Running two track loops with a postwar 275 watt zw transformer approximately 5' by 12'. When running feeder wires A output goes to track 1 center rail and U to common rail. D ouput goes to track 2 center rail and U to common rail. I know the center rail needs to stay separate but since I am using the same transformer for the 2 tracks do I need home runs for the common or can I connect tracks 1 and 2 commons since that is what the transformer does anyway. And yes I am using 14 guage wire as so many of you have suggested but can you use 4 to 6 inch 16 or 18 guage feeders up to the track. As always thank for your help.
Harold
Xmass is coming... trains will be running.... fa la la la......hope no fires burning....ha ha ha ha ha
Yes you can connect all the commons together. The only requirement is that you post pix!
Not only can you connect the commons between the tracks, you can do so at multiple locations if your tracks come close together and thereby reduce the voltage lost in the return side of the circuit.
Taps of slightly smaller wire for the last few inches are safe. Keep them as short as possible.
If you have a crossover between the two tracks, you need something other than a direct connection to the center rails from the A and D outputs. The transformer's circuit breaker does not protect against the fault current that can result from a train crossing from one track to another powered at a different voltage.
Bob Nelson
Balidas, Thanks for the info when I get some pix I will try to figure out how to get them on here.
Bob, I have read other posts probably from you about crossings so I am not going with that at this point. I am however using your advice (and others) on an incline that will be about 9 feet long and about 6" drop which I know is steep. I am using the bridge rectifiers you suggested back in 2007 I think. I bougt 2 at radio shack and it seemed to work in my test. I'll let you know in a week or so when it is up and running.
Bob,
Can you tell me what I do need to put up to make this work. I have read your warnings and I am confused as to how to protect my zw from them.
I run my ,layout with a pw zw and I have 2 connecting loops. Each handle powers one loop and I have a break in the track connection where they join. Some say put. A circuit breaker in series with the two outputs on the zw? Am I better just running my layout with two smaller transformers?
The block theory makes sense with
No need for two transformers. The pw ZW is good unless you are operating trains and layout accessories on the combined tracks that exceed the transformer's 170-180 watt capacity [about 9-10 amps].
It appears that you are already following Bob's advice by interrupting power, via a gap or insulator pin, between the two throttles in the crossover's center rail which prevents being exposed to the breaker problem he defines when a train is crossing.
The best pw transformer protection IMHO is external: [1]use fuses in holders or thermal breakers for each throttle [power district or block]. [2]Wire a TVS from "A" binding post to a "U" post and another from "D" to a "U" to protect against voltage spikes that can damage Locomotive's fragile wires and circuit board's solder traces.
A gap in the crossover is certainly necessary; but my advice is that a simple gap is not safe.
When a train crosses such a gap between tracks powered by different transformer outputs, the locomotive pickups, and those of any lighted cars with dual pickups connected together within the car, will connect the two transformer outputs together. If the voltages are close and the connection brief, there may be no problem. But if, for example, a train stalls over the gap, damage may occur.
If two transformers are involved and the wiring is appropriately heavy, one of their circuit breakers should trip before any harm is done. But, if the two tracks are powered by different outputs from the same transformer, like a ZW's A and D terminals, the circuit breaker will not trip, and transformer and wiring can be destroyed.
One way to make use of a ZW safe is to add supplementary circuit breakers to the individual outputs, either externally or inside the case. But the best solution is not to expose your layout to this problem in the first place. This can be done by adding a couple of SPDT switches to your wiring. For each track, connect the common of a switch to the center rail, and the other two switch terminals to the A and D terminals of the ZW. Then you can assign each track to either transformer control and run a train safely over the gap by assigning both tracks to the same control, at least for the duration of the crossing over.
There are other benefits: You can divide your layout into as many blocks as you want, even though you have only two transformer controls, at the expense of only one SPDT switch per block. By choosing your block boundaries carefully, you can get two trains to swap tracks, with one waiting for the other. If you use center-off switches, you can also park a train on a dead block and still run two other trains elsewhere on the layout.
You have helped me several occasions with great advice. I am going to do the spot switches as described so I can turn on both tracks to one side of my zw when I transition as well as inserting a number of blocks.
If you are ever around NYC let me know. I owe you a beer.
You're very welcome. I'll keep that beer in mind if I should travel that way.
Here's another little tip: Mount the switches so that the handles go left and right instead of the usual up and down. That way it will be obvious which ZW control each block is switched to.
Hummmmm,
Questions will follow. I want to know how to connect two loops run off of two power supplys without burning something up., E.g. go from one loop to the other loop???
Kev.
Joined 1-21-2011 TCA 13-68614
Kev, From The North Bluff Above Marseilles IL.
You won't burn anything up going between loops, though you should have the transformer settings similar for the transition.
John,
Do you need to install fiber pins in all three rails where you cross from one loop to the other? I will be doing it passing through 027 remote switches.
Tks,
Wire them according to my long post above. Then assign both loops to the same supply while you run the train across the gap.
Will do,
Thanks Bob.
Kev
bob,
I wired as instructed above and it works great by the way. One question I do have though and for you it is a pretty simple one. I wired indicator lights on each side of the switches that would come on when i activated each side of my zw - one problem - they wont come on.....
I followed your instructions above. the switches are mounted laterally...and two lights are stacked on each side (red for left and green for right). I connected one lead from the light into the activated hot lead on each side of the switch and the other lead from the light wired into the common ground on my layout from my zw.
Any idea why this won't work? I want the lights to come on when i fire the switch to each side of my zw.....
As I understand you, there is one light to the left of each switch and another light to the right of the switch. Each light is returned to the transformer common (U) and the other terminal of each light goes to the switch terminal that connects to the center rail of the block.
I would expect that the lights would not light up unless there is voltage on the track, since they are connected effectively between the center and outside track rails. If you turn the voltage up, do you get any light?
For your lights to work all the time, even when the train is stopped, the simplest solution is to use a double-pole switch (DPDT) instead of a single pole (SPDT). Then you can power the lights separately, from an accessory voltage that is always on.
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