Breakers

I have two power districts that are divided into four sub districts using DCC Specialties PSX Circuit Breakers, These prevents a short from shutting down a large section of the layout. They have worked very well and you can adjust the trip current. I added LED's on the panels to indicate when they trip, you can add an LED and or a buzzer for this.

The biggest issue is how many powered locomotives are on a train

Sound makes it even worse.  They recommend 5 amp breaker to keep you from having nusance shut downs due to too many locomotives on the system.  The problem is that if one locomotive hits a switch thrown the wrong way, you can burn up the wiring in the loco before you hit 5 amps to shut down the system.  If youhave a lighted pasenger train, it gets worse!  All of those lighted cars add electrical load to the system.  You need Frog Juicers to protect every switch.  You can protect multiple switches with each Juicer, but every switch needs to be protected by Frog Juicers to flip the current if the switch is hit wrong to protect your locomotives.  The 5 amps will protect the dcc system, but 5 amps is too high to protect locomotives from shorts.

One more thing, if you have extra locomotives sitting on switch leads, the dcc board in the locomotive stays powered up even when the loco is parked, sound stays active.  If you have too many locomotives on "ready tracks", you should have toggle switches to shut down the power on those tracks until you need to pull out a loco.

Power districts

I have broken my layout into 7 power districts.  

Idea is that if anything in another part of the layout shorts something, it doesn't stop the whole layout, only that segment.  Each segment has a toggle switch to cut off power to that section.  That way I can isolate each section for maintenance and trouble shooting.

What you're protecting

The NCE system (and any system worth it's salt) has internal short protection.  You don't need to worry about protecting that.

What you're protecting against is a short in one section of the layout shutting the whole layout down.  It also helps figure out where the short is - if you've got 4 power districts and only one of them is out, you have less places to look for the short than if the whole layout was a single power district.

Your NCE power supply has a

Your NCE power supply has a circuit breaker to protect the power supply, not the layout.  There is a difference.

Protecting the power supply means it shouldn’t cause a fire, or damage.  
 

Even if you only have one power district, you need a circuit breaker between the DCC system output and the layout.  If for no other reason, it will make recovery from a short faster.  When the circuit breaker restores the power, operation continues right where you left off. Almost instant.

When the circuit breaker in the power supply resets, it is just like turning the power off, then on again. You will need to go through the DCC system’s startup sequence. Depending on the system, you may also need to reacquire your loco And/or reset your function keys, etc.

GS

NCE booster output

The NCE system track output DOES have an electronic breaker, it resets automatically and fast as soon as the track short clears.  Not the same thing as the fuse or breaker built into the power supply.

The NCE power supply has a

The NCE power supply has a built in breaker. That’s upstream of the booster.  If it resets, it doesn’t make any difference if there or downstream breakers.  You want all of the other breakers to be faster than the power supply.

GS

Booster trips first

The NCE booster will trip before the breaker in the power supply.  To put it differently, if it doesn't something is very wrong - you may be using an inappropriate power supply.  Breakers and fuses for power supply protection are generally much slower than the electronic breakers on booster outputs, and assuming the power supply is adequately rated for the booster you've hooked it up to the power supply's breaker/fuse should never trip in normal operation, either if you short the booster output, or if you put a load on the booster that causes it to draw it's rated current (e.g. 5 amps from a 5 amp booster).  The only time the power supply breaker or fuse should go is if a short or fault of some sort develops inside the booster itself.

All the NCE booster's I've had have had good fast output protection that tripped when they should, and reset automatically also when they should - I've never had a power supply fuse or breaker go.

@Dave Husman & DCC Specialist Circuit Boards

Nice looking installation, Dave.

I assume those circuit boards are individual DCC Specialties circuit boards? I thought originally those boards were something like $50-60 each, but now that I look at it seems you can find them (or 4 district models) for something like $30 each?

I did see this review, https://mrr.trains.com/news-reviews/staff-reviews/2007/06/dcc-specialties-psx-circuit-breaker
that seems to make a good case for using them in lieu of just plain old 'electronic fuses'??

My first thoughts were that if the NCE power booster(s) were already equipped with 'fuse protection', why should I add duplication. But it does appear as though these DCC Specialist boards are a worthwhile investment.

Frog Juicers & Staging Locos

 You make it sound as though frog juicers are absolutely required with DCC systems,...yet I hear of many buliders that run DCC without any frog juicers,...particularly those with Peco insufrogs.

And I am not sure I understand how a frog juicer is going to protect against a switch thrown incorrectly??

I do recall reading this so I will definitely be providing cut-off power to my staging tracks.

Just a clarification - I was

Just a clarification -

I was too general in my original comment about circuit breakers when I said "depending on the system."   Knowing people other than the original poster will read this post, I'll be a bit more specific.

In the NCE line, there are several products.

As Ken pointed out - the 5 amp PH-Pro and the 5 amp PB105 boosters have electronic circuit breakers that are expected to respond within about half a second.

However, the PowerCab, and the SB5 5 amp system "reboot" the system when triggered.  Another external circuit breaker (as stated in the SB5 manual) is "strongly recommended."

NCE model names have changed over the years, so make sure you read the manual specifically for your device.

Other brands may or may not be different - so, as usual, it's import to read the manuals. 

GS

RTFM

I should have RTFM’d a bit more carefully...

By golly you’re right, I did not know that, thanks!

I spent most of my NCE using years with PB boosters, starting with the original 10 amp for m O scale layout that tripped lighting fast (not even a visible spark) if you put a screwdriver across the track, but could pump out plenty of juice under 10 amps without breaking a sweat if needed.

When I decided to give N scale another try a few years back using the 10 amp booster with it’s beefy power supply seemed like it might just be asking for trouble even with EB3’s in between, so I decided to try an SB5.  Skimmed the manual when clearly I should have read more carefully.  I’ll probably use the SB5 for the HO layout I hope to start soon, good to know I also need to dig out one of my NCE EB3’s to use with it.

(I am a bit dissapointed in the SB5 though - leaving out a proper electronic breaker feature doesn’t seem very “smart”.)

Why frog juicers?

You have two choices ... dead frogs or powered frogs.

Dead frogs kind of work, but you can still have problems in yards with lots of dead frogs in a row. Sound locos also don’t like dead frogs, they’ll cut out and tend to restart over dead frogs ... meaning do the loco startup sound sequence again, which is just plain annoying when the train is supposed to be moving. And some short wheelbase locos don’t like dead frogs.

You get better overall performance if you power the frogs. In the past that has been done with contacts that throw when you throw the points ... throw the points one way and the frog polarity changes for that route. Throw the points the other way and the polarity changes for the other route.

With live frogs using contacts tied to the turnout throw, if you forget to throw the points and you approach the turnout with the points thrown against you, you will short the track at the frog because the points are thrown wrong.

On a layout with live frogs, 99% of your layout shorts will be at the frogs when people forget to align the points correctly.

What a frog juicer does is give you the best of both worlds: live frogs so things run their best, and automatic frog polarity to always match the route of the approaching locomotive. So using frog juicers eliminates 99% of your layout shorts, saving you from equipment damage and constant cries of “who shorted the layout?” from other operators.

The one drawback of frog juicers: because the loco will no longer short at all on the frog (thereby stopping before reaching the points thrown against you), you can run a turnout with the points thrown against you and things will go on the ground at the points. If the points do not each have the same polarity as the stock rails (solid point assemblies will have both points the same polarity), then the short simply will move from the frog to the points!

So... frog juicers can dramatically reduce the shorts, that’s why they’re recommended as good short protection. However, you need to make sure the points are electrically separate and each gets power from the closure rail through a tiny jumper wire ... or use continuous points that are part of the closure rail.

Or use dead frogs and put stay alive in all your locomotives. Or for totally bullet proof performance, take the belt and suspenders approach and do both frog juicers and stay alives. The good part of the belt and suspenders approach is loco stalls will totally disappear and when combined with graphite on the track, you will find you can get flawless running performance for up to 12 months before needing any track or loco wheel cleaning.

Truly the Run like a Dream solution.

Circuit breakers and frog juicers

You need circuit breakers to break up the layout, and they are often a lot faster than the booster to shut down, especially the PSX series breakers. They also have some sort of magic sauce in them to help with start-up with a bunch of sound decoders that all want to charge up at once.

JoeF- Your piece in MRH about the belt and suspenders method has me thinking about powering frogs. In theory, locomotives that are designed properly shouldn't need powered frogs, but reality seems to still cause problems as they pass over dead frogs. I'm planning to at least drop a wire in the future so that they are easy to power later if I want to.

Speed

Having said that, if you have a reversing loop with an automate controller and possible with Frog Juicers, you may have to reprogram your circuit breakers to be slow acting to allow the automatic reverser or frog controller time to sense the short on the frog or the reversing loop and for it to fire, before the block circuit breaker fires.

A friend tried three different brands of reversers, none of them worked, then finally found out he had to reprogram the circuit breaker, and then things worked perfectly.

@Dave

About a year ago I purchased 4 auto reversers knowing I would need a few. The ones I bought were these,
PSX-AR Breakers.

I went back into my email history and found this quote by the gentleman I purchased them from,..
 

Does this mean I might run into problems with using these reversers with those PSX circuit breakers?

Is it possible I should just rely on the  PSX-AR Breakers and those breakers that are built into my NCE system??

EDITED 3/2/2021: Took out the reference to DT300 as it was not applicable designation.

That points to

a need for three, maybe four, different response times; from slowest to fastest, they are(the following presumes a booster with four districts, one of which has an autoreversing portion, and the use of frog juicers throughout the layout):

- Booster overload shutdown time (at the booster's rated output, e.g. 5A; if district settings are good, you should only ever see this when too much load is present across the layout).

- district overload shutdown time (likely, at a current that's a significant fraction of the booster output, e.g. 2A, where there may be four, or more, districts in parallel on a 5A booster)

- subdistrict autoreverser detection time (likely at a significant current, like 5A, as it's a short, but detected and reversed a lot faster than the booster or district protection)

- frog juicer detection/response time (again at a significant current, but detected and reversed even faster than the subdistrict autoreverser, to prevent the subdistrict from flipflopping) (this is only necessary if you're using "live" frogs, obviously).

Blair

Load on layout...

There was  a comment  a while back that implied the ONLY thing you needed to worry about with regards to power draw on your layout was locomotives. This is emphatically not true. 

I was helping manage a medium sized N-Trak layout once when, halfway through the second day, we started haviung problems with a PM-42 that had one section that kept dropping out, but no short was found. The same trains were running in other power districts on the same unit with no issues....  and it wouldn't happen when the train got into the power district, but only after about half of it was in, and would only recover when about half of it was pulled out by hand..... this was our first clue.

The train was a long passenger train, with an A-B-B-B-B-A set of Kato E-8 units. These locos only draw about 0.1 amp each, so they weren't the problem.

What WAS the problem was the 30 car passenger train behind them, all lit with incandescent bulbs rather than the newer LED lighting boards! (Yes, the owner knew he we risking heat damage running them on DCC...< < shrug ).

As more cars entered this power district, the total amp load went up until the PM-42 tripped. We finally diagnosed the problem with a RRAmpMeter... and discovered that one section was set at it's lowest setting, when the others were set at the next highest. Reprogramming the PM-42 to be the same on all 4 outputs fixed the issue.

In this case, the lighted cars turned out to be a bigger load than the locomotives.... sp if you're going to run lit cars (or even resistor equipped wheelsets for occupancy detection) on your layout, you have to take them into account when designing your power districts.

Or for totally bullet proof

Of course that belt and suspenders philosophy can get real expensive real fast if you have built up over the years a large roster of locos.  It's great to offer great solutions, but funding them is something else - add to that the time and skills required to install all those "suspenders" in 100-150 locos!

As it is, I am going to the expense of wiring my layout for frog juicers and also isolating staging tracks; progress is currently under way and taking a little extra time to set things up this way while laying track.

Number of Locos

Jim- Are you really running those 150 locos in operating sessions? You could focus on what you're using to operate, and then tolerate slightly less bulletproof performance in your collection when you want to run them.

If you have older PSX

If you have older PSX breakers without the trip delay config option, you can send them back to DCC Specialties for the upgrade free of charge; you will have to pay for shipping both ways.

I had issues with the combination of CVP Command station, CVP 10 amp booster and PSX circuit breakers & PSX-ARs. The main booster would trip before the ARs would reverse polarity. After getting the upgraded PSX circuit "logic" and setting the trip delay, everything works perfect. 

Safety Fuses? You must mean Safety Circuit Breakers

Fuses need to be replaced when they do their job don't they?  

Obviously not.  My earlier point needs no further comment.

Alan, how can you tell if a PSX is the older version?

Upgrades & Fuses

Upgrade reversers,
That's interesting Alan, perhaps I need to do that

Alan, how can you tell if a PSX is the older version?

Fuses
Yes Jim, perhaps I used the wrong term,

I did not notice any markings

I did not notice any markings on the board to determine the software version.

From the current on-lime PSX manual: CV55 turns on the time delay trip function. CV65 determines the amount of time delay.

If you can't change or read back CV55 or CV65, you have an older version.

After the upgrade, the software version installed on the PSX was clearly written on the board.

If I remember correctly, I contacted DCC Specialties to arrange to have the updated software installed. I removed the PSXs from the layout and mailed them. Turn around time was about a month with shipping both directions.

I'm not an expert on MRH PMs. If you would like more direct help, contact me through FB PM. It might take a few days before I respond due to my 1:1 railroad work schedule.