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Transformers in series?

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Transformers in series?
Posted by lionelsoni on Thursday, November 19, 2009 8:02 PM

I was brought up short by a statement in Bob Keller's article, "Choose the right transformer", in the January CTT.  He says, "While the postwar ZW may win in the studly looks department, a string of postwar Lionel no.1033s hooked up in series may get the job done just as well."  The 1033 doesn't put out a lot of voltage, but just two of them could get you up to 32 volts, if that's the point.  I think that's as much of a string as I would find useful.  He may have meant to say "parallel" instead of "series"; but that's not a good idea either:  The slightest difference among voltage settings and the transformers will be pumping current from one to another rather than to the trains.

It's also unfortunate that Bob didn't explain the distinctions among transformer power, voltage, and current.  For example, if 16 volts is not enough for a particular locomotive, there is no point in replacing a 90-watt Lionel 1033 with a 300-watt American Flyer 30B--the train won't go any faster.  There's more to it than just power.  The comment, "...long runs of track...require a more powerful transformer", reinforces the fallacy that power loss, not voltage drop, is the enemy of a large layout and that a bigger transformer per se will solve the problem.

While I'm at it I might as well note that John Rusterholz's article, "Wire a trackside signal to a Lionel switch motor", applies only to 022 turnouts and others that shut off the switch-machine coil after throwing the points.  It won't work with Lionel O27 turnouts like the 1121, 1122, or 5121, for example.

And finally, I came across a couple of instances, in different articles, of the word "buss" incorrectly used instead of "bus".  As anyone can see by Googling "buss definition", "buss" means "kiss", and nothing else.  I think this common spelling error might have originated with "Bussman" brand fuses; but it is probably encouraged by modern spell-checkers, which don't have the sense to know that the author or editor wasn't writing about osculation.

Bob Nelson

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Posted by A&Y Ry on Thursday, November 19, 2009 9:24 PM

Bob, the term "buss" was used in U.S. Navy Class A ELectrical School texts [at least in the late 1940s] in describing the heavy A,B &C switchboard bars in the Ship's Service 440 power system . You have made the point about the spelling previously and your point is well taken. But I'm sure you are aware that field useage varies substantially even in the pristine world of EEsCool, even if less so among old SparktriciansDunce and novice model raILroadersSmile.

Is WEBSTER'S Greyhound ["bus"]3 phase or singleWink?

 

 

 

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Posted by ADCX Rob on Thursday, November 19, 2009 11:34 PM

 I once saw a Lionel instruction manual for a 1033 or 1044(maybe even a 4090) that showed how to connect two of them in series.  I think it was to show how to get more voltage to run Standard Gauge trains with postwar & newer transformers.  If I recall, the 2nd transformer was used for it's 5 volt fixed taps only in the circuit diagram.

Rob

Rob

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Posted by lionelsoni on Friday, November 20, 2009 7:26 AM

I searched for "buss" and "bus" in NAVPERS books.  The only instances I found on the Internet were two in 10548, Electricians Mate 3:  "..on generator switchboard bus bars."  They may have spelled it "buss" somewhere; but I couldn't find it.  There's a lot of misspelling and bad usage around; but I would hope that a publication like CTT would aspire to getting it right.

Although the Navy books were my introduction to electronics, after a childhood of messing with toy-train electricity, I have never forgiven them for deliberately trying to reverse the direction of electrical current.  They produced generations of technicians who don't speak the same language as the engineers that they work with.

By the way, notice that the Greyhound type of bus is the same word as the electrical bus.  They are both from the Latin word omnibus, the dative plural of omnis, meaning "for all".  The one-s "bus" is completely unrelated to the two-s "buss".

Rob, that's certainly reasonable.  Sixteen volts is barely enough to get a 773 to move.  Two transformers in series are literally a string; but that's not the word I would use unless I meant a greater number.  How it fits in with the bigger-is-better message of Bob's article, I don't know.

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Posted by A&Y Ry on Friday, November 20, 2009 8:03 AM

I apologize--I did  intend to make fun but not get you all crossways over such a nitppicking issue. Anyway we lesser types did manage to keep the lights on and guns firing during most naval battles. 

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Posted by lionelsoni on Friday, November 20, 2009 8:17 AM

Not crossways at all.  There's nothing to apologize about.  I didn't think there was any offense intended all around.

Bob Nelson

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Posted by cnw1995 on Friday, November 20, 2009 8:22 AM
I've learned more about electricity from your posts over the years than unfortunately anything I tried to learn in class. Thanks Bob!

Doug Murphy 'We few, we happy few, we band of brothers...' Henry V.

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Posted by phillyreading on Friday, November 20, 2009 10:00 AM

I agree with Bob Nelson about not putting transformers in series, to me it is plain dangerous! There are many reasons not to do this but the most important reason is high end voltage.

With all the transformers being made today there should be one made to fit your voltage needs. Current makers of transformers for model trains include; Lionel, MTH, Bachmann, Atlas, MRC, LGB and probally a few others.

Lee F.

Interested in southest Pennsylvania railroads; Reading & Northern, Reading Company, Reading Lines, Philadelphia & Reading.
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Posted by lionelsoni on Wednesday, January 27, 2010 7:19 PM

I happened to glance at Bob Keller's article again and got so curious about his reference to, "Big power for a small price:  Using several small transformers in series", that I paid CTT $8.90 to send me a copy of the October, 1990, issue.

The article is by Ray Plummer and is actually titled, "Big power for a small price--Use a number of smaller transformers to operate your layout".  All Plummer was saying was to buy a pile of small transformers and hook them individually to blocks on the layout.  There's nothing about wiring them in series either in the title nor in the article.  That's a relief; but how did series transformer wiring got into Bob's recommendations and even into the transmogrified article title?

Now don't get the idea that I like Plummer's recommendation.  I still disapprove of running trains from block to block powered by different transformers, for reasons of fire safety that I have belabored endlessly here on the forum.  But at least his proposal wasn't as bizarre as Bob's "string of...1033s hooked up in series [to] get the job done...".

Bob Nelson

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Posted by ADCX Rob on Wednesday, January 27, 2010 8:50 PM

ADCX Rob
 I once saw a Lionel instruction manual for a 1033 or 1044(maybe even a 4090) that showed how to connect two of them in series.  I think it was to show how to get more voltage to run Standard Gauge trains with postwar & newer transformers.  If I recall, the 2nd transformer was used for it's 5 volt fixed taps only in the circuit diagram.

 

I found the manual I referenced above.  It's for the 783 Hudson, and it shows two 4090's wired in series with the 2nd transformer used for it's 5 volt fixed winding to boost the output to 21 volts total.

The online manual at Lionel.com has been revised with this section deleted.

Rob

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Posted by Banks on Wednesday, January 27, 2010 9:01 PM

 The guys at CTT can't seem to understand that more track feeders will accomplish more to overcome the voltage drop of track joints than a bigger transformer. A bigger transformer will only make the train go faster near the lockon.

Banks, Proud member of the OTTS  TCA 12-67310

  

   

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Posted by dogdoc on Wednesday, January 27, 2010 9:14 PM

Why not put them in series if you need a little more voltage ? I f you are watching things while running your trains , whats the big deal? I understand not needing 32 volts from 2 1033s but how about the method the old instruction manual reports? 

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Posted by Train-O on Wednesday, January 27, 2010 10:07 PM

Bob,

Your valuable information is well taken and appreciated, especially that you intend for us to be safe and keep, not only our model trains intact, but our lives and homes.

Thank You,

Ralph 

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Posted by servoguy on Wednesday, January 27, 2010 10:44 PM

 I think I would advise against putting transformers in series unless you are very careful.  Doing this would make it very easy to exceed the maximum current of the transformers.  Some of the smaller transformers don't have circuit breakers, and they could overheat and perhaps catch fire. 

 Years ago, when I was about 12 (1953), I remember using two Lionel Scout transformers in parallel to run a train.  I was careful to phase the transformers properly, and to keep the controls at about the same setting.  It worked OK.  Why do you get more power out of two transformers in parallel than a single transformer, you may ask.  It is because the transformer has a non-zero output resistance.  For the smaller transformers, it can be several ohms.  For a KW and Type V, it is about an ohm.  For a 1034 it is about 1.5 ohms.  This is why the voltage of the transformer drops when you put a load on it.  

When you put two transformers in parallel, this output resistance keeps the currents from getting very large. For example, if you had the two outputs of a KW powering two blocks, and a train ran from one block to the next, and the two outputs were different by two volts, the current draw due to shorting the two outputs together would only be about 1 amp and would not harm the transformers even if the short continued for some time.  With this said, let me say that Bob Nelson's method of using switches to switch blocks from one transformer output to another so that a train is powered by a single transformer output as it goes between blocks is the best way to do things, and carries the least risk of a problem.

Lionel designs their transformers to have a fairly high output resistance because they are variacs.  When the roller rolls across the windings, it shorts two windings together.  The roller resistance and the transformer design limits the current in the shorted winding.  This reduces the efficiency of the transformer.

Bruce Baker

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Posted by lionelsoni on Wednesday, January 27, 2010 11:00 PM

I don't have a problem with using one transformer to boost another by a few volts, by someone who knows what he is doing.  But "a string of...1033s" is over the top!

I agree that the fault current is less between smaller transformers; but you still can't let the voltage difference get out of hand.  And, in any case, there will be an inductive voltage kick each time the connection is broken, which can be bad news for some of the modern electronic locomotives.

All that aside, how did the article's title change and its content get misrepresented twenty years later?

Bob Nelson

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Posted by LocoPops on Thursday, January 28, 2010 7:26 AM

lionelsoni

 if 16 volts is not enough for a particular locomotive, there is no point in replacing a 90-watt Lionel 1033 with a 300-watt American Flyer 30B--the train won't go any faster.

Bob, 

I'm gettin' confused.  What would the 300-watts buy you then?
 

Pops
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Posted by lionelsoni on Thursday, January 28, 2010 8:36 AM

Suppose you have 20-ampere 120-volt branch circuits in your house, which is very possibly what you do have.  You plug a 60-watt lamp into one of those circuits and it lights up, drawing 1/2 ampere of current.  Now suppose you open up your panelboard and connect the lamp instead to the very large wires coming out of your 200-ampere main circuit breaker.  It lights up just the same and draws the same 1/2 ampere that it did on the much smaller branch circuit.  The only difference is that the first time, it draws 1/40 of the current that the circuit can supply, the second time it draws 1/400.  But it doesn't get any brighter just because the circuit can supply 10 times as much current.  How much it draws depends only on the voltage supplied to it, 120 volts, up to the point where the circuit breaker trips.

The same thing happens with the 1033 and the 30B.  The 1033 supplies 16 volts up to 5 amperes and the 30B supplies 15 volts, up to perhaps 15 or 20 amperes.  As long as the train draws less than 5 amperes, it will behave the same with (almost) the same voltage.  It doesn't know how much more current the 30B could supply.

The only thing the 30B would buy you is the ability to run more or bigger trains, but still at the fairly low voltage of 15 volts.  If all you have is a train or trains that don't run fast enough at 16 volts but don't draw more than the 5 amperes that the 1033 can supply at 16 volts, they will run no faster with the 5 amperes that the 30B will also supply, at 15 volts, perhaps a little slower because of that 1-volt difference.

Bob Nelson

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Posted by LocoPops on Thursday, January 28, 2010 8:59 AM

 Bob,

Whoa, I think I actually understand it now.  Thank you.

So then the "more or bigger trains" would draw more amperes (and watts) and would therefore benefit from the 30B.  Is that correct?


Pops
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Posted by richhotrain on Thursday, January 28, 2010 11:23 AM

lionelsoni

Suppose you have 20-ampere 120-volt branch circuits in your house, which is very possibly what you do have.  You plug a 60-watt lamp into one of those circuits and it lights up, drawing 1/2 ampere of current.  Now suppose you open up your panelboard and connect the lamp instead to the very large wires coming out of your 200-ampere main circuit breaker. 

Bob,

I immediately got confused, but then I realized that you had a typo when you started out by saying 20-ampere when you intended to say 200-ampere.  Just thought I would mention that in case anyone was confused.  In any event, I was trying to imagine someone owning a house with 20 amp service in this day and age.  Big Smile

Rich

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Posted by richhotrain on Thursday, January 28, 2010 11:34 AM

lionelsoni

It's also unfortunate that Bob didn't explain the distinctions among transformer power, voltage, and current. 

Bob,

Let me ask a basic question about electricity as it relates to transformers.

I have a multimeter that that I periodically use for testing on my layout.  Recently, I had reason to check the amount of power reaching the track from my old American Flyer 8B transformer.

My multimeter has instructions for measuring, among other things, both voltage and current.  My assumption was that I wanted to check for voltage, and I did so getting a reading around 16 to 17 volts on the rails, so I assumed that everything was working properly with the transformer.

That being the case, why would I measure current?  Or, put another way, what is the distinction between voltage and current?

Rich

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Posted by LocoPops on Thursday, January 28, 2010 11:57 AM

richhotrain
Bob,

I immediately got confused, but then I realized that you had a typo when you started out by saying 20-ampere when you intended to say 200-ampere.  Just thought I would mention that in case anyone was confused.  In any event, I was trying to imagine someone owning a house with 20 amp service in this day and age.  Big Smile

Rich

 

Rich,

That wouldn't be a typo. The "20-ampere" referred to individual "branch circuits".  Not the main circuit breaker, which Bob gives as "200-ampere" in his example.


Pops
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Posted by richhotrain on Thursday, January 28, 2010 11:59 AM

LocoPops

richhotrain
Bob,

I immediately got confused, but then I realized that you had a typo when you started out by saying 20-ampere when you intended to say 200-ampere.  Just thought I would mention that in case anyone was confused.  In any event, I was trying to imagine someone owning a house with 20 amp service in this day and age.  Big Smile

Rich

 

Rich,

That wouldn't be a typo. The "20-ampere" referred to individual "branch circuits".  Not the main circuit breaker, which Bob gives as "200-ampere" in his example.


Oops, sorry, I misread that the first time.

 

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Posted by lionelsoni on Thursday, January 28, 2010 4:35 PM

That's right--I did mean a 20-ampere branch circuit.  Fifteen or 20 amperes (only 15 in Canada) is the rating of the circuits that you plug an ordinary parallel-blade (1-15P or 5-15P) plug into.  You have many of these circuits in your house, all fed from a much heavier circuit, like the 200-ampere one I used as an example.

Voltage is a sort of electrical force.  In fact, it is often called "electromotive force", "emf", or "potential".  "Voltage" is a little less of a mouthful then these more formal terms.  It is a little like pressure in plumbing, which you might measure in pounds per square inch or psi.

Current is the flow of charge, usually electrons, and is measured in amperes.  Some people say "amperage" instead of current; but that is a little like calling a tender a "coal car".  It is a little like the flow of water in plumbing, which you might measure in gallons per minute.

Our transformers are close to being constant-voltage sources.  When you connect a load, like a locomotive or a lamp, to the transformer, a current flows through the load.  How much current flows depends on the voltage that the transformer is putting out and just what the load is.  If the load is a resistor, the current is proportional to the voltage; but many loads are not resistors.

The power that the load consumes is equal to the voltage multiplied by the current.  It is usually measured in watts in electrical matters; but it is the same kind of power that is measured in horsepower, btus per hour, calories, and tons of refrigeration; and you can convert it into those units if you need to.

Bob Nelson

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Posted by richhotrain on Thursday, January 28, 2010 4:53 PM

Bob,

Thanks for that explanation of voltage, current and power.

That helps me a lot in making those distinctions.

Rich

Alton Junction

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