DCC power consumption and when does enough become enough for the system

[derekdoestrains]

6 minutes ago, Pete the Elaner said:

So in summary, if you have an insufficient number of boosters & power districts, you will get poor running.

 

In that case, when planning a layout, wire it with more sections than you think you need. Give each section a separate power bus, but connect them in groups you think will be sufficient. If that works well, then great. If not, then you can just separate the power busses into smaller groups.

 

That is what I did several years ago anyway after learning from others on here.

I’m not sure that is the summery… it’s got nothing to do with running… it’s about mass start up currrent, issues around pickups in coaches bridging districts potentially becoming damaged…

 

not to mention the possibility of layout fires due to poor wiring practices… if your booster can solve the last one then I’d be amazed…

 

once the layouts up and running as long as you don’t have any long shorts (which in the perfect world never happens) your all good?

[Roy Langridge]

40 minutes ago, Pete the Elaner said:

So in summary, if you have an insufficient number of boosters & power districts, you will get poor running.

 

In that case, when planning a layout, wire it with more sections than you think you need. Give each section a separate power bus, but connect them in groups you think will be sufficient. If that works well, then great. If not, then you can just separate the power busses into smaller groups.

 

That is what I did several years ago anyway after learning from others on here.

And have a local cut-out on each district so that any shorts are limit in impact - all good sound engineering. 
 

Roy

[Dungrange]

39 minutes ago, derekdoestrains said:

… it’s about mass start up current, issues around pickups in coaches bridging districts potentially becoming damaged…

 

But surely that's just have multiple power districts and turn them on one at a time.

[melmerby]

2 hours ago, MichaelE said:

I noticed greatly improved operation when I switched from an NCE Powercab to the ESU Cab Control.

 

The NCE only puts out 2A constant with a 3A maximum. Not having anything to compare it to, I thought I didn't have enough drops. No. It was the NCE unit.

 

When I bought the ESU Cab Control and upped the amperage to 4.5A trains suddenly started running smoother without stops or slowing. Headlights and coach lights were brighter without flickering, and overall operation was actually fun again. 

 

In addition, the NCE unit will strain to put 12 volts on the track, whilst the ESU unit is adjustable for voltage and current. I am running 17VAC at the railhead @ 4.5A and operation couldn't be better.

 

All but one locomotive has sound and three or four trains are lighted.

If the current is too high for the DCC unit, the voltage shouldn't sag, the unit should trip.

I have a Z21 and I reached the 3.5A limit and the output voltage on load was still close to no load figure.

I now feed the track through a 5amp booster with the track voltage around 14v* and lights are more than bright enough and trains run up to their design speed and do not slow down.

All my stock has resistive axles and some passenger stock has lights, I only have one sound loco out of about 45 locos on the track. The voltage and running are stable.

 

*true RMS on a meter than can do it.

[MichaelE]

That was the operating voltage for the NCE Powercab. It was not sag voltage when current demand increased. 

 

When that did happen, I measured voltage as low as 10VAC RMS on the rails before the unit tripped the internal breaker.

[derekdoestrains]

1 hour ago, Dungrange said:

 

But surely that's just have multiple power districts and turn them on one at a time.

That’s exactly what could cause you to burn a coach out yes… unless you watch where you stop the set etc

[The Meerkat]

DCC is only 2 wires :)

[Dungrange]

1 hour ago, derekdoestrains said:

That’s exactly what could cause you to burn a coach out yes… unless you watch where you stop the set etc

 

Well, yes, if you stop a coach over the join between power districts, then having one switched on and the other switched off would result in the power district that's turned off being fed through the coach pick ups.  I can see that's not desirable, but surely the issue is about the design of the power districts in the first place and operator discipline.  If you make one power district the up line and another power district the down line, the only locations that these join is in the various crossovers between the up and down lines and you shouldn't really be stopping trains over these.  The same would be true for the fiddle yard - you shouldn't be stopping trains half in and half out of the fiddle yard. 

[SHMD]

12 minutes ago, The Meerkat said:

DCC is only 2 wires :)

 

Yes, bl00dy great thick ones!

 

 

Another "in-rush" current not to be ignored are the ever increasing, and number and size, of "Stay-alive" modules necessary for smooth interruption free loco running.

 

If you add a step voltage to a capacitor via a resister, (or even no resister - all the wires, tracks, and joints will add some for you), then it will initially look like a "short". All capacitors in parallel add together - so them more "Stay alive's", the longer they will look like a dead short.

 

 

Kev.

 

[derekdoestrains]

40 minutes ago, Dungrange said:

 

Well, yes, if you stop a coach over the join between power districts, then having one switched on and the other switched off would result in the power district that's turned off being fed through the coach pick ups.  I can see that's not desirable, but surely the issue is about the design of the power districts in the first place and operator discipline.  If you make one power district the up line and another power district the down line, the only locations that these join is in the various crossovers between the up and down lines and you shouldn't really be stopping trains over these.  The same would be true for the fiddle yard - you shouldn't be stopping trains half in and half out of the fiddle yard. 

But that’s the point… if you’ve got a layout that’s say… had Bachmann 37’s running with Hornby Mk2’s (for example), you’ve wired it into sections not directions (I can see why that would be handy)… along comes Mr (Or Mrs) Accurascale, mk2 nice shiney light up coaches… couple of 37’s etc… your in completely different kettle of fish from where you started…

[Ravel]

The obvious point being missed here is that the signalling system for his many layouts runs off the bus, so when the layout starts up - yes the Accura stuff is "heavy" but you also have x amount of signals running, maybe 1 or 2 not too bad, but these layouts have 30? + signals on the go, that must be adding up. I understand "they" were advised this wasn't the best idea but decided to go their own way. 

[melmerby]

2 hours ago, Ravel said:

The obvious point being missed here is that the signalling system for his many layouts runs off the bus, so when the layout starts up - yes the Accura stuff is "heavy" but you also have x amount of signals running, maybe 1 or 2 not too bad, but these layouts have 30? + signals on the go, that must be adding up. I understand "they" were advised this wasn't the best idea but decided to go their own way. 

Accessories ideally should be off a separate bus not the track feed. Most of my point decoders run off DCC system power.

Best way to do this is to feed the track via a booster and accessories straight from the DCC system.

If for some reason you get a short across the track only the booster trips, the signals & points are unaffected.

[melmerby]

5 hours ago, MichaelE said:

That was the operating voltage for the NCE Powercab. It was not sag voltage when current demand increased. 

 

When that did happen, I measured voltage as low as 10VAC RMS on the rails before the unit tripped the internal breaker.

In that case you do have voltage sag. The unit should give up to it's rated output current before it trips and the voltage should not have gone down by much.

If that's the typical NCE behaviour it's a pile of poo and should be avoided at all costs.

[25901]

8 hours ago, ERIC ALLTORQUE said:

The NCE system,theres quite a few out there and im one of them and had it for many years seems not to have the capability to produce the voltage that is preferable to run the full fat DCC layout,

I have the NCE 5amp Pro system and you can alter the output voltage to what you want from inside as long as you have a power supply that kicks out the correct voltage in the first place.

[NBL]

11 hours ago, SHMD said:

 

Yes, bl00dy great thick ones!

 

 

Another "in-rush" current not to be ignored are the ever increasing, and number and size, of "Stay-alive" modules necessary for smooth interruption free loco running.

 

If you add a step voltage to a capacitor via a resister, (or even no resister - all the wires, tracks, and joints will add some for you), then it will initially look like a "short". All capacitors in parallel add together - so them more "Stay alive's", the longer they will look like a dead short.

 

 

Kev.

 

I've mentioned this elsewhere, the wiring needs to be able to deliver the full amps that the power supply can deliver.

 

My friends layout is populated with kitbuilt locos with sound and stay-alives,10/12 on the layout at any one time on switch on, and there is never any voltage drop or sound cut outs.  There are also DCC accessory modules running off the track power bus.

 

Its the standard NCE PowerCab system, no extra power supplies, no split power sections on a 28ft long layout.  Just proper wiring.

[No Decorum]

On 21/01/2024 at 13:21, maico said:

They should consult miniatur-wunderland who have 15km of track and over 1500 DCC HO train movements a day. Energy input every 150 to 200 meters using Marklin 3-rail, Peco code 75 in the American section, and some Roco and Fleischman 2-rail track.

 

That makes NASA staff look like amateurs!

[MichaelE]

14 hours ago, melmerby said:

In that case you do have voltage sag. The unit should give up to it's rated output current before it trips and the voltage should not have gone down by much.

If that's the typical NCE behaviour it's a pile of poo and should be avoided at all costs.

 

The meager 12V was at a no-load measurement. After starting up and running more than three sound locomotives, that's when the sag occurred and current consumption started increasing.

 

Powercab is a good starter system, but it wasn't designed to operate a larger multiple sound locomotive layout with strings of lighted wagons. I used the Powercab for five years before I moved up to Cab Control and the layout grew as did the amount of rolling stock and sound locomotives.

Edited January 22 by MichaelE

[ERIC ALLTORQUE]

30 minutes ago, No Decorum said:

That makes NASA staff look like amateurs!

Still not Spacex.........roll on ship and booster test three next month.

[Bucoops]

9 minutes ago, ERIC ALLTORQUE said:

Still not Spacex.........roll on ship and booster test three next month.

 

Aw, is it 4th of July already?

[reddragon]

I have the Z21 with a twin power booster giving 3 sections in total, enough to operate all I have.

 

The highest power draw tends to be from older Hornby / Lima with well worn motors, not sound locos, even with 12 coaches / 20+ wagons in tow, but we shall see when my Mk2d's arrive!

 

12-car EMUs seem fine too.

[AndrueC]

19 hours ago, Ravel said:

The obvious point being missed here is that the signalling system for his many layouts runs off the bus, so when the layout starts up - yes the Accura stuff is "heavy" but you also have x amount of signals running, maybe 1 or 2 not too bad, but these layouts have 30? + signals on the go, that must be adding up. I understand "they" were advised this wasn't the best idea but decided to go their own way. 

I had that problem with my first layout and it wasn't that big. Eight locos, 8 turnout motor controllers (DCC Concept's Cobalt-SS) and eight LEDs powered from a DCCC Alpha Mimic. Inrush tripped the breaker. I moved the Alpha Mimic so that it was connected before the breaker and the problem was solved.

 

My current layout has the turnout controllers (far more now) on a booster circuit and LEDs on their own curcuit primarily for that reason.

 

My NCE Power Cab outputs over 13v because I upgraded the PSU. Unfortunately (?) it's also limited to 2A because my circuit breaker only offers 1, 2, 4 or 8A trips. It's not been a problem so far as the most I've seen when running four locos at the same time is .61A. That is N scale.

Edited January 22 by AndrueC

[jaym481]

1 hour ago, reddragon said:

I have the Z21 with a twin power booster giving 3 sections in total, enough to operate all I have.

That's what I have, though the double booster is track feed and the Z21 itself is accessory bus. My layout, such as it is, is more experimental than an actual layout though, so I rarely have more than two sound locos and a bunch of lit coaches on at at time. I do have an issue with a Digikeijs reverse loop module that apparently doesn't output enough to run a Hornby loco with one of their new HM7000 sound decoders installed. I need to sort that out.

[ATME]

All I can add to this topic, is that I had an issue with my AS (sound fitted) Manor’s keep alive not working. After some very quick and attentive email exchanges with AS tech support to try altering various CVs, it was agreed I should return the loco to them for inspection. Got it back a few weeks later with no difference in keep alive performance. AS tech support suggested that my DCC controller was not kicking out enough volts. Apparently ESU v5 decoders require a minimum of 14v preferably 15v. My Gaugemaster Prodigy Express shows 13.1v at the rails (DCC Concepts Alpha meter). Therefore the capacitors are not charging. Curiously though, the stay alive on my SF AS37 seems to work fine with the Prodigy Express.

I discussed this with a respected DCC systems retailer who opined that 14v minimum reason for the Manor’s keep alive not working stated by AS tech support was, er, not correct.

My knowledge on the subject is limited, so happy to be corrected.

 

[Bucoops]

8 minutes ago, ATME said:

All I can add to this topic, is that I had an issue with my AS (sound fitted) Manor’s keep alive not working. After some very quick and attentive email exchanges with AS tech support to try altering various CVs, it was agreed I should return the loco to them for inspection. Got it back a few weeks later with no difference in keep alive performance. AS tech support suggested that my DCC controller was not kicking out enough volts. Apparently ESU v5 decoders require a minimum of 14v preferably 15v. My Gaugemaster Prodigy Express shows 13.1v at the rails (DCC Concepts Alpha meter). Therefore the capacitors are not charging. Curiously though, the stay alive on my SF AS37 seems to work fine with the Prodigy Express.

I discussed this with a respected DCC systems retailer who opined that 14v minimum reason for the Manor’s keep alive not working stated by AS tech support was, er, not correct.

My knowledge on the subject is limited, so happy to be corrected.

 

 

https://www.nmra.org/sites/default/files/standards/sandrp/pdf/s-9.1_electrical_standards_for_digital_command_control_2021.pdf

 

NMRA says nominal voltage for HO is 15v.

[NIK]

33 minutes ago, Bucoops said:

 

https://www.nmra.org/sites/default/files/standards/sandrp/pdf/s-9.1_electrical_standards_for_digital_command_control_2021.pdf

 

NMRA says nominal voltage for HO is 15v.

Nominal Voltage limit not nominal voltage.