a bunch of LM's to the innards of a PC for power but there is still an investment to protect for RP (more so just hardware in the case of LM's as opposed to hardware and data for a PC). Saying just any generic cheap SMPS without people knowing what to look for in the SMPS features I think could - possibly - be setting them up for future heartache. It might not but I'd err on the side of caution. On that note the PWR-56, while extremely expensive at MSRP, is good for the majority; it's Rings own approved power supply (eg good for warranty claim if it was proved that the power supply fried an LM) which has the power and safety features he wants at a minimum ready to go in a package.

For the record, if I ever get the chance to build a layout the power side of things will be done very much like Alan has done with the LK&O so I'm not arguing against using SMPS's. I paid $65.00 AU for my 350 watt Mean Well power supply back in 2015. I haven't used it yet 


Bill posted while I was, so adding to post...

I think Bill has pretty much nailed it on the "smart piece of kit" is what is being paid for, though I have no doubt RE is putting a nice margin on the power supply part as well. If the price was right I'd like it if Ring would sell the PWR-56 without the power supply part, that way you could easily use a beefier SMPS like I have and then use the PWR-56 "smart" bit as part of the distribution system, like Alan did with his homemade circuit breakers but with more features.

- Tim

[Alan]

You guys are right of course. At least for the vast majority of the market.

I suppose it comes down to where you spend your money and more importantly the value received from the spend. I'll stick to my $20 power supply thank you very much. It works swell and the $160 saved makes all my bus wire and terminal blocks essentially free!

I know Ring says RP will run on a DCC layout but don't do it. You won't know the power supply temperature while you are running. <huge snarky grin>

[William Brillinger]

I'll stick to my $20 power supply thank you very much.

It's a great option, and there's nothing wrong with that choice.  It's just not an apples to apples comparison.
If I didn't want the repeater function, I'd choose the same.

[Alan]

It's just not an apples to apples comparison.

True.