Several questions about DC engines and decoder equipped engines sitting on a DCC layout. Could not find an answer via Goggle. Trying to make sure I do not fall into some trap by bad assumptions.
1) Does a decoder equipped engine sitting idle (turned off via throttle) on a layout consume any power? I would not expect it to. I know the decoder is always "alive" so it can accept commands but that draw should be minimal (aka no issue)
2) If a decoder equipped engine is thought to be "off" but is actually at a very low throttle setting (but not moving), I am assuming it will be drawing some power. Is this situation harmful to decoder or engine motor?
3) Related to #2 above. When DCC system is turned OFF, does the engine in #2 default to zero speed when that DCC system is powered back up? I would assume it would.
4) If a DC engine is sitting on a DCC layout but no throttle is trying to command it via the 00 address, is it drawing power? It this situation harmful to the DC engine over a prolonged period?
My bottom line is that I am trying to determine the good/bad of any engine sitting idle on an active track for an extended period because that engine has no near term assignment. I would like to be able to leave my fleet of decoder engines on the track all the time then call some (not all) into action depending on requirements of each operating session.
Paul D
N scale Washita and Santa Fe RailroadSouthern Oklahoma circa late 70's
good question, I have my popcorn waiting and watchin
Henry
COB Potomac & Northern
Shenandoah Valley
I'm sorry, but switch those DC locos to DCC or retire them.
Bear "It's all about having fun."
bearman I'm sorry, but switch those DC locos to DCC or retire them.
I have a few that are just static display sitting around an engine shed. They will not get DCC. Perhaps I will just open them up and snip some wires.
I agree with bearman.
1) A DCC decoder equipped loco. sitting idle, sound turned off, and headlight off, does draw current. One loco. I have draws .02 amps. and another draws .04 amps. others I have may draw more.
3) If loco. is moving and System is shut down (short, power outage, E-stop) the loco. will not move when System is powered back up untill it is acquired (direction change or throttle change).
RR_Mel DCC has around 16 volts square wave (AC) on the rails continuously. Can’t put a DC locomotive on a DCC track. Mel Modeling the early to mid 1950s SP in HO scale since 1951 My Model Railroad http://melvineperry.blogspot.com/ Bakersfield, California I'm beginning to realize that aging is not for wimps.
If I set my thottle to adderss '0000', I can run DC locos. on DCC track, all DC locos. will respond at the same time and move in the same direction, but at idle or moving, with a hissing/buzzing noise. I think it's been said in MR that this is not good for the DC (non decoder) motor.
1. Minimal power consumed
2. It's not moving at all. There is 0 Watts to the motor. No harm will be done. Only the decoder will be on or sound playing through the decoder. Again this is minimal. Todays engines rarely exceed 1/2 amp with a can motor running full speed. Sitting still it's just peanuts in terms of power.
3. When the DCC system is off, the decoder is dead. What it does when powered back up depends on the DCC system in question. For example a DCS51 will resume to what the throttle is set at.
4. A DC engine sitting still (0 speed) on a live layout WILL EVENTUALLY damage the motor. It is constantly consuming power through an alternating current. You will hear the motor "buzz" as it sits still. This will eventually cause the motor windings and commutators to overheat. This has been demonstrated here in these forums as an experiment on athearn blue boxes, which are very hardy motors.
Don - Specializing in layout DC->DCC conversions
Modeling C&O transition era and steel industries There's Nothing Like Big Steam!
PC101 RR_Mel DCC has around 16 volts square wave (AC) on the rails continuously. Can’t put a DC locomotive on a DCC track. Mel Modeling the early to mid 1950s SP in HO scale since 1951 My Model Railroad http://melvineperry.blogspot.com/ Bakersfield, California I'm beginning to realize that aging is not for wimps. If I set my thottle to '0000', I can run DC locos. on DCC track, but with a hissing noise. I think it's been said in MR that the DC motor will heat up.
If I set my thottle to '0000', I can run DC locos. on DCC track, but with a hissing noise. I think it's been said in MR that the DC motor will heat up.
PED1) Does a decoder equipped engine sitting idle (turned off via throttle) on a layout consume any power? I would not expect it to. I know the decoder is always "alive" so it can accept commands but that draw should be minimal (aka no issue)
yes, the decoder is drawing enough current to power the processor but significantly less than if it were driving the motor
PED2) If a decoder equipped engine is thought to be "off" but is actually at a very low throttle setting (but not moving), I am assuming it will be drawing some power. Is this situation harmful to decoder or engine motor?
a motor that is not turning produces no back EMF (voltage produced by wire passing thru a magnetic field) to resist the flow of current. A small amount of voltage applied to a non-turning motor will only be limited by wire resistance dissipated as heat.
however, many decoders monitor BEMF and will increase the voltage until the motor turns at a speed proportional to the throttle setting. I've heard locos cycling as the decoder increases voltage and then aborts because it measures no BEMF if the motor won't turn.
PED3) Related to #2 above. When DCC system is turned OFF, does the engine in #2 default to zero speed when that DCC system is powered back up? I would assume it would.
as far as I know, a command station does not remember previous thottle settings after losing power.
A command station will only send commands to decoders that it is aware of. After power up, a decoder should set the motor voltage to zero until the command station sends it a command.
PED4) If a DC engine is sitting on a DCC layout but no throttle is trying to command it via the 00 address, is it drawing power? It this situation harmful to the DC engine over a prolonged period?
A DC motor sees an alternating voltage of ~14V, effectively full power in one direction then the opposite direction. The non-turning armature produces no back EMF and current is limited by wire resistance resulting in heat.
The motor will get hot, wire insulation can melt producing a short, damaging the motor.
PEDMy bottom line is that I am trying to determine the good/bad of any engine sitting idle on an active track for an extended period because that engine has no near term assignment. I would like to be able to leave my fleet of decoder engines on the track all the time then call some (not all) into action depending on requirements of each operating session.
this is typycal of most layouts. It's one of the benefits of DCC, that a loco can sit on a powered track but not be commanded to move until needed.
greg - Philadelphia & Reading / Reading
Number 1. Yes, the decoder will draw minimal power even while sitting idle. A couple of miliamps. Sound decoders may draw a little more.
Number 2. Yes the draw will be a little higher than idle. Depends on which speed step the address is set. No damage to engine as the motor is getting rectified DC from the decoder.
Number 3. Maybe. If only track power is turned off and the command station is still active the decoder and engine will return to its previous speed and direction and functions when track power is turned on again. If the command station is turned off, you will most l9ikely need to re-aquire the engine and start from zero speed.
Number 4. Yes it is drawing power and probably shortening the life of the engine. You will hear it buzzing which is actually the motor switching direction thousands of times because it is getting AC instead of DC power. Best to remove the engine, turn that track off if possible, or "cut some wires" if possible. It won't hurt your DCC equipment but it will be drawing current and the noise from the engine(s) will most likely get irritating. Until they burn up and no loger buzz.
Martin Myers
Common sense says the DC loco sitting on a track with DCC applied to the track is drawing power even if the loco is not moving. You can hear the buzz. The armature is vibrating at the DCC frequency and getting hotter the longer it sits there. Some years ago I measured the temperature with an infra red temperature scanner. Two points get quite hot. Right where the two brushes contact the commutator. When the armature is rotating, the temperature drops. I measured open frame and can motors. Any infra red temperature scanner can do this and sense right through the can motor shell.
Anyone can easily do this test.
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
Thanks for all the responses. This makes me more confortable about letting DCC enginies sit idle on my layout even when not in current use. I will not leave DC loco's sitting on my track as static display unless they have been neutered.
Wouldn't it just be easier to put an on/off switch on the track where you want to park engines? I did and I have no problems.
Roger Hensley= ECI Railroad - http://madisonrails.railfan.net/eci/eci_new.html == Railroads of Madison County - http://madisonrails.railfan.net/ =
easier than what? sorry