What’s a suitable circuit breaker to use w/ the NCE starter cab sytsem? Someone suggested that the NCE 524227 (CP6) Circuit Protector would work. Any cheaper alternatives? I prefer having something reliable to warn of a short. How to wire that breaker? I thought to run feeders from the track to the breaker and another pair of wires from there to the NCE terminal.
Yes, I’ve read quite a bit about DCC and already installed decoders in the locos.
Thanks,
Lee
I believe the only cheaper alterantive is an automotive light bulb and my understanding of previous threads in the forum is that it may not prevent damage to a loco or decoder.
My alternative isn’t cheaper, it is a PSX. The Power Cab is a low power system, as opposed to a system with boosters. The PSX has to be configured for a lower amp and according to Mr DCC a normally closed push button reset is required. http://mrdccu.com/curriculum/nce/101.html
You can also wire an led into the PSX so you have a visible indicator that the cirucuit has been tripped. There is a small LED on the PSX but as that is mounted under the layout, one doesn’t always think to look at it.
They all get wired the same way DCC system to circuit breaker to track. Adding an auto reverser to a circuit breaker gets tricky because the two devices operate at different speeds. You can ask if you get to that point.
I have used the Power Cab on my home layout for many years and never found a need for a circuit breaker. The Cab protects itself if that is an issue.
Rich
Another vote for the PSX-1 circuit breaker. I have two of them because I have two power districts on my layout. While I can appreciate being on a budget, I question saving 10$ per unit in the event something happens and the fix is a lot more than 10$. Plus the trip current of the NCE unit is 1 amp. The PSX-1 has a higher trip current.
The PowerCab can only supply 1.35A, a bulb that draws less than 1.35A is needed. Any bulb drawing more than 1.35A won’t work. An 1156 auto bulb draws over 2A and won’t work.
i finally found a #211-2 T-3 festoon bulb which draws 0.97 amps. I soldered wires directly to the bulb. An alternative may be a B-6 bulb that draws 0.94 A and looks like it fits in an auto socket.
while the PowerCab will shutdown if there is short, it is difficult to track down the short because it takes several seconds for the powercab to cycle each time a short occurs.
the bulb also starts to glow if there is a larger than expected amount of current being drawn. I have some older locomotives and see this happen occasionally which means they need some maintanance.
unless the decoder is wired improperly and is the cause of the short, it cannot be damaged. It doesn’t make to sense to use a 1A circuit breaker to protect a decoder when the throttle is intended to supply enough current for more than one locomotive.
a short across the track can damage the throttle and cannot damage a decoder (the track voltage is zero). As long as the current is limited to what the throttle is designed for there can be no damage.
multiple circuit breakers or bulbs are often used to help identify which section (power district) of a layout has a short.
Yeah, the question is, do you need a separate circuit breaker at all?
An NCE command station/booster will provide the primary circuit breaker support. Any separate circuit breakers are used to protect separate power districts. If you don’t have any separate power districts on your layout, you won’t need separate circuit breaker support.
As far as curcuit breaker wiring is concerned, your bus wires, not your feeders, should provide the input and the output to the circuit breaker. Feeders from your track then connect into the ouput wires from the circuit breaker.
Rich
Do you have segregated districts? A CB on each will trip if there Is a short in one district and allow he rest of the layout to keep running.
I separate the mainline from 2 yards so 3 CB’s.
I have NCE EB1 breakers but it seems many on this forum prefer the PBX.
Our road with DCC on our HOn3 modular layout has been a learning experience. We used NCE because most of the group disliked Digitrax for various reasons. However, the module wiring doesn’t really change for any specific DCC system.
Because live frogs are essential in HOn3, shorts from running a turnout set against you happen during operations. Having the entire layout shut down every time that happened was miserable. So we mandated that a minimum each module set must have it’s own circuit breaker.
The next discovery was that all circuit breakers are not created equal. Shorts were still being passed through to the Power Pro and shutting down the whole layout because the module circuit breaker wasn’t tripping fast enough. Went back and replaced the slow-acting circuit breakers with faster ones.
The next step in our journey was that shorts were still occasionally getting passed through to the Power Pro. Because we embraced Free-mo like concepts, module sets have to be reversible end-for-end. It turns out that many DCC circuit breakers only break one leg of the track power, and not both. If we had a combination of trains spanning the module track boundary, and the two adjacent modules had circuit breakers where one broke one rail connection, and the breaker on the other module broke the other rail connection, the short could be passed through the train spanning the module gap and bypass both breakers. That one took a few tries to figure out. So now we use breakers that break both legs of the circuit.
For the OP, if you are going to add a circuit breaker in front of the Power Cab, it must act faster than the internal breaker in the Power Cab to do any good. If you are going to use mulitple breakers, and they are single leg breakers, you want to wire them all to break the same rail’s power.
just our experiences and lessons
Fred W
I just remembered this discussion if you still want a CB.
http://cs.trains.com/mrr/f/744/p/255477/2856260.aspx
Rich
[quote user=“gregc”]
The PowerCab can only supply 1.35A, a bulb that draws less than 1.35A is needed. Any bulb drawing more than 1.35A won’t work. An 1156 auto bulb draws over 2A and won’t work.
i finally found a #211-2 T-3 festoon bulb which draws 0.97 amps. I soldered wires directly to the bulb. An alternative may be a B-6 bulb that draws 0.94 A and looks like it fits in an auto socket.
while the PowerCab will shutdown if there is short, it is difficult to track down the short because it takes several seconds for the powercab to cycle each time a short occurs.
the bulb also starts to glow if there is a larger than expected amount of current being drawn. I have some older locomotives and see this happen occasionally which means they need some maintanance.
BigDaddy
I believe the only cheaper alterantive is an automotive light bulb and my understanding of previous threads in the forum is that it may not prevent damage to a loco or decoder.
unless the decoder is wired improperly and is the cause of the short, it cannot be damaged. It doesn’t make to sense to use a 1A circuit breaker to protect a decoder when the throttle is intended to supply enough current for more than one locomotive.
a short across the track can damage the throttle and cannot damage a decoder (the track voltage is zero). As long as the current is limited to what the throttle is designed for there can be no damage.
multiple circuit breakers or bulbs are often used to help identify which section (power district) of a layout has a short.
i wish Randy had explained this better.
the most likely cause of a short is when it derails, bridges between powered points and main rails, runs threw an unthrown turnout, … This is effectively a metal short across the track, reducing the track voltage and voltage to the decoder to zero which cannot result in damage to the decoder.
it’s been suggested that simply limiting the current can cause damage to the decoder. i don’t see how a properly installed decoder can cause a short unless the output wires of the decoder (function or motor) somehow becoming disconnected and touch something metallic.
i use a bulb because it is difficult for me to find a track fault when the powerCab takes several seconds to cycle after detecting a short.
Greg i would like to see Randy’s last comment in context. Could you please post a link to that thread?
I’ve given up on explaining Kirchoff’s Laws in every post [:D]
No, a derailment/running a switch short won;t hurt the decoder - or at least shouldn’t, there are plenty that seem to act up after something like that happens - probably the brains getting scrambled by the voltage spikes since a short like that is seldom instant in terms of the microcontroller’s speed. The sort of short that fries decoders will fry the decoder the instant power is applied - motor output shorted, motor output connected to a rail input, etc.
What CAN get fried are internal connections - say the link between the front truck and the rear truck if the loco derails and is crossways ont he track, so the short is flowing through the connection linking say the two left-side pickups. Or the truck sideframes - you cna find any number of pictures of melted plastic sideframes because the one truck was shorted across the rails and the metal part got hot enough to melt the plastic sideframes. Usually this is from a 5 amp or more system with no lower current limiting protection - 5 amps at 15 volts is 75 watts and 75 watts is a good bit of heat. Even the 2.1 amp 1157 bulbs - that’s over 30 watts and can still get quite warm. Under an amp with the smaller bulbs and now you’re down under 15 watts - getting to Christmas light territory and those you cna usually touch even when on for extended periods of time (if anyoen remembers the old incandescent Christmas lights, with the big bulbs, not the little twinkly light kind). Of course, there’s a tradeoff - too low a current light bulb and it will light up and suck power just when running a slightly higher current loco. Not usually a problem with most modern locos, but an old BB loco or multiple locos in MU might need a different rated bulb to allow legitimate operation while still limiting shorts.
–Randy
It’s the post right above Greg’s
–Randy
Thanks Randy, I blew right past that one.
I remember a post by Brendan in his epic layout thread. He claimed that when he talked to NCE, they said the Power Cab was designed to deal with occasional shorts, but in the long run that could be harmful to the unit.
NCE website says the same thing. The SB5 and Powercab have built in over current sensing for basic self-protection that will continuously try to reset until destroyed if left uncorrected. They do not have manual breakers that will trip or fuses that will blow.
Why would it be uncorrected? Well suppose you are running on a loop and run upstairs to get an adult beverage, then the phone rings or there is an emergency Honey-do. Meanwhile downstairs there is a derailment.
Unless it is a Proto 2000 S1/S3 with the orange wire grounded on the brush. [8o|]
Rich
[(-D][(-D][(-D]
anecdotal comments leads to confused understanding. some modelers seem willing to buy components for protection they don’t need.
when it is supplying 5A at 15V, it is the locomitives that are disspating 75W of power as kinetic energy and heat. Nothing wrong with this.
if a throttle is designed to supply 5A, it should not be damaged if there is a short and its power supply is limited to 5A. However, the throttle must now disspate 75W of heat and this may cause damage over a long period of time.
when a bulb is used, the heat is dissipated in the bulb, not the throttle.
The PowerCab uses a sense resistor to measure current. It appears that it shuts itself down when it measures an excessive amount of current. But unlike a circuit breaker, this doesn’t happen immediately. This can degrade throttle components due heat when this happens repeatedly (such as when distracted)d.
I asked for more information when someone mentioned this is a post. They said the wrong size resistors were used across the axles for occupancy detection. During continuos use, heat built up in the trucks, melting them.
Here is a short description of the pluses and minuses of using the tail light bulbs.
It is by Dick Bronson of rr-cirkits. It mentions melting truck components, as well as a risk of fire if the hot bulb contacts a flammable material. I think he is much more knowledgeable on this subject then those of us who think the bulb idea is not the best alternative.
However, for those who insist that the bulb is a good idea, he also suggests a circuit that can be used to eliminate any bulb issues.
That falls under the “motor output shorted to power input” category.
–Randy