Thanks very much for all this good information. Very helpful.
unlike voltage, which is constant during operation, the amperage drawn depends on what the circuit is doing and you will want a power supply capable of supplying the amps required by the circuit.
you would want a power supply that is capable of supplying sufficient amps for as many locomotives you expect to operate at the same time.
passenger1955That is, if you have a power supply with high amperage, and you run locos with 1-2 amp draw each (and appropriate decoders) is there any extra danger of damaging the decoders (because the power supply has high amperage)?
the power supply has no way of know if its total current it supplies is being drawn by a single or multiple locomotives. Therefore, it has no way of limiting the current to single decoder.
passenger1955Or is damage to decoders generally related to the amperage draw from the engine on each loco?
in general, you the maximum current the decoder will need to supply is when the locomotive is blocked from moving with the wheel spinning. However, the current will be greater if the motor is prevented from turning. These are things you can measure before a decoder is installed.
a short across the rails may cause sparks and weld marks, but will not affect a decoder inside a locomotive.
greg - Philadelphia & Reading / Reading
I have had a couple of unobserved derailments that created a short circuit in which the current draw of the short did not raise to the current level that the 5 amp command station should react to. These occurances did some damage to the N gauge track and locomotive trucks by melting them requiring that they be replaced. I installed PSX circuit breakers from DCC specialties to the DCC buss, adjusting them to a safer level and a RRAMP meter to read the current draw and voltage, I still occasionally get derailments but no more melt downs. No decoder damage though.
passenger1955 Does the amperage level of your power supply create any dangers for your decoders.
Does the amperage level of your power supply create any dangers for your decoders.
Rich
Alton Junction
Every commercially available DCC booster has a fast acting circuit breaker built in. Proper function of that breaker does depend on a couple of user supplied items. First the power supply for the booster must be able to supply at minimum the voltage and current levels that the booster supplies. The internal DCC breaker won't trip if it can't get the amount of current required to exceed its trip level. e.g a 3 amp transformer can't supply enough current for an 8 amp booster's breaker to trip. but 3 amps will melt trucks and weld wheels to rail.
Second requirement is adequate wiring to supply the booster's full current and voltage to all points on your track. If a spot on you track can't pull 5 amps, it won't trip the booster's circuit breaker.
All of the above is true with DC power supply as well. Ohm's law does not change between DC and DCC.
Martin Myers
passenger1955Could someone please direct me to some place I can purchase something like the "short sensing circuit breakers with lower amp settings" described?
You haven't given us much information on what you are using.
Answering your question, Tony's Train Exchange, Litchfield Station and Streamlined Backshop all are well stocked in DCC accessories. A couple of the Kalmbach books on DCC would be money well spent.
Henry
COB Potomac & Northern
Shenandoah Valley
Hi:
Me again.
The best approach would be to decide on what command station/booster(s) you are going to use and then see what your options are regarding circuit breakers.
Just to be clear, I am still learning this stuff myself. I will defer to others for specific recommendations.
Dave
I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!
Terrific. Just the answer I needed. Thank you.
Could someone please direct me to some place I can purchase something like the "short sensing circuit breakers with lower amp settings" described?
Hi passenger1955:
A high amperage power supply is not a direct threat to your decoders, but a motor that draws too many amps definitely is. It is the motor (in other words, the draw) that primarily determines how much power is going through the decoder, not the supply. Sound adds some draw too.
Where a high amperage power supply can get nasty is if you have a derailment that shorts out the tracks. If there is no current limiting device in place then the full power of the supply will be put through the short. If you have a 10 amp power supply with no limiting devices you might very well weld the locomotive to the rails (slight exageration but the fireworks can be quite damaging, and there is definitely the possibility of frying a decoder). That is why there are devices built into the system that will detect short circuits well before anything gets welded together. The bigger power supply simply lets you run more locomotives.
Does the amperage level of your power supply create any dangers for your decoders. That is, if you have a power supply with high amperage, and you run locos with 1-2 amp draw each (and appropriate decoders) is there any extra danger of damaging the decoders (because the power supply has high amperage)? Or is damage to decoders generally related to the amperage draw from the engine on each loco?