They generally keep the two separate on the NEC

But I bet you can find a prototype somewhere.

I have an Acela Express too,

I have an Acela Express too, as well as a couple other Amtrak electrics. I have not yet figured what I will do with them, but they are kind of neat. The problem I could see is the reach of the pantographs, out of the box. My AEM-7 has a high enough reach that the catenary could clear a double stack, but only barely. The catenary could not be working, because at that height, the pantograph would not have enough pressure against it to have a reliable electrical connection. My HHP-8, on the other hand, has a reach that is exactly the height of a double stack, so it would need a new or modified pantograph.

Another consideration is container height. There are standard height containers and "hi cube" ones. You would want the catenary high enough to clear two high cube containers (which are about 6 inches taller), otherwise there would have to be restrictions on loading and container sizes. And really, if your wire is that close to the top of the containers, in the 1:1 world, you'd be tempting the wire to arc to the containers and try to ground. There are a lot of volts in those wires, especially on the NEC!

Sommerfeldt

Check them out for good, modern cantenary.

Here is a photo

This is the look I would like to achieve. Apparently this is in the Philadelphia area and host at least SEPTA electrics. It would seem like AMTK would or could also use these wires. So, are the clearances higher here than normal? This photo came from RailPictures.net and is taken from the Septa Norristown Transportation Center

Also, what might one do to raise the height of the pantographs? I agree, I would worry about good contact between the pantograph and cantenary. I am truly surprised that the Atlas does not reach as high as the Bachmann, but maybe, the Atlas has a truly scale height whereas the Bachmann is taller than prototype. My Acela probably could hit the wire with just enough clearance. That brings up the whole issue of arcing through a container to ground was something that I had not even considered in real life.

If I am going to string it, I am going to power it and use the Cant. to deliver half the circuit which brings up a whole other issue.... If DCC is AC, does it matter which side is attached to the cantenary and which one is attached to the rail and which one. If it gets complex and goes through a reverser, how is that handled? Where is the Professor when we need him?

Catenary, trolley poles, and track polarity

I did a bit of searching on this when making preliminary plans for my layout.

If the track is ONLY capable of handling electrics powered by the overhead, reverse loops are no longer a problem, since both rails can be the same polarity--something that's handy with traction layouts.

If you also want to run steam and diesel, then you have the usual issues, and need both rails powered for a complete circuit, and the catenary will need to match one of them.

In the old pre DCC days, the overhead would be the common rail, with each rail individually powered, allowing true independently controlled cars on one circuit.

Considering the hassle

of getting DCC to work with good solid rails, I suspect getting a good signal through fine wire and a bouncy pantograph will be tricky.

If you want to mix catenary power locos with standard DCC models, you will have to build the track to DCC spec and run your catenary locos off one rail and the wire as Rover mentioned. You will also have to put auto-reversers in each loco.

I will watch your adventures with interest.

pqe

Explain the auto reversers, please

Now you have piqued my interest...

DCC has a Rail A and a Rail B. If Rail A is the "hot" couldn't Rail A be wired to both an actual rail and the overhead wire?  Rail B could then complete the circuit. This way, a "diesel" or "steam" engine could run as though there was no overhead wire.  Since the "electric" loco would pick up off of Rail B and the overhead wire (Rail A) I guess it would work as long as the correct wheel is picking up from the correct rail... Right?

My wire will probably be un-prototypically thick just to reduce any problems. C'mon, someone must have already experimented with this stuff....

Uh oh.... Time to wire up a test track, I guess.... 

DCC for Acela

Does anyone know if the 8 pin plug on the Acela board is standard DCC wiring? My assumption is yes, but we all know these manufacturers do silly things. 

Any overhead wire engine might be a good candidate for one of the long duration keep alive units?

How about a decoder that would recognize a B rail signal from either wheel, just in case it gets turned around accidentally?

I know Acela has a regular horn and bell, but what other sounds might I want in a sound unit?  I imagine Acela or a E60, AEM7 or an HHP8 would all run fairly quiet but I wouldn't know... We only have the South Shore here in Indiana.

Hmmm, maybe I should split this thread and move some of the DCC stuff over to the Electical/DCC forum ???

couldn't Rail A be wired to both an actual rail and the overhead

 As long as the pantograph or trolley pole is riding the wire no one is going to know if it is picking up power or not. I've seen models that can run off track or overhead but I don't know how they do it. Since DCC could be the same for both electric and diesel powered trains it seems a lot better to just set up all the units for rail power and use the overhead for looks only, that would save a lot of duplication of wiring and simplify the system....DaveB

Turning Electric Engines

The biggest disadvantage I see with live overhead, above track that diesel or steam engines can use, is that your electric locomotives could not be turned around without some fancy electronics. Because the diesel and steam engines require the rails to be of opposite polarity, there can only be one return rail for the electric engines, which take their juice from the catenary.

Example: (I think I can explain it easier this way.) The track has two polarities, we'll call them Rail A and Rail B. For this example, we will also say that the catenary shares polarity with Rail A. On a diesel or steam locomotive, they can be turned around without any consequences, because the A and B just swap sides, the decoder recognizes this, and it acts accordingly. If you turn an electric engine however, the pantograph will still contact Rail A, but the wheels that normally contact Rail B will also contact Rail A, and the decoder will be getting the same polarity power from both sides. If the wheels opposite the normal Rail B side (these would be the Rail A wheels on a diesel or steamer) are insulated from the rest of the electrical system, all you'll get is an unresponsive locomotive. If, however, the normal Rail A wheels are energized when the pantograph is energized, then they would short the system with the locomotive reversed, because the pantograph would try to energize them as Rail A (which they normally would be) and the rail would be trying to energize them as Rail B. Am I making any sense?

Basically, what it all boils down to is that you would have to have a way of identifying which way all your electric locomotives have to face, and then never turn them. On a fixed trainset, like an Acela, that would be pretty easy to manage. On a conventional train, where the locomotive is at one end, you would have to be sure you did not wye the train with the electric locomotive attached. Basically, you would have to either run around the train, or wye the train with a diesel (or steam) locomotive and recouple the electric locomotive afterwards. You might want some way of identifying which way the electric locomotives have to face, but that could be as simple as orienting them so the F stencil faces a specific direction.

Exactly

Thanks, James

Yep, that was a good explanation and something that had crossed my mind...  An electric that gets turned would effectively become unresponsive.

Does anyone know if there would be some kind of decoder that could overcome this problem?  It would have to be smart to know which rail is now Rail B... I do not think anything like that exists.

I guess the idea to just run them with the overhead non energized would work, but I just don't think it is as cool. I dunno... The Acela pantographs probably would stay "locked" for just so many times. Continually changing it for the proper direction of travel might not be a good idea.

If all I ran was overhead wire engines, how would I set up the DCC to handle engines that are turned around? It does not seem to make sense at all, but I am sure the European mfg's. have probably crossed this bridge.

Thanks PQE

Okay, I need a tiny auto reverser circuit then...

Let me know when it is ready...

Like I said just a minute ago, I can not believe the European DCC market has not solved this. With all the things that tiny decoders do these days, it seems like there would be one that could detect which rail on the ground is the correct one to complete the circuit.

Of course, electrics utilizing an overhead would have to be wired a little differently but it does not seem impossible. Maybe my dream is fading?  Maybe I should forget using real cantenary?

Kirk:  I have modeled

 Kirk:  I have modeled electric RRs since the 60s with catenary. As much as I love catenary, which I have on my NH layout, photos of which are on this forum, energizing it gains you nothing! You cannot tell whether or not the wire is energized unless you drop the pan. My current layout which is quite complex would be a nightmare electrically if I energized the wire. The total illusuion is created by watching the pans on the wire. Rick

"Maybe I should forget using real cantenary?"

  No, you can build it and insulate it then decide later if you want to power it or just run it as a non powered system. It will be the same amount of work to construct it either way and it will look the same when done. By the time you are finished with the overhead wire construction there will be more decoder advances and choices. My problem with overhead wire was not how to power it but was how to work around and under it, it creates a maze to reach thru for all the tasks we don't normally  think about when building and running trains. But despite that I'd certainly consider modeling another electric line if I lived where they ran and had a stronger connection to them.As for running just electric locos the way to do that is make the overhead rail A and both rails rail B (or vice -versa) that way the loco don't care which way it is facing.Adding diesels into the mix creates the problem. I suppose you could buy battery powered diesels and insulate their wheels to run with your over head powered stuff. ......DaveB

Catenary for control

The current interest in Radio control systems might result in hybrid DCC decoders- these would be connected to a source of DCC (track or radio receiver) and a source of power (track or battery). Then you could run the DCC commands through the wire and get power from the track. Your non-wire locos would be RC.

Such a product would be in Tsunami etc's interest because they could concentrate on sounds and engine dynamics while other companies deal with the FCC.

Of course, you can't just transmit DCC over the air, the commands have to be re-encoded into something that meets transmission requirements and decoded at the receiver. (This sort of thing is common in radio communications.) That would be to the advantage of the RC vendors, because it would become easy to retrofit their systems into classic locos. All that has to happen is a bit of cooperation between the various manufacturers.

Any day now, right?

pqe

Kirkifer, If you ONLY ran

Kirkifer,

If you ONLY ran overhead engines, then there's no problem, though some equipment modification is needed.  You have both track rails the same polarity, and the overhead, the opposite.  But, you have forever (well, until a MASSIVE rewiring project) eliminated any possibility of running anything else--like the self-powered railcars that many lines use for work when the power is out.

Remember, there has to be some place under the wire that interchanges with non-electric power, so you need top be able to make something run there.

Just a thought on the Acela

I don't think you will be turning it around - the real trains are fixed with a power car (engine) at each end and the consist is fixed - nothing is ever removed or added.  The individual cars have gyroscope control and hydraulic frames that keep the cars level as the train encounters high speed banked curves.  It's terrifically expensive and probably won't be around when Amtrak replaces these trains.  "Extreme Trains" did an entire show on the Acela, including some cool footage through the North River Tunnel leading into Penn Station New York.  The fixed consist allows quick turn around times for these trains, since the engineer simply moves to the opposite power car for the reverse run.

-bill

Reverse loops

I've spent waaay too much time trying to figure out how to do something clever with overhead wire and two rails to control multiple trains at once.  The problem with using one of the rails as a return path is that turning the equipment around (on a turntable, wye, or loop, for example) means that it's now connected to the wrong rail.

In the end, my conclusion is that there's no real justification for using the overhead or third rail, unless that's absolutely all you'll ever run.  The lack or problems with reverse loops is nice, but the additional hassle and lack of ability to run conventional equipment makes it hard to justify.  I'd strongly suggest making it cosmetic only.

You could make a special effect

Actually

(if we are talking DCC) there will be no problems with loco direction whatsoever no matter which rail feed you divert into the catenary.

If you do have reverse loops, all you have to do is to divide your catenary into the same sections as the rails and feed the catenary from the corresponding rail for each section. I.E. if you'd feed the catenary form rail A, than you would feed it from rail A on each section.

I see other problem with powering the catenary: if you intend to also run steam or Diesel, there is no point in powering the catenary: you still have to wire/power the rails as you would do normally for DCC.

As for the Europeans, they do it already: companies like Viessmann have the full range of products. A quick search turned up the following: http://www.ontracks.co.uk/index.php?page=fromLibrary&guide=110;maybe it will help you.

I'm not sure it this applies to your situation, but I have also found this: http://pennsyrr.com/kc/model/downloads/catenary.pdf

to power the wire or not?

I have been pondering this question myself.  It seems to me that if you use a DC power supply, you can use diodes to ensure that power flows down from the wire and out the correct wheel, no matter which way you turn the locomotive.  By having diodes only allowing power to flow toward the rails at each wheel on your electrics, they will not short out the two rails, allowing conventionally powered locomotives to be wired normally.  I believe DCC is technically a DC current, since it cycles between zero and positive square wave, so the diodes should not interfere with it.  I've never tried it, but I see no reason why it shouldn't work; perhaps someone more DCC-savy can correct me.

All that being said, I don't think I would set up my electrics to run off the wire, because they would not be able to operate with the pans down.  Some of the new European models have remote functioning pantographs, which can raise and lower using DCC functions, and that would not work if they depended on the wire for power.  There are also prototypical examples of electrics running short distances with both pans lowered, and that would also not work unless they ran on track power.  Even simulating a shop switcher moving a "dead" electric around the shop would only work if it was running on track power.  Just some things to think about.

Square wave AC

DCC is an AC current according to Allan Gartner's web site. It is rectified to DC by the decoder.

His scopeshot example of a NCE PowerHouse Pro.

1. Track signal voltage right at booster terminals. Proper amplitude, 28.8Vpp = 14.4 DCC track volts. No ringing. Very abrupt transitions, 240 nano-Seconds rise time, 177 n-Sec fall time. This is a "good, clean" DCC signal.

thanks

OK, I stand corrected.  I had initially thought it would work with some radio concept like Ring Engineering, and I think that still holds true.  Nevertheless, I stick with my own position that it's better not to depend on the overhead for power.