My train runs too fast

[lionelsoni]

Okay, here goes.

Many folks are familiar with Ohm's law, which says that voltage and current are proportional in a resistor, with the constant of proportionality being what we call the resistance. Resistance is measured in ohms. An ohm is one volt per ampere. "Law" is probably too strong a word for Ohm's law. All it really does is define what a resistor is, that is, a component that follows Ohm's law. Lots of electrical devices don't follow Ohm's law.

If you're dealing with resistors and DC voltage and current, there are no complications. But when you start using AC, it begins to get interesting. Ohm's law still applies; but the voltage and therefore the current are fluctuating all over the place. The power that was dissipated in the resistor was equal to the voltage multiplied by the current and was constant. Now it is going between zero and some high positive value 120 times per second. Note that it is always positive, since, when the voltage becomes negative, the current does also; and the product of two negative numbers is positive.

This is where RMS voltage comes in. It means "root mean square". The RMS value of an AC voltage is the equivalent DC voltage which would produce the same heating in a resistor as the AC voltage in question. This is a trick to allow AC power calculations to be done the same way as DC ones, by multiplying the voltage and current. For AC, you multiply the RMS voltage by the RMS current. The RMS current is the RMS voltage divided by the resistance, just as with DC. So we get the familiar equations for power:

P = E*A = E*E/R = I*I*R

where P is power (watts), E is electromotive force, that is, voltage (volts), and I is current (amperes).

Note that this scheme is invalid if the load is not a resistor. It is also invalid for AC if the voltages and currents are not expressed in RMS volts and amperes. It is valid for nonsinusoidal waveforms.

About the only resistive loads we have in toy trains are smoke-generator heaters and incandescent lamps. The lamps are only a sort of honorary resistor, since their resistance varies with voltage and current. It is however pretty much constant over the 8-millisecond cycle of our AC power.

So it is only approximately true that we can calculate the power load on our transformers by multiplying voltage by current. It would be very difficult to do the calculation exactly; so go ahead and do it that way, then throw in a little extra power rating just to be safe. You can add up power or current, whichever you like. Just be sure to convert one to the other with the voltage value that you will be using. For example, if you know that two locomotives draw 2 and 3 amperes respectively at 16 volts, and that is the highest voltage you will be running them at, multiply 5 by 16 and put it down for 80 watts; or multiply 2 and 3 separately by 16 and add 32 and 48. Then get a 100 watt transformer.

I was referring to the type Z, because its high output voltage, a legacy from prewar times, makes it probably the only postwar transformer that could be adapted for use all the way down to zero volts. Electrically it is not so different from the ZW, which, in addition to a more modern voltage range, has whistle controls added to two of its outputs. Of course the ZW looks very different. I would not have one for that reason alone, since I have always thought they looked ridiculous. Chacun a son goust.

[lionelsoni]

I'd be happy to; but what is the question?

[Anonymous]

okiechoochoo,

I only have the transformers that I listed in the initial post on this thread -- no MTH, sorry to say.

In my experience, it is easier to find specifications for amps for things like train motors than it is for watts. Another reason I use amps is to help me pick the right fuse for a given job.

With an old-fashioned transformer operating at 18 volts (full throttle,) 80 watts would imply about 4.4 amps, but with all this new modern electronics with the constant voltages and "chopped" waveforms, I haven't a clue as to what's going on.

With my CW-80, at high throttle settings this morning, the overload lamp began to flicker at the relatively heavy load I was running, but it didn't cut back the power, and my 5 amp fuse didn't blow either. I'd say it worked OK, but clearly we were approaching it's design limits. (It did NOT get hot.)

I fuse my main transformers thusly: CW-80 and 1033 -- 5 amps. KW --7; ZW -- 10, although the ZW's original circuit breakers were rated at 15, I think. I tend to run things conservatively. (Fast-blow fuses, thank you very much.)

Here are some examples* of power requirements in watts, from the old days:

0-27 locomotive, no whistle, 15 -20
0 gauge large locomotive with whistle 35-40
Operating Accessories 15
Each 18 volt lamp 5

*Source: Complete Service Manual for Lionel Trains, by K-line, 1982, p. 628.

The idea was simply to add up these values up when planning your "dream layout" and that would be a guideline for what wattage transformer you needed.

Applying the more conservative (lower) values to today's experiment, I'd guess the CW-80 was driving those old growlers and the lamps with something on the order of 94 watts.

In reality, every operator that I have known has longed for more power rather than less, and I'll admit I like having my hands on the throttles of an old postwar ZW: vroom, vroom!

Maybe Bob Nelson (lionelsoni) or someone else on this forum could go into this in more detail.

Thanks for the kind words.

wolverine49

[okiechoochoo]

Thanks a lot for that information. I will certainly read your thread on problems with the CW80. It is good to know it will pull the consist you tested and I like the slow speed performance. However, I have also been told to look at the MTH Z1000 which, of course, is slightly more powerful. You don't happen to have one of those do you?[:)] What I am wondering is what the low end voltage range is on the Z1000. Also, I am an old postwar guy so I have always figured in amps but I guess I need to start using wattage on these new transformers. Do you happen to know the wattage of this new stuff, such as can motors and light bulbs or maybe how much amp a 100 watts makes? Thanks for all your help.

[Anonymous]

okiechoochoo,

You might want to research the CW-80 on this and the other forum. Please do me the honor of starting with my long post in the thread of 28 March '06 "Problems with Lionel CW-80 transformers" on this forum.

To try to give an empirical (rather than speculative) answer to your question, this morning I set up a Lionel post-war 2344 dual horizontal-motor F-3 from 1950, pulling 4 Williams illuminated passenger cars (6260, 6262, 6263, 6265), four illuminated switches, two illuminated lockons, running on about 30 feet of track, and the famous "twenty-five sacks of mail."

After a little lubrication (of the rolling stock) the CW-80 drove them just fine. At full throttle, I couldn't quite get them to derail (MagneTraction working well) but it was flying. Low speed performance was excellent -- much better than my ZW will do, although definitely NOT reaching the impressive state-of-the-art performance of certain modern electronic controllers where you're not absolutely sure it's moving.

(Prior to doing a little lubing of the pickup rollers on two cars, and correcting a dragging wire, the CW-80's self-protective circuitry began to "get a little nervous" as manifested by occasional flickering. (As I read the owner's manual, this is "normal" but it does indicate that momentary overloads are occurring.)

After the lubricating, all was well and the warning lamp did not signal any more "cautions."

Conclusion: The CW-80 has sufficient power* to run the consist specified in the question -- but not by a large margin -- at least with postwar equipment. It would NOT be my first choice to go out and purchase for this setup. By the same token, inasmuch as I already own a CW-80, and I particularly liked the low-speed performance, I wouldn't change it out either.

For locos with modern, efficient dual can motors it should do fine but keep and eye on the amps required by the total load.

Note: the CW-80 actually has a good deal of power.* It is my opinion that some folks think it doesn't because the throttle-power ramps up gradually rather than instantaneously. Presumably this gradual application of power is intended to reduce the number of rubber tires that get chewed up and thrown off during jackrabbit starts. In any case, it is not a "defect" but a "feature." Some operator's don't like it. It is one of the "quirks" and takes a little getting used to. I think it makes it a little more difficult to teach children to operate it, because the feedback they get when they move the throttle handle is not as obvious as with other transformers, and they tend to overcompensate.

*Postwar transformers were rated by their imput, which must be multiplied by about 0.67 to get the power output. Thus a 1033, although rated at 90 watts, actually could only deliver about 61 watts to the track. With the CW-80, along with most modern transformers, the claimed output (80 watts) is what you get -- so I have been informed. And to get the zero to five volt range on a 1033, you are limited to about 11 volts on the top end. With the CW-80 you get about 1 to 18 volts continuously variable.

I sincerely hope this post provides more light than heat.

wolverine49

[thor]

You could always use that diode trick to drop your ZW voltage a tad, assuming your locos will run below 5 volts. My can motored 4-4-2 will run as low as 2 volts but none of the Pullmor motors show much interest below 6 although once rolling they can be persuaded to run on less.

I'm still looking for a decent power supply too.

[okiechoochoo]

I thougth the CW80 transformer had all kinds of problems. Is this not true? Is it powerful enough to run a twin motored diesel and four lighted aluminum passenger cars and operate bells and horns. That is probably the largest current draw I will be running. Also, what is needed to operate a TPC300. Does one need a transformer or just the power brick. What else does it take. Does this allow voltages down to less that 5V comparable to the postwar 1033. Thanks

[Anonymous]

okiechoochoo,

Are you suggesting that there might be something that the 1033 couldn't do that a CW-80 could? Heresy! Shame on you.

One way would be to buy a Lionel Sound Activation Button, item number 6-5906, for around 15 bucks. With one of them, and a 1033, you could enjoy either whistle/horn or bell, simply by pushing the correct button (or lever.)

wolverine49

[lionelsoni]

Any of the postwar transformers can be modified by bypassing the fixed winding. This is particularly practical with the type Zs, since they go up to about 25 volts with the winding in place. I had mine that way for a while, but put it back to accommodate the low gearing on the 773.

[okiechoochoo]

Just thought of a question. If one is running Williams with a 1033 transformer how do you operate the bell?

[okiechoochoo]

Can anyone provide similar output statistics on modern transformers such as MRC, MTH Z750 and MTH Z4000 as well as the new LIonel ZW or Powerhouse with TPC 300/400?

[Anonymous]

Thank you wolverine . [^][^][:)] very informative............Felix

[Anonymous]

This may help explain why.

(This issue was raised in part on another post this morning.)

I ran some informal tests this morning, using an inexpensive analog voltmeter and reading it as best I could. Except as noted, I measured the transformer outputs ("hot" post to common) without any load. The numbers are the minimum volts that the device could put out before dropping to zero.

Postwar ZW 250 A = 7.5, B = 7.2, C = 7.0, D = 7.0
Postwar ZW 275 A = 7.5, B = 7.5, C = 7.4, D = 7.3
Postwar KW A = 7.2, B = 7.2
Postwar 1032 A = 5, B = approx 1
Postwar 1033 A = 5, B = approx 1
Marx #329 A = 6.2
CW-80* (1) A = approx 1
CW-80* (2) A = approx 1

Above these minimums, the throttles would all increase relatively smoothly, although the precision of the resulting incremental speed increases varied from one transformer to another. (The ZW's were a tad coarser than the CW-80s, for example.) These results should be no surprise to anyone who has ever looked inside a postwar transformer, most of which do not put anything out less than 5 volts, at best.

These tests were conducted with the transformers operating a zero load, except for the CW-80's* which were powering 2 small yard lamps in order to read sensibly.

The significance is that my sole Williams diesel, for example, unmodified from the way it was manufactured, could run smoothly and nicely, pulling 3 freight cars and an illuminated caboose, at realistic scale speeds. Similarly (once warmed up) my venerable old 2332 GG1 from 1948 gave comparable results. (She is one stately old lady!)

Neither, however could approach the kinds of low speed, non-stalling performance of some of the fancy electronic throttle systems that I've seen; but they wouldn't go flying off the ping-pong table either.

Coupling/uncoupling operations could be carried out without doing any damage. The efficient Williams, and others of my more modern locomotives, cannot be slowed down as far as I would like on the postwar transformers, other than the 1033 types, but they did quite well on the transformers where the throttle could be used between zero and five 5 volts. Then again, the old postwar Lionel Pullmor motors also have some issues at low power settings.

As always, your mileage may vary.

wolverine49