Anybody have a definitive answer on whether pulse power using n scale locomotives damages motors?
I have a MRC Tech 2 power pack and use dc
west willow and laurel Anybody have a definitive answer on whether pulse power using n scale locomotives damages motors? I have a MRC Tech 2 power pack and use dc
Overheating is what damages motors. Overheating can be caused by overloading (primary cause) and some forms of pulse power.
Open frame motors (older locomotives) have more air for cooling available to them, but are also less efficient. Lower efficiency means more heat generated for the same load. Can motors (most common type of motor in today's locomotives) are considerably more efficient due to improved magnets, and shaping of magnets around the armature. These generally run cooler than open frame motors - unless overloaded. Because of the shaped magnets, there is less cogging in a can motor, and therefore less need for pulse power for slow speed running.
Coreless motors do away with the iron armature, and therefore lose the ability of the metal mass to dissipate heat. However, their high efficiency prevents heat buildup in normal use. Coreless motors are the most susceptible to overheating and resulting damage. Coreless motors are much more expensive than cans, and therefore not found in mainstream RTR locomotives.
The MRC Tech power packs are specifically made to have a relatively gentle pulse, and use pulse suppression at higher voltages. I have not heard of (or experienced) MRC pulse power in the Tech series power packs causing overheating, even with coreless motors. The trade-off is loss of ultimate tie-creeping capability. But do you really want to operate at less than 2 scale MPH (nearly 60 seconds to travel 1 foot in N) for extended periods?
Strict PWM at low frequencies and high voltages (12 volt plus pulses at 60Hz or so) can damage coreless motors. Which is why almost all DCC decoders use PWM at frequencies above 1KHz.
my thoughts, your choices
Fred W
I'm using a MRC tech 2 2500, my engines get a little warm I've been assessing other powerpacks that I can use that will not have this problem.
SP&S modeler, 1960's give or take a decade or two for some equipment.
http://www.youtube.com/user/SGTDUPREY?feature=guide
Gary DuPrey
N scale model railroader
Back when I was in N scale, I had a Tech II 1500 as my power pack. Never had any problems with any motors being damaged.
Part of this "damage by pulse pwoer" goes back to the early days when it was discoverd that by cutting a jumper on the typical selenium rectifier stack, you could get a pulse output tot he track and it made your locos start up better. At full throttle though this was not particularly desireable, so along came the addition of a toggle switch to turn this "pulse" power on and off. Further experimentation showed that different frequencies and amplitudes of pulses made different motors perform better, so along came fancy power packs that has pulse width and pulse amplitude adjustments, as well as the pulse on/of.
By the time of the MRC Tech II series, the pulse was automatic - it was there at low throttle and disappeared at full speed. No harm will come to your locos using any reasonably modern (Tech II is over 30 years old) power pack. The really old ones won;t control N scale motors anyway, they would be of rheostat type and unless it was made since N scale appeared in the early 60's AND was one specified as N (MRC models had an 'N' in the name, like the 550 was an HO pack and the 550N was the N scale version) it won't be able to control N scale motors or most any modern HO motor due to the rheostat being the wrong resistance. Transistor packs like the Tech II work on any scale because they don;t rely on a rheostat to drop voltage, which varies with the current draw of the motor.
The only kind of motors that might be harmed by pulse power are coreless motors, and you won;t find those in any mass market locomotives, unless a previous owner swapped out the motor. They are exceedinly rare even in brass locos, mainly due to the cost (and please I don;t want to hear from the ONE person who remotored their entire fleet with coreless motors so they have over 50 of them ).
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Burlington Northern #24 I'm using a MRC tech 2 2500, my engines get a little warm I've been assessing other powerpacks that I can use that will not have this problem.
I doubt very much the Tech 2 2500 is the cause. Under continous running, a motor should get warm - but not hot to the touch. I use a Tech 2 2500 myself to run an HOn3 2-6-0 with a coreless motor sealed in the tender - no issues there.
More likely cause of overheating is excessive loading on the motor - either from too much friction in the drive or too many cars being pulled. Best way to check is with an ammeter or a multimeter set to read the current drawn by the engine. Running by itself, if the engine is drawing more than 0.3 amps (300 ma), there is too much friction. Train load should never drive an N scale engine above 0.5 amps. Ideally, currents on a good N loco would be half the amounts I cited.
Friction could come from gears not being in proper mesh; hardened grease or lint or hairs in the gears; motor not properly aligned with gears; locomotive axle bearings with gunk in them; etc.
fwright Burlington Northern #24 I'm using a MRC tech 2 2500, my engines get a little warm I've been assessing other powerpacks that I can use that will not have this problem. I doubt very much the Tech 2 2500 is the cause. Under continous running, a motor should get warm - but not hot to the touch. I use a Tech 2 2500 myself to run an HOn3 2-6-0 with a coreless motor sealed in the tender - no issues there. More likely cause of overheating is excessive loading on the motor - either from too much friction in the drive or too many cars being pulled. Best way to check is with an ammeter or a multimeter set to read the current drawn by the engine. Running by itself, if the engine is drawing more than 0.3 amps (300 ma), there is too much friction. Train load should never drive an N scale engine above 0.5 amps. Ideally, currents on a good N loco would be half the amounts I cited. Friction could come from gears not being in proper mesh; hardened grease or lint or hairs in the gears; motor not properly aligned with gears; locomotive axle bearings with gunk in them; etc. my thoughts, your choices Fred W
Warm is perfectly normal, especially after running them for any length of time. Hot is bad.
next time I run my RS1 I'll time it and see how long it is until it gets warm, my life likes get extremely hot. my kato's and atlas' get warm even the ones that don't run as much.