Catenary

[ebay mike]

Couldn't find a specific section relating to 'overhead' matters and as I've got more than one question I thought I'd put them all in one place. Over the years I've accumulated quite a number of locos, trains and trams with pantographs, bow collectors or trolley poles. To date I've relied on the 'imagine it's there' principle in respect of the overhead wires. Not long ago there was a rather animated discussion in the coffee lounge about the lack of realism when running locos with pans down (or up with no corresponding infrastructure). This got me thinking as I have accumulated a significant stock of related items - enough to do a complete installation on my layout.
Here goes:

1. Who runs stuff with the pantos up and actually in contact with the wires?
2. Who relies on power via the overhead? I saw recently it can be problematic with DCC.
3. Are there any associated problems with wear on either of the 'bits'?
4. What about (in particular PIKO) stock that have current collectors made of plastic? Do you replace them with metal ones or adopt a method similar to Nodrog who uses fishing twine to limit vertical movement which would prevent actual contact?
5. Who uses trolley poles (with wheels) on the LGB brass wires and are they troublesome?
6. Some of my locos are DCC (Kroks, Taurus, LCEs etc.) but I have a number of analogue LCE sets and trams. Is it feasible to have analogue running at the same time as DCC using one rail as the feed and the overhead as return if the chipped engines are track powered only?

No doubt there are other things I need answers to, but this will do for now.

Just as a matter of interest I have several masts with bases. I recently bought some solar powered lights from Poundland which came with two part brackets I did not need for the installation I required. With a small amount of packing/adaptation they look as if they will fill the role at a pound a pop rather than the £5 plus for LGB ones. No promises or guarantees about suitability, but I'm off to the shops to stock up on a few before they all go. For the uninformed the genuine LGB item is the light grey one.

 

[Madman]

At one time I ran live catenary in the garden. I would still have it but my garden railway is at ground level so gardening chores became a bit problematic when anyone other than I did any gardening. I am also building an "O" gauge layout. At present, I have live catenary on my experimental "O" gauge layout. I hope to build a permanent layout in the garage attic if and when D2 gets her stuff out.....I'm not holding my breath.

 

[ebay mike]

At one time I ran live catenary in the garden. I would still have it but my garden railway is at ground level so gardening chores became a bit problematic when anyone other than I did any gardening. I am also building an "O" gauge layout. At present, I have live catenary on my experimental "O" gauge layout. I hope to build a permanent layout in the garage attic if and when D2 gets her stuff out.....I'm not holding my breath.

View attachment 256271

That's rather coincidental - I watched that video yesterday!

 

[idlemarvel]

Mike, I don't run overhead wires yet but I intend to, not powered but just for show, indoors.

Ref your question 2, everything I have read on the subject says DCC works but the overhead contact is not reliable enough so it causes lots of problems with lost commands etc. And anyway why would you want to, except as an academic exercise, when you can run multiple locos using the two rails?

Ref your question 6, I think the question you are asking comes down to "can you use a common return rail for DC and DCC"? I am pretty sure the answer to that is no but I have been known to be wrong.

 

[dunnyrail]

Couldn't find a specific section relating to 'overhead' matters and as I've got more than one question I thought I'd put them all in one place. Over the years I've accumulated quite a number of locos, trains and trams with pantographs, bow collectors or trolley poles. To date I've relied on the 'imagine it's there' principle in respect of the overhead wires. Not long ago there was a rather animated discussion in the coffee lounge about the lack of realism when running locos with pans down (or up with no corresponding infrastructure). This got me thinking as I have accumulated a significant stock of related items - enough to do a complete installation on my layout.
Here goes:

1. Who runs stuff with the pantos up and actually in contact with the wires?
2. Who relies on power via the overhead? I saw recently it can be problematic with DCC.
3. Are there any associated problems with wear on either of the 'bits'?
4. What about (in particular PIKO) stock that have current collectors made of plastic? Do you replace them with metal ones or adopt a method similar to Nodrog who uses fishing twine to limit vertical movement which would prevent actual contact?
5. Who uses trolley poles (with wheels) on the LGB brass wires and are they troublesome?
6. Some of my locos are DCC (Kroks, Taurus, LCEs etc.) but I have a number of analogue LCE sets and trams. Is it feasible to have analogue running at the same time as DCC using one rail as the feed and the overhead as return if the chipped engines are track powered only?

No doubt there are other things I need answers to, but this will do for now.

Just as a matter of interest I have several masts with bases. I recently bought some solar powered lights from Poundland which came with two part brackets I did not need for the installation I required. With a small amount of packing/adaptation they look as if they will fill the role at a pound a pop rather than the £5 plus for LGB ones. No promises or guarantees about suitability, but I'm off to the shops to stock up on a few before they all go. For the uninformed the genuine LGB item is the light grey one.
View attachment 256264View attachment 256265View attachment 256266View attachment 256267View attachment 256268View attachment 256269View attachment 256270

We initially started the Ruschbahn with Pan Up and had pusherdownerers at Tunnels to enable access through said Tunnels and access to the Garage. Eventually I built full overhead for all the Visible Parts of the line but the pusherdownerers remained in place as much of the line was not visible and hence no need to string up the “washing Line” as I call overhead.

The myth that there are problems with DCC relates to using the Overhead as part of the Power Supply Chain as it were. It is not normally recommended by LGB, however if the Overhead is everywhere and the Locomotive is the other end of the supply with all wheels the same end if the Power Tram Style then all should be well. However this is not convenient for Steam or Diesel Outline Locomotives hence for G it is as well to regard the Overhead as “Dead” to juice. Though if the Pan is electrically isolated there is no reason not to use it as part of the supply to Buildings etc.

Needless to say the Lower Level of the Ruschbahn System in the Shed as the Fiddle Yard had sufficient space to allow Pans to remain up.

Another option is to limit the height that the pans can go up thus giving the view of Overhead where none exists, this system ought to work just fine for Pans, Bows and Trolleys. Needless to say your lowest Bridge would be the defining point of thie restriction.

Finally though, there is a magic to following a Pan on its trajectory running along the wires with the wire gently swaying from one side of the pan to the other and lowering plus lifting a little as it goes.

This link by a visitor will show lots of Overhead Running for you on the RB,

Note how fine the Overhead is, something not achievable with any of the Propriety Systems in any scale.

 

[schienenkönig]

By the way overhead wire for a tram is nessesary - my opinion.

I'm running my mobile tram layout with overhead wires. Until last year it was used to run two trams on the same track. But than my self made controller collapsed. I changed it during the exhibition into digital. The overhead wire is dead now.

At the moment I'm building eight new plastic boards for the layout. The track plan is changing.

And it will be digital. (Massoth and Digitrax, depending where it is set up.
My problem is the overhead wire. It must be mobile. The old one is wobbling and looks a bit shaby now.

Old layout. Self made brass masts with LGB overhead wire.

Centre area with Lgb masts.

When a show is finished I dismantle the overhead wires board by board. On the ends the wires where plugged into the LGB connectores. A friend of me, member of a model train society who installed overhead wires onto H0 and N layouts said, that the LGB overhead wire is to thick. The overhead wire by the German Railway has a diameter of round about 13mm². That means in 1:22,5 0,6 mm² thickness. So what? I do need an idea for making a mobile Overhead wire with no long working to install it.
Any ideas, please?
Peter who is melting in ther heat over Wuppertal.

 

[Paul M]

Overheads do seem to finish setting the Tramway scene, but getting the system robust enough for outdoork use must be a problem

 

[dunnyrail]

Overheads do seem to finish setting the Tramway scene, but getting the system robust enough for outdoork use must be a problem

Getting the wire robust enough for a portable line is an entirely different matter to that of a permanent line. Have to say I would not like to have to face up to what Peter is doing for shows. Certainly using LGB Wire will make his process easier but still a tricky process.

With the Ruschbahn we could rely on good soldered Joints and a degree of flexibility on the Pan Wire to Cross Wire interface and this was the key. I always wanted to have weights Operating the Pan Wire to keep it in tension, Andy insisted on Fence Screw Tensioners which worked well to a point, but when the wire expanded or contracted as it did in the heat / cold we did have the odd problems with drooping wire or broken Soldered Joints. Always noticed and fixed before a Running day. Strangely hits but Birds, Pigeons and walk into the wire events by Ducks or the household Cat tended to have little effect as the Overhead was generally robust enough to take those events.

Sadly all gone now, but that Vid brings back the happy memories of Operating and Constructing all that line.

 

[SevenOfDiamonds]

LGB have produced 'overhead electric' models in 3 specific eras:-

Pre-Digital: each model was fitted with a switch to allow power collection from two rails, or from one rail and the catenary wire. The model had to be put on the track in a specific direction (determined by the traction tyre, or by a red dot on the motor block), and it was thereby possible to use two controllers at the same time, one to operate a wholly-track powered loco, the other to operate a 'catenary-and-one-rail' powered loco.

Direct Decoder: (by which I mean a loco supplied as analogue, but with an interface to which a decoder can be fitted) As an analogue loco, the instructions say "This model can be operated with track power or with power from an
LGB catenary system. There is a power control switch located inside the streetcar" (so no different from "pre-digital") but it goes on to say (twice!) "CAUTION! If this model is equipped with a Multi-Train System decoder, it must not be operated with catenary power. Operate decoder-equipped locos with track power only" but doesn't go on to explain why!

Factory-fitted Decoder: The instructions for trolley-pole fitted models (such as 21832) say "Hint: The catenary poles of this model are non-operational". The instructions for pantograph-fitted models (such as 23460) say "CAUTION! This model may be powered with a catenary on analog layouts only. For operation with the digital Multi-Train System, the model must use track power. Otherwise, dangerously high voltages may result".

I am a member of the group operating the catenary-fitted "Whiteleaf" exhibition layout, that is sometimes operated as a tramway (analogue control) or as an electric railway (digital control). The catenary is not powered for either format. The catenary is mainly LGB's standard masts but, for greater rigidity, we use Peco code 83 rail (in three-foot lengths) in place of LGB catenary wire. When inverted, the code 83 rail fits perfectly into the LGB wire holders. Each board (or pair of boards) has it's own section of catenary where the rail is soldered into the wire holders. The double grooves in the wire holders provide a secure, yet removable, connection between the separate sections. The sections of catenary fold flat for transportation (posts and wires in the same plane). We primarily use pantograph (or bow collector) fitted trams and locos and they are in contact with the "wire". With two springs fitted, LGB pantographs can apply too much pressure on the "wire" for reliable operation, so one spring is removed. Bachmann trams are either fitted with pantographs instead of trolley poles, or run with their trolley poles clipped down (or restrained with thread). A fuller description was provided in the article "An overhead success" in the Winter 2014 copy of the G Scale Journal (Vol 28 No. 4).

I'm not sure whether I have answered any of ebay mike's questions but hope I have provided some interesting "food for thought".

All the best

David

 

[ebay mike]

Mike, I don't run overhead wires yet but I intend to, not powered but just for show, indoors.

Ref your question 2, everything I have read on the subject says DCC works but the overhead contact is not reliable enough so it causes lots of problems with lost commands etc. And anyway why would you want to, except as an academic exercise, when you can run multiple locos using the two rails?

Ref your question 6, I think the question you are asking comes down to "can you use a common return rail for DC and DCC"? I am pretty sure the answer to that is no but I have been known to be wrong.

LGB have produced 'overhead electric' models in 3 specific eras:-

Pre-Digital: each model was fitted with a switch to allow power collection from two rails, or from one rail and the catenary wire. The model had to be put on the track in a specific direction (determined by the traction tyre, or by a red dot on the motor block), and it was thereby possible to use two controllers at the same time, one to operate a wholly-track powered loco, the other to operate a 'catenary-and-one-rail' powered loco.

Direct Decoder: (by which I mean a loco supplied as analogue, but with an interface to which a decoder can be fitted) As an analogue loco, the instructions say "This model can be operated with track power or with power from an
LGB catenary system. There is a power control switch located inside the streetcar" (so no different from "pre-digital") but it goes on to say (twice!) "CAUTION! If this model is equipped with a Multi-Train System decoder, it must not be operated with catenary power. Operate decoder-equipped locos with track power only" but doesn't go on to explain why!

Factory-fitted Decoder: The instructions for trolley-pole fitted models (such as 21832) say "Hint: The catenary poles of this model are non-operational". The instructions for pantograph-fitted models (such as 23460) say "CAUTION! This model may be powered with a catenary on analog layouts only. For operation with the digital Multi-Train System, the model must use track power. Otherwise, dangerously high voltages may result".

I am a member of the group operating the catenary-fitted "Whiteleaf" exhibition layout, that is sometimes operated as a tramway (analogue control) or as an electric railway (digital control). The catenary is not powered for either format. The catenary is mainly LGB's standard masts but, for greater rigidity, we use Peco code 83 rail (in three-foot lengths) in place of LGB catenary wire. When inverted, the code 83 rail fits perfectly into the LGB wire holders. Each board (or pair of boards) has it's own section of catenary where the rail is soldered into the wire holders. The double grooves in the wire holders provide a secure, yet removable, connection between the separate sections. The sections of catenary fold flat for transportation (posts and wires in the same plane). We primarily use pantograph (or bow collector) fitted trams and locos and they are in contact with the "wire". With two springs fitted, LGB pantographs can apply too much pressure on the "wire" for reliable operation, so one spring is removed. Bachmann trams are either fitted with pantographs instead of trolley poles, or run with their trolley poles clipped down (or restrained with thread). A fuller description was provided in the article "An overhead success" in the Winter 2014 copy of the G Scale Journal (Vol 28 No. 4).

I'm not sure whether I have answered any of ebay mike's questions but hope I have provided some interesting "food for thought".

All the best

David

Thanks for that Dave and David respectively. While I have more than enough DCC equipped 'leccies to provide a fairly intensive service I was just curious if I could chuck in a couple of analogue jobbies on a casual basis rather than go to the expense of fitting more decoders. I note no-one has yet commented on the locos that have all plastic pantos and their suitability to be used as per the real thing. By-the-by, anyone intending to purchase the lights with brackets mentioned above - don't bother visiting Poundland on Great Yarmouth market place as I've temporarily reduced their stock to zero.

 

[perpetualnewbie]

I have seen a few models with well done overhead electric and really liked the look of it. I'm not sure if they were live or not.

With the DCC thing: I was idly wondering if it might make sense to use the overhead for "keep-alive" power rather than the DCC signal? So the tracks would be DCC, and the overhead provide plain DC. Less need to carry huge storage caps around, but the overhead is still doing a job. I assume I'd need a diode to stop the DCC controllers trying to "charge" the overhead wire, which could go quite wrong. However I've not seen someone suggest this so perhaps there is a good reason why not...

 

[PhilP]

As soon as you start throwing DC into the mix, you have the potential (no pun) for 'strange things' to happen in a DCC environment.

Differing DCC systems/decoders can interpret the presence of a DC potential to initiate different actions:
Some support 'brake on DC'. Some use a DC signal to initiate 'stop and reverse'.

The overhead only gives one 'leg' of the DC supply. - The other leg will be one of the rails.

Power from the overhead (of any flavour) will have a lot of inherent noise, as well as more frequent brown-outs (low volts) and drop-outs (breaks) in supply.


By all means use live overhead for DC if you wish, but I caution against it for a DCC system.

PhilP.

 

[Brixham]

I think the LGB no no with having live catenary and track is safety

Consider if the track is digital. Possibly 24 volts
And the catenary is analogue.....sharing a common rail Possibly another 24 volts.

Touching the catenary AND the non common digital rail could cause a shock with possibly around 50 volts.
I'm no expert, but isn't there safety legislation for exposed conductors over 48 volts.....especially with 'toys'

Many years ago pre digital era, LGB used to use a lower analogue voltage, say 18...so that would have reduced the maximum to around 36 volts between catenary and non common rail which is why it was deemed ok

Malcolm

 

[PhilP]

I think the LGB no no with having live catenary and track is safety

Consider if the track is digital. Possibly 24 volts
And the catenary is analogue.....sharing a common rail Possibly another 24 volts.

Not really.. - There is ELV' (Extra Low Voltage) regulation, but this was not in force when LGB first came out.

The DCC 'signal/voltage' is actually a balanced system, and alternate positive and negative values, either side of 0v. so no real potential to earth from either conductor. - This is a bit of a 'lie to children', but will do to keep it simple!
Either 'leg' can be earthed, and the potential to the other leg would be '24volts', but only for (approximately) half the time.

Under DC, you could run two loco's on the same section, IF one was track-powered, and the other used overhead.
It was even possible to run in opposing directions, BUT you had to have two totally separate controllers to do this.

 

[perpetualnewbie]

The DCC 'signal/voltage' is actually a balanced system, and alternate positive and negative values, either side of 0v. so no real potential to earth from either conductor. - This is a bit of a 'lie to children', but will do to keep it simple!
Either 'leg' can be earthed, and the potential to the other leg would be '24volts', but only for (approximately) half the time.

Hmm.

If DCC is going from +24 to -24, while DC is at +24 all the time, then the difference between the DC and DCC will switch between 0 and 48v if they are relative to the same ground... right? (hmm, I'll check that). 48v DC is pretty common - in power-over-ethernet and, if I recall rightly, some old phone equipment - without much fuss about safety. I expect it would tickle rather.

I can't see the DCC track serving as an adequate "0v" for a DC loco. Not that I've tried, it just looks like a bad idea.

 

[PhilP]

If DCC is going from +24 to -24, while DC is at +24 all the time, then the difference between the DC and DCC will switch between 0 and 48v if they are relative to the same ground... right?

NO!

The DCC signal is balanced (like balanced audio) NEITHER leg is 'ground'. - Unless your ground one of them, which will still work, but is (technically) a fault condition. They change polarity with respect to each other.

THE ANALOGUE (DC) VOLTAGE AND THE DCC SIGNAL/VOLTAGE MUST NOT BE FROM A COMMON SOURCE.

Two separate controllers..
The two controllers (one being the Central Station) could theoretically be fed from the same transformer, but you would need to know there was no 'common' path trough the controllers.

 

[Madman]

A well thought out and executed model catenary system is a thing of beauty. I've visited layouts where the modeler has built a prototypical catenary system with all the bells and whistles. If I didn't know it was a model, I'd think I was looking at the Pennsylvania Railroad's main lines.

And that brings up the topic of the mighty Pennsy. At the height of the Great Depression, the railroad made the decision to electrify it's main lines from Washington, DC to New York City and from Philadelphia out to Harrisburg, Pa. Every time I pass under or by those lines, I am in awe of the effort and expense it must have taken to accomplish the task.

 

[perpetualnewbie]

Hmm, there seems to be some misunderstanding here. I certainly am not expecting they can be mixed.

I was assuming that the DCC, being balanced, didn't give you a rail that sat at 0v and therefore that the difference between a DC conductor and DCC-powered track might indeed reach 48v as Brixham suggested (assuming both sets of voltages are relative to the same "zero", which I think is not a safe assumption). Sorry if I was unclear, but I can't quite connect what I think I said to what it looks like you're saying :-(

I'm not sure I understand what you mean about "analogue voltage and dcc voltage must not be from a common source" - I can't see how you would do that with off-the-shelf equipment. I assume if the DCC controller output and analogue controller output were connected it would at best trip some protections and more likely do some damage, but I don't think anyone suggested trying that.

 

[PhilP]

I'm not sure I understand what you mean about "analogue voltage and dcc voltage must not be from a common source" - I can't see how you would do that with off-the-shelf equipment. I assume if the DCC controller output and analogue controller output were connected it would at best trip some protections and more likely do some damage, but I don't think anyone suggested trying that.

I don't have the skills to draw diagrams on the computer in a reasonable time-frame, so this will have to be a thought-exercise..


These days, you tend to feed the output of a transformer (or a DC supply) into a 'controller' and the output of the 'controller'' is fed to the track.
'Controller' could be a DCC central station, or an analogue throttle, supplying a variable DC to the track.
Notionally, it would be possible to have a single transformer (could be a switched mode supply) feeding the inputs of both a DCC CS and an analogue controller. - This is the common source I am referring to. If there is a link here, it is possible (not definite) there could be a common path through the two controlling devices. As you say, this could cause some damage somewhere.

Now to the output voltages to the track/catenary:

The DCC signal/voltage is 24v peak-to-peak NOT +24v to -24v. This is a balanced signal, and you measure 'leg-to-leg' and not leg to ground.
The DC voltage will be (maximum) 24v. but again, unless 'we' make one leg 'grounded' it is just a potential between two wires. - It only by convention, we tend to call the negative/black wire 'ground'.
The black wire of the DC controller will only be at 0v. if we define the red wire as +24v. with respect to it. If you use the red wire as your reference, then the black wire is at -24v. with respect to that.
It is only when we either connect a wire to 'ground' / 'earth' / 'frame' or define that as a common-point it becomes 'ground'.

In our track and catenary scenario, we are using ONE rail for one leg of the DC only. - The other leg of the supply is the catenary.
The rail will float to some arbitary potential, but this doe not matter to the DCC system which is only looking between the two rails. The signal/DCC waveform will sit on top of this potential, but the decoder is looking at the difference between the two tracks with respect to each other, this will still be the 24v. DCC signal.

Having read that bacj, I have not explained it to well, but does it help?

 

[perpetualnewbie]

Thanks for the explanation of what you're thinking, PhilP, it does help. OK, my mistake was carelessly counting the DCC as peak voltage rather than peak-to-peak voltage, sorry. So the max difference you could get between it and 24vDC would presumably be 36, not 48v. Fair enough.

I wasn't really imagining trying to actually use the catenary to drive a DC train, just trying to reason my way through Malcolm/Brixham's safety idea. I hadn't dared imagine the scenario I now see you're outlining, where catenary + one rail forms a DC circuit and other rail + DCC ground forms a DCC circuit. I can see that that is electrically logically possible, I have no idea if off-the-shelf equipment could manage it. Half the voltage difference between rails compared to normal DCC though, right?

My earlier notion was a different scenario with no attempt to run DC trains. Again, sorry if unclear.