Large Scale Central

"'More power,' ya say, cap'n?"

Electronics DCC
#21

So my point on the 25 amp booster might have gotten lost (clearly not completely understood or appreciated)…

When you start getting current over about 8 amps, severe damage to loco internals and power paths is common when a short occurs, like a simple derailment.

When you get to this point in DCC (unless you REALLY have a single train that draws over 8 amps) you need to start getting more sophisticated “circuit breakers” and the only ones that really work are microprocessor driven, from DCC specialties for example, and the Zimo system I also used as an example.

Since DCC is designed to allow multiple boosters, you get in a situation where you use a large booster and have separate power districts “under” it, or you use more boosters with thier own “circuit breakers”.

Very few systems have sophisticated “circuit breakers” period, not to mention the super high amperage ones.

SoI was making the point that I’ve really never met anyone that needed more than 10 amps per power district, and NEVER found a common complaint the needed over 10 amps per power district.

It’s great that there is a super large unit out there, but it’s “stupid” and will require “smart” electronics working with it, and yet that combination will not yield the sophistication of a system like Zimo that analyzes the characteristics of the overload condition and can “trip the breaker” at significantly less than the maximum current rating when it “knows” there is a short.

I have really seen the difference between my NCE system and my Zimo system in what they detect and how they protect my locos. Sure the Zimo is 2 to3 times the cost… but how much damage am I avoiding over time?

Tough to figure out, different for different people, but in the end you get what you pay for, just not everyone realizes these fine points.

Greg

#22

Cliff Jennings said:

Here’s my question, would this 30A booster, with the needed whatever to split / limit it to districts, be less expensive and more functional than 3 NCE/Meanwell 10A booster setups?

The 25 amp (30A peak) booster in this case is less than $200, but for the sake of argument, let’s call it $200 due to the exchange rate. If you want to limit the current going to various districts, you’ll need circuit breakers. DCC Specialties has a 4-block circuit breaker board for $180 MSRP ($135 on the street). 3-block boards are cheaper, and 2-block boards cheaper still, but figure $35 per block street price. There may be other boards, but this is what turned up on a search. (Again, I’m primarily deadrail DCC, so boosters and power districts aren’t things I usually worry about.) You’ll also need an external power supply. I found a Mean Well supply for $169, since they seem to be well-respected.

Let’s then look at the cost for a 30-amp total system. For example 1, we’ll talk about this 30-amp (peak) booster divided into 3 districts with circuit breaker protection for each district. For the other, we’ll use 3 NCE 10-amp boosters.

Booster - $200

Power supply - $169 (Mean Well)

Circuit breakers - $104 (DCC Specialties 3 districts on one board)

Total price - $473

(If you wanted to go with a 25-amp, 24-volt power supply, you can lop nearly $100 off the cost of the power supply.)

For the NCE system, you’re going to need one 10-amp booster plus a power supply for each individual district. (Mean Well, $51)

Booster $211 per district

Power supply - $51 per district, or you could connect the three boosters in parallel to one 30-amp power supply ($169)

Total price for three districts - $786 - $802 depending on power supply choice

You’re paying close to twice as much for the NCE-booster-based system. What I can’t tell you (because I don’t do track powered DCC) is whether there is an advantage to using the NCE 10-amp booster straight to the track as opposed to using the DCC Specialties (or other) circuit breaker. From the manual, the DCC Specialities breaker sounds like it does more than just monitor the current going through it, being able to do block detection and can tell “if the overload is a real short or due to excessive capacitance in sound decoders or lighted passenger cars.” (quote from the manual)

Later,

K

#23

Are there any “rules” for figuring out power districts?

#24

Once you figure out your worst case power for your trains, then you figure how many can be in a power district at the same time… set the power districts so you don’t exceed your capacity.

Suppose all your trains are 5 amps max… and you have decided to use 10 amp boosters… then set the “length” of a power district so that you would never have more than 2 trains in the district at once.

In my case, my outer main is a single circuit, but it will be a 20 amp Zimo one. The inner main is much smaller so it will be fine with an 8 amp power district and the remaining 12 amps (second zimo booster) will handle the switchyard since there could be a lot of locos idling and running as well as mainline trains coming in and out.

so 3 power districts, 20 amp, 12 amp, 8 amp, using 2 Zimo command stations/boosters with very advanced short circuit analysis and detection. There is a reversing loop in the switchyard and that is handled by a DCC specialities autoreverser/circuit breaker.

The DCC specialities units are smarter than the normal stupid boosters, but they don’t have the analytical horsepower to match the Zimo, which runs Linux and has many settings you can adjust.

So that’s what I am using… overkill? Not from my point of view of my priorities… low maintenance, stuff works all the time… rather spend a few more $$ to avoid repairing locos.

Greg

#25

Thanks Kevin and Greg for the further information, it’s all very helpful!

#26

On another note, I would question the speed of disconnect when there is a short.

Fuses melt, but take time and this is in milli seconds if I remember correctly.

Breakers take time to move the points and also take milliseconds.

Thermal units also take time to warm up and create a high resistance.

Electronic sensors take microseconds and are faster than fuses and breakers.

#27

True… I was using the term “circuit breakers” in quotes because that term normally means a mechanical device to me, and all the ones we have been talking about are solid state, and some microprocessor controlled.

Also, certain systems have boosters that communicate back to the command station and some have some sophisticated logic, others not.

For example the DCC specialities units are smarter that the non-smart ones, but they don’t communicate anything to the command station. The NCE system does have a basic command structure between the booster and the command station… the Zimo communicates all over the place ha ha!

Greg