Why LGB catenary still requires track power?

[Mobi]

I don't use catenary myself but I understand it sill requires track power.
But why so? Why can't it run on catenary power alone like real life electric locos?

If this is to complete the circuit, how does real trains do it without having to power the tracks?
If you lay the track on soil with rails touching ground, is it not going to complete the circuit?

 

[Rhinochugger]

The rails provide the return current ............... in both cases.

On the 1:1 railways, the metal rails are supported by either timber or concrete sleepers.

There are some railway lines that use metal sleepers (not usually on main lines) and clearly, this wouldn't work with overhead or third rail electric power

 

[Diesel2000]

The model trains using catenary work in exactly the same way the real ones do. The metals wheels and rails of 1:1 trains pass the current back to the substation after pulling it off the overhead wire to power the motors. Model trains do the same. The actual ground does not complete the circuit.

 

[PhilP]

There are some railway lines that use metal sleepers (not usually on main lines) and clearly, this wouldn't work with overhead or third rail electric power

Yes it would, but it makes track circuit detection 'difficult'..
It is still a return path.

PhilP.

 

[korm kormsen]

If this is to complete the circuit, how does real trains do it without having to power the tracks?

the train does it with powered track. but people don't feel anything, because most are not able to step with one foot on the rail, while touching with the other the catenary.

being a model, or a 1:1 thing, it is all the same.
one cable (with DC the positive) runs through the catenary.
the other cable runs through the "earth".
it does not matter, if "earth" is just one rail, or the entire 1:1 globe.

here, in the 3rd world, we had a rural telephone, that worked with one cable only.
(at the central one cable was connected per steel wire on posts to the individual telephones, the other cable was stuck into the earth. at the individual phones it was the same: one contact to the steel wire, one contact stuck into the earth.
in 1984, when we built a 5 mile/8 km line for electricity (20,000V AC) from the next village with electricity to our village, we put up just one aluminium cable.
at the transformer to 220V AC in our village, there we got some fuses and a cable, that went into the earth till the groundwater level.
that worked for 30 years, till we got concrete posts with three cables.

in the model the good idea of this system is, that you can use two controllers (one connected as plus to the catenary, one connected as plus to one rail and both connected as minus to the other rail) and have two trains going at different speed (or even in different directions - for the Addams effect) on the same stretch of track.

 

[grizzmo]

Looking at RhB catenary closely you can see a return wire on the back side of all uprights. The cable with no insulator.
The rails are in the return circuit, in there system the rails and the ground wasn't a good enough return path all the way back to a tx and a dedicated return cable is also run.
Just to muddy the waters.