Voltage drop

[tigerburnie]

Forgive me if this asked/covered elsewhere, new to the site and still finding my way round it. Will you see significant voltage drop over a distance if using one supply per loop? I'm talking approximately 50 to 60 feet for each line. Thanks.

[johnb]

Very probably, losses through the fiishplates will be lot of the loss. Also depends on the rail you will be using, the current draw of the locos and so on.

I once had a DC HO layout with a 40ft run and needed to run extra feeds to the far side. I was using Peco code 100 track and heavy current draw locos (Athearns) in multiple.

 

Need a bit more info for the experts on here to assist properly, track being used, wiring sizes and what sort of locos

 

John

[DCMarvel]

There may be a bit of an obsession regarding voltage drops. Remember the James May Toy Stories series where he built a 10 mile length of track powered by car batteries every half mile or so and it worked. It was many times more than every 50 feet or so and locos ran fairly smoothly.

I know this is not to say overkill isn't a good idea, but too much overkill is also a waste of time, effort and money. If you can add more feeds at limited extra complexity and cost then it's probably worth it but more time and effort spent in careful track jointing such as filing burrs, making sure fishplates are a tight fit, gapping the joints neatly, probably eliminates the need to add extra feeds in the real world. Again a domestic fixed layout is a different beast to a sectional exhibition layout, where reliable operation is paramount as well as being robust.

Remember as well a 40ft loop is only ever 20ft from the power input at the furthest point. 20ft is nothing.

[kevinlms]

There may be a bit of an obsession regarding voltage drops. Remember the James May Toy Stories series where he built a 10 mile length of track powered by car batteries every half mile or so and it worked. It was many times more than every 50 feet or so and locos ran fairly smoothly.

I know this is not to say overkill isn't a good idea, but too much overkill is also a waste of time, effort and money. If you can add more feeds at limited extra complexity and cost then it's probably worth it but more time and effort spent in careful track jointing such as filing burrs, making sure fishplates are a tight fit, gapping the joints neatly, probably eliminates the need to add extra feeds in the real world. Again a domestic fixed layout is a different beast to a sectional exhibition layout, where reliable operation is paramount as well as being robust.

Remember as well a 40ft loop is only ever 20ft from the power input at the furthest point. 20ft is nothing.

James May used brand new track & brand new rail joiners. If the track is older & the rail joiners are loose, or they've got dirty (maybe from ballasting and glues got everywhere).

 

Some people think extra droppers are a wasted effort, but the OP has detailed a problem (voltage drop) which certainly wouldn't occur on a properly wired layout.

[tigerburnie]

Thanks for the replies, I am in the early stages of building, but trying to plan ahead, Peco code 100 is what I am using and with all new track and mostly brand new points(I am recycling some lightly used I already have).

[amdaley]

Thanks for the replies, I am in the early stages of building, but trying to plan ahead, Peco code 100 is what I am using and with all new track and mostly brand new points(I am recycling some lightly used I already have).

 

In that case you have the chance to do it properly first time so you won't have problems into the future.

Don't skimp on wire & track droppers because what you save just isn't worth it in the long run.

[michaelp]

In that case you have the chance to do it properly first time so you won't have problems into the future.

Don't skimp on wire & track droppers because what you save just isn't worth it in the long run.

Yes,  droppers to every piece of track and you wont go far wrong

[raymw]

If it were 1mm diameter copper wire, a fifty foot loop would give a voltage drop of about 0.6V for a 1Amp load.  Conductivity of nickel silver is much worse, never mind fishplates connection resistance, etc. No idea of resisitivity of ns, nor cross section of track. I'd use droppers and a // copper bus.

[BR60103]

Thanks for the replies, I am in the early stages of building, but trying to plan ahead, Peco code 100 is what I am using and with all new track and mostly brand new points(I am recycling some lightly used I already have).

If you're going to have points in the layout, you'll need to seriously consider extra feeds.

I would consider about 10 feet (3 lengths of flex track) a good target for one feeder. Extra bits around points.

 

I lost contact in a rail joiner that had been working for years when I ballasted last spring.

[Southernman46]

I find that light tapping with a small ball-pein hammer soon restores any dropped voltage to the correct shape ...........................

[tigerburnie]

As I'm not using DCC I will probably add isolation switches, especially in the station area, I will attempt to put a track diagram together and then see if you agree with my plan for the wiring. At present I have one dual Gaugemaster controller and plan to have extra for the goods depot/turntable area, at present there are no plans to add additional storage/fiddle yards, although I do have the luxury of space if needed to be added later. For those not familiar with the Leicester Great Central station, it is basically an island station with 3 through roads in both directions, a 4th track for goods/ carriage storage in each direction and a turntable, total length on my layout will be 16 feet long for the station area. This area will model from the 2 bow string bridges.  There will eventually be an oval approximately 10 feet wide and along the opposite side where a countryside section, just north of Whetstone station, where I grew up as a youngster in the 1950's and '60's.

[tigerburnie]

 Seems the only way I can post this is a pdf attachment. the thoughts were to attach supply to each end of the platform area on a ring main from each controlled side of my gaugemaster. The purpose of the isolation switches is if a train goes into platforms 1 to 4 engine first, the engines could be detached and another loco could attach at the rear and take the trains out again, as per the actual working of the original. The locos then either went to the opposite end of the station or, more commonly the engines went to the turntable and returned to where they originated.

Edited June 25, 2017 by tigerburnie

[tigerburnie]

I couldn't get the pdf to open I will have to try and put onto word and see if that is better. Seems this site won't let me bring anyrail items onto it, I will have to try something else.

Edited June 25, 2017 by tigerburnie

[tigerburnie]

Hopefully this file will work

[DCB]

I find in practical terms there is no voltage drop on plain track indoors but there is considerable rail joiner drop and it increases (dis) proportionately with load. A four loco lash up on 2 X 1 amps controllers will set dodgy rail joiners glowing so I dread to think what DCC with four on the front and four mid train helpers could do.

 

I would use a maximum of six pairs of rail joiners distance from one feed irrespective of length. Outside or DCC you can't trust rail joiners at all.

 

Speed Drop is much more noticeable with resistance controllers.  My only indoor speed drop is an insulated section on a lifting flap fed by wires "Bus Bar" from the controller and not fed through rail joiners and rails.

[kevinlms]

I find in practical terms there is no voltage drop on plain track indoors but there is considerable rail joiner drop and it increases (dis) proportionately with load. A four loco lash up on 2 X 1 amps controllers will set dodgy rail joiners glowing so I dread to think what DCC with four on the front and four mid train helpers could do.

 

 

8 loco on a train? Anyone doing such a thing, needs to take special recautions/wiring; relying on jail jointers would be plain asking for trouble.

 

Whether using dcc or plain dc, proper wiring and power sources would be essential.

[tigerburnie]

6 more turnouts arrived today, so the north end of the station area is loosely assembled and the cork stuck down, couple of things before I fix the track down(after first running a couple of locos up and down to make sure it works as I wish it to), a few have mentioned on other threads about soldering the rails together to improve power supply continuity, but do we not need to have gaps and the rails being allowed to move for expansion and contraction? Would I be better to use small wire loops?(I am using metre long flexible for most of the track, some will have to be trimmed to fit)

[smokebox]

Soldering track together is a bad idea if it is subject to temperature swings.

Rather than use short loops across the rail joiners I would simply solder wires on to each rail from a power bus.

 

With loops across the joiners you are relying on the rails to carry the current and the rails have more resistance than a power bus and short wires from a bus (droppers)

Edited June 27, 2017 by smokebox

[tigerburnie]

Couple of shots with a small pocket camera with the flash not functioning, I will get my proper camera on the job when there's more to look at. The track is just placed, if the rain continues I will have a bit more time on Thursday to start fixing in place. The plan is to use surface mounted point motors at the north end and I will have the control position at the south end and initially operate the points manually(purely  for cost saving for now). Once the complete oval is built and the rolling stock is at a better level, then I will return and automate the rest of the points and signalling last. I've just bought a 9f so the pocket money is spent for this week, just need about forty 16 ton mineral wagons to go behind it now. I should add that the track will be fitted properly with the large gaps in the sleepers sorted before fixing, this is very much a first fix.

Edited June 27, 2017 by tigerburnie

[tigerburnie]

I am about to run bus wires for the circuit and find, whilst I understand the desire to run as many extra feeds, I cannot with out switching each feed. If all lines are live I will have locos moving against points and causing derailments. On a busy weekend, there will be locos on pretty much all of the lines, passenger trains at the station, with through freight on the passing loops. I shall initially feed each end of the platform and see how this goes, I have done some initial trials with an A3 and a Britannia to ensure all the track and points are ok at the north end, awaiting delivery of more track and points as I have run out. I will also now be adding additional " passing loops" out side the station area, this to keep at least one main line open at all times in each direction.

[amdaley]

I am about to run bus wires for the circuit and find, whilst I understand the desire to run as many extra feeds, I cannot with out switching each feed. If all lines are live I will have locos moving against points and causing derailments. On a busy weekend, there will be locos on pretty much all of the lines, passenger trains at the station, with through freight on the passing loops. I shall initially feed each end of the platform and see how this goes, I have done some initial trials with an A3 and a Britannia to ensure all the track and points are ok at the north end, awaiting delivery of more track and points as I have run out. I will also now be adding additional " passing loops" out side the station area, this to keep at least one main line open at all times in each direction.

 

You don't switch the feeds / droppers, you switch the whole section as one.

In other words you run 2 bus wires (positive & negative) to each separate section & take droppers / feeds off those bus wires for that section.

So if you have 4 power sections you will have four sets of bus wires, one set to each section.

You then switch each section on or off according to what you wish to run. 

 

You could of course run a common return system but that's another story.

Edited June 30, 2017 by amdaley

[AndyID]

If it were 1mm diameter copper wire, a fifty foot loop would give a voltage drop of about 0.6V for a 1Amp load.  Conductivity of nickel silver is much worse, never mind fishplates connection resistance, etc. No idea of resisitivity of ns, nor cross section of track. I'd use droppers and a // copper bus.

 

I just looked it up and, as you say, nickel-silver (which has no silver in it) is a much poorer conductor than copper. The resistivity of a 64 Cu, 18 Zn, 18 Ni alloy is 16.6 times greater than copper. Because there is so much copper in nickel-silver alloy I always assumed it wasn't much different from pure copper but I was wrong (again).

[kevinlms]

I just looked it up and, as you say, nickel-silver (which has no silver in it) is a much poorer conductor than copper. The resistivity of a 64 Cu, 18 Zn, 18 Ni alloy is 16.6 times greater than copper. Because there is so much copper in nickel-silver alloy I always assumed it wasn't much different from pure copper but I was wrong (again).

That maybe true, but how relevant is it? Rail section is actually quite large and I've never noticed any loss of speed from on say one length of Peco's finest, from one end to the other. The idea of running a bus under the baseboard & putting droppers from each rail to the bus, is to overcome any loss, caused by loose or contaminated rail joiners, typically PVA getting in them, when track is ballasted.

 

A fifty foot loop, that would certainly be asking for trouble, without a decent size bus to actually carry the power.

[AndyID]

That maybe true, but how relevant is it? Rail section is actually quite large and I've never noticed any loss of speed from on say one length of Peco's finest, from one end to the other. The idea of running a bus under the baseboard & putting droppers from each rail to the bus, is to overcome any loss, caused by loose or contaminated rail joiners, typically PVA getting in them, when track is ballasted.

 

A fifty foot loop, that would certainly be asking for trouble, without a decent size bus to actually carry the power.

Some people might find it quite relevant, but it won't upset me in the slightest if you choose to ignore it.

[tigerburnie]

I will use the good old trial and test it formulae and see how it goes, at present the station is my priority, I am several weeks away from completing the entire loop, early testing yesterday with the new 9f shows that at present a power feed at either end of the station on each of the main lines as per my sketch, seems to be working well. I have not yet looked at the parcels/turntable area, this may have a separate controller and feed of it's own. Now in discussion with a supplier of mouldings for the parapets/arches for the viaduct for the station and approaches, seems my sizes are different to his mould, but the samples are excellent and will certainly give the station a fine finish.