lionel transformers

[Anonymous]

 

Hi

I am about to start setting up my old Lionel layout once again. I have 2 x ZW's and 1 x KW which I would like to use. Providing that the transformers are "phased" properly and grounded in the proper manner, is there any one out there that knows ,(or has tried) the following;

 - can a train engine travel over two sections of track that have been insulated from each other (with fiber pins)  that are powered by 

a) two sides of a ZW ( the same transformer)?   or 

b) two separate ZW'S? 

c) if any , what damage could occur? 

thanks for your input. 

Merv 

[Anonymous]

With the same or different transformer,damage can occur unless the voltages are set exactly the same.. The right way to do it is to set up a transition block. When the whole train is in the block you switch the transformers either with a toggle switch or an automatic relay system.

Dale Hz

[Anonymous]

The damage which can occur is that the voltage will backfeed into the transformer with the lesser potential if the taps are connected in parallel. It would create a hot spot and burn a section of the secondary winding. The transformer breaker may not protect the transformer in this instance because it is not a fault to common. Every time an engine, car with 2 pickup rollers or even a single roller itself bridges the fiber pin, the transformer taps are connected in parallel.

Dale Hz

[Anonymous]

Merv

I got your Email but the system does not allow me to respond. If you can make an outside insulated rail,it is not hard to make an automated system with relays to transfer the transformer power safely. All you need is an insulated center rail as long as the maximum train lenth and one outide insulated rail on each end. As the train passes through the power is switched so the transformers are never connected.. You would need 2 relays per transition and a dedicated tap on one ZW for relay power. Relays cost about $8 each.

Dale Hz

[lionelsoni]

Merv, the automatic system that Dale describes is handy if your trains will repeatedly move between areas powered by different transformer outputs.  But, if you are simply planning on, for example, two loops with a crossover or two to get the trains from one loop to the other occasionally, a traditional toggle-switch setup might work for you.

Just subdivide the layout into as many blocks as you think you'll need by putting gaps in the center rail.  Then use a single-pole-double-throw-center-off (SPDT-CO) switch for each block to connect that block's center rail to one or the other of the transformer outputs, or neither if you just want to park a train in the block.  This way, the toggle switches keep each train connected to the same control all the time.

Plan the block boundaries so that the trains never need to be in the same block while swapping loops.  Notice that you can make as many blocks as you need with only two transformer outputs.  If you want to be able to run more than two trains, there are simple ways to expand the toggle-switch setup.  For example, for each block, a SPDT can select the transformer and a DPDT can select which output from that transformer.

[ADCX Rob]

The damage which can occur is that the voltage will backfeed into the transformer with the lesser potential if the taps are connected in parallel. It would create a hot spot and burn a section of the secondary winding. The transformer breaker may not protect the transformer in this instance because it is not a fault to common. Every time an engine, car with 2 pickup rollers or even a single roller itself bridges the fiber pin, the transformer taps are connected in parallel.

Dale Hz

One way to avoid this trap is to use modern power in phase - CW / MW / RS-1 / PM-1 / TPC300/400 / MRC / Troller.  "Backfeeding" the triacs won't do anything - the one set higher will just continue with it's output to both blocks until the gap is cleared.  No shorts.

Rob 

[nblum]

Shouldn't be a big problem if you follow any of the above advice.  If these transformers haven't been serviced (electrical cord replaced for example) since manufacture in the 1950s it would be worth having them inspected and serviced by an experienced transformer repair-person before use.

[lionelsoni]

Rob, I agree with respect to the CW80.  But do you know the circuit details of the others?  Some of these seem not to be using phase control.  For example, MRC brags that a couple of theirs put out pure sine waves.  (Presumably, the other does not.)  I would hesitate to connect them together without knowing what's inside.  In fact, MRC warns for all their transformers, "...care must be taken that wires do not touch more than one terminal at one time."  I did not investigate the other brands; but would be cautious in generalizing about them.

(The MRC transformers would also seem to be limited in the accessories department if accessories cannot use a return that is common with the track.)

[Anonymous]

I am not familiar with the circuits of the various modern transformers. Since they put out AC I would guess they use paired triacs to regulate both halves of the sinewaves. I am not totally sure if the triacs like voltage on the load side,just dont know. Even if the transformers allow cross connecting different voltages it is still not a good idea to run a lot of amperage a whole train would pull through 22 gauge or less wire which connects the pickup rollers. These wires were only intended to carry lightbulb current. If powered too long the wires could melt down. A fellow on another forum suggest putting poly fuses (an automatic resetting fuse) between the pickup rollers. I do this now on all my dual rollered cars to protect the wires during a derailment.

Dale Hz

[lionelsoni]

I suspect that those that advertise "pure" sine waves do not use triacs, which do not turn off once turned on, until the end of the half-cycle.  That's good for phase-control circuits but not much else.  I would expect a "pure" generator to use some sort of transistors (FETs perhaps) switching at a high rate to chop DC or the transformer's sine wave, followed by a low-pass filter to get the desired purity.  If a totem pole is used, it would have the same problem as simple transformer taps when outputs are connected together.

[ADCX Rob]

Rob, I agree with respect to the CW80.  But do you know the circuit details of the others?  Some of these seem not to be using phase control.  For example, MRC brags that a couple of theirs put out pure sine waves.  (Presumably, the other does not.)  I would hesitate to connect them together without knowing what's inside.  In fact, MRC warns for all their transformers, "...care must be taken that wires do not touch more than one terminal at one time."  I did not investigate the other brands; but would be cautious in generalizing about them.

(The MRC transformers would also seem to be limited in the accessories department if accessories cannot use a return that is common with the track.)

I should have whittled this down a little more.  The MRC units(Tech II & AH) are triac controlled, but the Pure Power series probably not... I have not disassembled them yet.

Rob 

[martinden]

Unless I am very mistaken, the MRC "PurePower" transformers don't have any triacs or anything else -- they are variable transformers, with contact arms (with rollers, I think) that move across the secondary winding.

[lionelsoni]

I take that as good news.  It's such a simple concept that I wonder that anyone thought they could improve on it.

[msacco]

With all due respect to the great electrical knowledge here I continue to do "what you're not supposed to do". That is , running my locos up a grade set at a higher voltage coming from another channel on my ZW.

   Now, my new zw is phase controlled and delivers chopped sine wave I believe, and I've been runnng  a year or so now and have experienced no problems with traditional motive power and electronic controlled motive power.

Mike S.

[ADCX Rob]

With all due respect to the great electrical knowledge here I continue to do "what you're not supposed to do". That is , running my locos up a grade set at a higher voltage comming from another channel on my ZW.

   Now, my new zw is phase controlled and delivers chopped sine wave I believe, and I've been runnng  a year or so now and have experienced no problems traditional motive power and electronic controlled motive power.

Mike S.

I've been doing the same thing for over 40 years w/ ZW's, KW's, SW's, TW's, 1033's, R's, RW's, & more with nary a failure or problem.  You should have even less of an issue with the new ZW controllers.

Rob 

[Anonymous]

Heres a little experiment you can do at home if you have a PW ZW. Set the AU votage at 6 volts and the DU voltage at 18 volts. Insert a voltage meter across the A and D terminals,it will measure about 12 VAC. Now connect a 22 gauge wire across the A and D terminals this will simulate a dual pickup rollered car bridging 2 insulated blocks It is not far fetched a train could stall or derail in this position. Now watch the wire burn up and see how long the transformer breaker takes to trip,it wont. The same thing can happen inside a caboose or passenger car. Not saying it will happen I am saying it can happen.

Many times people do unorthodox things with electricity and get away with it such as bury extension cords under carpets,plug in 15 amp heaters into 16 gauge extension cords ect but that does not make it right as there are always people who will have problems with tragic results.

Dale Hz

[lionelsoni]

Amen, Dale.

I have mentioned before that I have a couple of Z transformers with burned sections in the middle of their windings.  I can't imagine how that could have happened other than that two outputs set to different voltages were connected together, probably with heavier than 22 AWG wire.

Mike, phase control and chopping are two different things.

[Anonymous]

Bob

I read that post,that is what piqued my curiosity to do the experiment. When you connect the terminals A and D the wire burns up quickly and I suspect the burning does not stop at the terminal post, it goes through the winding to where the potentials are equal. That would explain the burn spots you observed in the secondary winding. I always learn something reading your posts,makes me think which is not that easy for me, thankyou. 

Dale Hz 

[msacco]

Bob, Dale,

Okay, so what do you think is happening in my new zw. Am i correct in saying that the controller and the power bricks do not have windings? If they don't what do you think is going on electrically here?

Mike S.

 

 

[lionelsoni]

Mike, I'm afraid I don't know a power brick from an MP3 and am not quite interested enough in either to go to the trouble to find out.  But, if someone were to send me schematics of a modern "ZW", I could venture a guess how it works.  You could answer one question, however, by doing Dale's experiment with it, to see whether it burns up the wire, if not the controller or power brick or whatever.

[Anonymous]

Bob, Dale,

Okay, so what do you think is happening in my new zw. Am i correct in saying that the controller and the power bricks do not have windings? If they don't what do you think is going on electrically here?

Mike S.

Mike
I actually have 2 modern ZWs with 8 bricks. They are good transformers with excellent breakers but I dont know how they work. Without a schematic I could not speculate.Again even if the transformer is not at issue the possibilty of powering a train through a 22 gauge pickup wire is real. A modern ZW would not see this as a short because it is not a short,it is  circuit with a lot of amps is going through a small wire..The wire can melt.  All I am saying is this is not good electrical practice.The original post pertains to a PW ZW not a modern ZW. I am not an expert nor am I trying to be argumentative or a wise guy  here. There was a post a while back on another forum with pictures of caboose wires and shells melted down during derailments. Electronics is a hobby of mine but I take safety seriously. If some engineer writes of a possible problem I investigate it. Bob knows a lot more about the theory of this stuff than I do. If he sees burnt windings I dont think he makes up stories. I dont want something on fire on my layout if I can help it.I am more of a repair technician. You may want to ask the people over at Lionel. I dont trust them completly either.You know some of the early Lionel bricks were out of phase with eachother?

Dale Hz 

 

 

[bfskinner]

There schematic drawings of the circuit as well as "exploded" views of the modern Lionel ZW Controller on Lionel's website under Customer Service.

None of the power bricks (Powerhouse) that I could find, alas.

[Anonymous]

 

Feb 28 2007

Thanks for all of the above input - helps out a lot!

Merv 

 

 

[lionelsoni]

Thanks, BF.  I found it; but indeed it is the wrong end of the machine and not very informative, just a computer with a bunch of pots and switches connected to it.