Across the transformer outputs (e.g., U to A, U to D, etc.) across the lock-on terminals, across the center and outside rails, these are all electrically equal, are they not? Scatter them around the layout anywhere that is convenient. You don't even have to solder them if you can make a good tight mechanical connection, such as with screw-down transformer output posts. (In other places I generally solder them, and replace them now and then.)
Inside an electronic engine, tender or accessory is also good and has been discussed in this thread.
I come from the area where there used to be Little Tavern mini-burger joints. Their slogan was "Buy 'em by the bag." That's my advice with TVS diodes too. Buy several and hook em up. One might be bad. Hard to tell.
By the way. The various train forums are filled with complaints that "my electronic locomotive (or component) worked fine when I put it into storage last January, but when I tried it this year it was dead." Does anyone know of a case where this seemingly inexplicable event has happened to an item that was protected with an (internal) TVS?
I'm gad someone brought this up. I have soldered feeders every so many feet, do I just solder these TVS where the feeders are from the center rail to the ground rail? Do I have to re-solder my feeders with the TVS or can they be spread out and soldered to the track independently around the loop? Hope that makes sense?
I understand that the bast place is inside each modern engine as stated already. I have mine on the lockOns
For lockOn use You can solder it to the LockOn
Joined 1-21-2011 TCA 13-68614
Kev, From The North Bluff Above Marseilles IL.
There are pics available, but I can't take the time to find one this morning. Basic hook-up is simplicity itself, however. You wire a TVS diode ACROSS the output terminals of your transformer; that is, between Red and Black, or hot and ground, or whatever you choose to call it.
In practice, on a postwar ZW this means you simply hook it up between posts U and A, assuming you are using them as the throttle to power to the track. You can also hook them up across the terminals of a lock-on device, or between the middle rail and an outside rail of your track, etc. If you did this with a piece of ordinary wire, you'd create a short-circuit; but TVS diodes are not ordinary conductors, they are devices. At ordinary track voltages they are "invisible" to the current and only "react" when they detect a voltage spike, which they squelch.
The basic principle is that in toy trains of the Lionel type, you must account for two potential problems, or else bad things could happen:
1. Current that is too high (short circuits)
2. Voltage that is too high. (spikes)
Two totally different problems requiring two different solutions:
The over-currents are dealt with by circuit-breakers or fuses. Voltage spikes are dealt with by TVS diodes.
With pre-and post-war equipment, voltage spikes were no problem. The circuit-breakers in the ZW transformers were very slow acting, typically 11 to 40 seconds according to my principal source.
Modern locomotives and other table-top gear typically contain electronic circuits which are pretty rugged with respect to current but very vulnerable to voltage spikes.
If you are only going to run pre-and post-war equipment on your layout, you don't really need protection against voltage spikes, but with modern electronic equipment you need BOTH.
"Fast-acting" fuses or circuit breakers are a pain-in-the-butt. They react too fast, limiting the current well before theire is any real dangerous problem, but are nowhere near fast enough to "clamp" voltage spikes.
If I cite him correctly, lionelsoni suggests putting a TVS diode as close as possible to the item you want to protect. In the case of modern locomotives this mean inside the case. In a loco, this would mean between the wire from the pick-up rollers and the "ground," generally the chassis. This has the added advantage of protecting your loco if you should run it on a friend's layout, which may not have TVS protection.
TVS diodes are considered rugged, but their one weakness, as I see it, is that they are hard to test. So I use several on my layout (they are so absurdly inexpensive you can buy 'em by the bag) and scatter them around. They do absolutely nothing until needed.
Consider them to be akin to the protective device into which most of us protect our computers and other expensive electronics. The normal 15-amp fuses or circuit breakers in your household breaker-box protect against too much current; but many of us also use "surge protectors" to "clamp" voltage spikes in the AC circuitry. Your trains need similar protection between the transformer outputs and the trains. Note: some modern train electronics devices already incorporate both current and voltage protection, but we are talking here about a post-war ZW which AT BEST only has high-current protection -- and you ought to check (or have checked) the operation of the circuit breaker, AC power wire, etc. The 5-amp fuse or breaker that your dealer mentioned would certainly limit over-currents, but why restrict a ZW to a mere 5-amps when it was designed for 15? Some folks use an external 10-amp fuse or breaker for ultra-safety.
Hope this helps you or someone.
i am not very good with this stuff so can anyone post a picture of where these TVS are connected on the transformer and track, that would help me and my dad.
Here is a link. I have them at almost all of my LockOns
http://www.mouser.com/ProductDetail/Littelfuse/15KE36CA/?qs=sGAEpiMZZMsYiK5PgaDog38p0a8Da%252bhYSQsfo594C0A%3d
External fuses or circuit breakers will protect your transformer and wiring, not your locomotives. To protect electronics-heavy modern locomotives, use a transient-voltage suppressor (TVS) for each ZW output. Connect it between the U and whichever of the A, B, C, or D terminals is powering the track. I recommend the 1.5KE36CA, which you can get from Mouser and other electronics distributers.
The ZW is not protected from connections among the A, B, C, and D terminals. You can use external circuit breakers on the individual outputs to correct this. If you use 5-ampere circuit breakers, you may wire your layout with wire as small as 20 AWG. With 10-ampere breakers, use wire no smaller than 16 AWG. With 15-ampere breakers (which is the rating of the ZW's inadequate internal breaker), 14 AWG. Automatically resetting automotive-type breakers are the most convenient. They allow brief overloads, which are not harmful to the wiring or transformer.
Bob Nelson
Congrats on the zw find. There are things that you definitely need to do, but I believe that you have been totally mis-advised thus far.
I hope "lionelsoni" will address this question. Meanwhile, try searching the archives for this site, looking especially for posts authored by lionelsoni with the keywords TVS, fuse, etc.
In one sentence, no fuse or circuit-
breaker will protect sensitive electronics in modern locomotives or other running gear or table-top items. Fuses/circuit breakers, properly sized, will protect transformers and associated wiring, but NOT electronics. TVS technology, i.e. its application to toy trains is incredibly simple but for reasons beyond my ken seems to be resisted by far too many "experts."
If you are certain that your new ZW has a circuit-breaker that is working (not a given, by any means) you may run postwar and non-electronic stuff but wait until you understand TVS before using it with them.
my dad recently found a ZW 275 transformer for my layout and I was told I need to add a 5 amp fuse or a circuit breaker somewhere to protect modern locomotives, can anyone shed some more light on this? I run both postwar Lionel, modern Lionel and MTH trains.
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