Agreed, there is a whole lot more to it, (back EMF, etc.) but my point is that at a lower voltage the power supply might be able to provide the necesary current to run 3 units, whereas at a higher voltage that can run two units, the third one presents an overload condition.
Actually, if you could get the engines running the increased speed might create enough back EMF to reduce the current to an acceptable level for the power supply, but the startup current is exceeding the supply's capability.
Semper Vaporo
Pkgs.
Bob Nelson
I think this is simply Electricity 101...
I don't know anything about the units you are running or your power supply but lets just apply some numbers that fit Ohm's Law...
Each unit draws a current that is proportional to the voltage applied.
If you apply one Volt to one unit it will draw a certain number of Amps. You apply 2 Volts and it will draw twice as many Amps. Just for grins (and I must point out that these numbers are just for example and do NOT really represent your true situtation):
Say you apply 1.0 Volt and it draws 0.1 Amp, you increase the Voltage to 2.0 Volts it will draw 0.2 Amps. Apply 10.0 Volts and it will draw 1.0 Amps.
Now if you put two units on the circuit EACH will be drawing the same current from the same Voltage. Thus, you apply 1.0 Volt, they each draw 0.1 Amps, thus the total current draw is 0.2 Amps. Apply 10.0 Volts and the total current draw will be 2.0 Amps.
If your power supply can supply 2.0 Amps, then you have no problem.
BUT, if you put a thrid unit on the circuit at 10.0 Volts, then the total current draw will be 3.0 Amps and if your power supply has a fuse (or circuit breaker) that trips at 2.5 Amps, then the circuit will shut off to protect the power supply from overheating.
Note that 3 units could run at just 5.0 Volts because each would be drawing just 0.5 Amps making the total current to be 3 times that, or 1.5 Amps, which is below the trip point of the power supply.
Ain't it just that simple? Or am I missing something?
Very Interesting.....and I do not have a clue!
Jim H
lionroar88 wrote: Sir James...OK... that I can do without spending too much time on it! LOL!---One more question... what is the proper behavior for Williams engines when you first power up... should the engine move (as a PW engine would), or should it sit in neutral - like a TMCC engine would? I assume it would be the PW behavior?
Sir James...OK... that I can do without spending too much time on it! LOL!---One more question... what is the proper behavior for Williams engines when you first power up... should the engine move (as a PW engine would), or should it sit in neutral - like a TMCC engine would? I assume it would be the PW behavior?
Forward on power-up,B.
If the "ZW" is using a high-frequency chopping technique, its output is probably virtually sinusoidal and the meter would work. But, if it is using phase control, like the CW80, an ammeter on its input would have the same problem with the waveform as an ammeter at the output.
An ordinary AC ammeter on the sinusoidal output of a transformer or "transformer" will read correctly only if the load is linear. If these "bricks" are something like phase-control modules meant to be fed from a true transformer, it won't work to put the ammeter between the transformer and the "brick", since the "brick" will draw non-sinusoidal current from the transformer, just as a CW80 draws non-sinusoidal current from the power line.
You can of course use an ordinary ammeter if you want, as a rough indicator, if you don't mind the inaccuracy. However, what you really need is a true-RMS ammeter. Which will not come cheap.
Questions whose answers depend on what's inside a modern "ZW" keep popping up. Is there anyone who has any technical information about them? Or about the "bricks" or whatever else is used with them?
lionelsoni wrote:Those meters almost certainly are accurate only with a sinusoidal waveform, such as you would have with pre-modern "transformers", which are true transformers. They would not be accurate with a CW80. I don't know about a modern "ZW", but I am not optimistic.
Perhaps if you put them on the inlet to the ZW (outlet of the bricks?). Or maybe you have a friend with an MTH or ????? unit. Some of the large transformers have amp meters.
Will these work for measuring AMPs from a Modern ZW, PW ZW, or PW KW?http://www.action-electronics.com/panelmeters.htm#Digital
I'm assuming I would only be able to use the Analog AC versions?
lionelsoni wrote: Bad connections and too-small wire would only decrease the current drawn; so I doubt that's the problem. I don't know anything about the insides of the modern "ZW'; so I won't try to explain its behavior.(That wire you're using is safe for only about 4 amperes. It won't solve you problem, but I would upgrade it to whatever your transformer can put out, if you can figure that out. Fourteen AWG is good for 15 amperes.)
Bad connections and too-small wire would only decrease the current drawn; so I doubt that's the problem. I don't know anything about the insides of the modern "ZW'; so I won't try to explain its behavior.
(That wire you're using is safe for only about 4 amperes. It won't solve you problem, but I would upgrade it to whatever your transformer can put out, if you can figure that out. Fourteen AWG is good for 15 amperes.)
"IT's GOOD TO BE THE KING",by Mel Brooks
Charter Member- Tardis Train Crew (TTC) - Detroit3railers- Detroit Historical society Glancy Modular trains- Charter member BTTS
Morning Brent, it's hard to help without being there. Something is drawing to much current a newer zw should handle what you describe but I don't have one to compare(I have 2 pw). power every thing up sit in neut. then run you hand around the track feeling for hot spots. you may have a bad connection using atlas track connectors.
God bless TCA 05-58541 Benefactor Member of the NRA, Member of the American Legion, Retired Boss Hog of Roseyville , KC&D Qualified
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