Electric trains using unelectrified track

[Bald Rick]

I understand the selector also determined power consumption limits. For example the GV(Grande Vitesse / high speed) position allows the train to draw full power from the 25kV AC supply, whereas the BR setting limits the amount of power drawn by the train and affects acceleration. Similarly the F (France) 25kv setting allows a greater power draw than BR 25kV settings, but not as much as in the GV setting.

AIUI, also the relevant signalling system (TVM, AWS/TPWS, KVB, etc)

 

[Railperf]

The same situation applies at the border station of Modane in the French Alps where Italian locomotives drop their pantographs prior to the place where voltages change from 3000 volts dc to 1500 volt# dc and coast into the station or freight yard and await haulage back to Italian electrified territory.

Again the same applies at Brenner station where the ÖBB, Austrian railways 15kv ac meets the Italian system 3000 volts dc.

At Modane, Italian 3kV DC locos can raise their pantograph under the 1.5kV DC supply but the loco effectively only has half the power. Of course the panto is lowered through the transition section.
Tri voltageTGV's switch from their 3kv DC pantographs to the 1.5kV DC pantographs after lowering the pantographs through the neutral section.
There was a time when whole station at Ventimiglia was wired at 1.5 kV DC to allow French dual voltage 1.5 kV DC/25kV DC locos to run in and out of the station. It meant Italian rolling stock would run in and out of the station at half power.

 

[JWK]

Back in 2010, travelling from King’s Cross to Edinburgh on a class 91-hauled set, we came to a halt somewhere south of St Neots. After a lengthy stop, the train manager announced that the train in front had reported damage to the OHLE and we had now been cleared to coast across it. However, as we had stopped quite close to the damaged section, we would need to reverse about four miles (wrong line!) so we could then go forward again, getting up sufficient speed to coast through. All of which we subsequently did, with some truly impressive acceleration after we had performed the reversal and still going at decent speed when the power came back on. Arrival into Waverley was barely 90 minutes late, which was pretty good in the circumstances.

 

[merry]

At Modane, Italian 3kV DC locos can raise their pantograph under the 1.5kV DC supply but the loco effectively only has half the power. Of course the panto is lowered through the transition section.
Tri voltageTGV's switch from their 3kv DC pantographs to the 1.5kV DC pantographs after lowering the pantographs through the neutral section.
There was a time when whole station at Ventimiglia was wired at 1.5 kV DC to allow French dual voltage 1.5 kV DC/25kV DC locos to run in and out of the station. It meant Italian rolling stock would run in and out of the station at half power.

Point of pedantry: half voltage means 1/4 (not half) power if the same resistance...
This is also done for Belgian 3kV dc trains running from Anvers to Roeselare just over the Dutch border. Holland uses 1kV5 so they roll into Roeselare quite slowly, albeit under power.
As an aside, the Belgian stock used is old, tired, vandalised and tatty. Like it is kept going to allow such services to continue. Modem stock likely isn't as tolerant of supply conditions...

 

[Acathater]

Weren't the Bulleid/Raworth Co-Co booster electrics supposed to be able to venture into an unelectrified siding and bring back a wagon or two, using the rotating mass of the booster sets to generate?

From what I've read the capability was more like the ability to cross breaks in the conducting rail e.g. at level crossings, and also the ability to boost starting tractive effort

== Doublepost prevention - post automatically merged: 22 Apr 2026 ==

Certainly could have been - at the time I wouldn’t know the difference. But were 4TCs often seen that far east? As you put, they were usually used on the line to Weymouth.

the TCs got as far as Bristol and Exeter at times, standing in for the regular stock. Sometimes they turned up on the weekend Brighton-Exeters so it wasn't unknown for them to wander

 

[GraphitProjekt]

I understand the selector also determined power consumption limits. For example the GV(Grande Vitesse / high speed) position allows the train to draw full power from the 25kV AC supply, whereas the BR setting limits the amount of power drawn by the train and affects acceleration. Similarly the F (France) 25kv setting allows a greater power draw than BR 25kV settings, but not as much as in the GV setting.

Yeah makes sense. Are the power draw settings for "HS" mode the same as LGV? I found another picture where you can see the French DC setting all the way round the back, which I feel like was only fitted to certain units and not all of them, but I could be wrong.

The same applies with the signalling

Interestingly, I've read the Channel Tunnel also has a system of 21kV (3 phase) powerlines for all non-traction purposes using apparently 175 stepdown substations!
Similar arrangement on HS1 but at 11kV. I think this is standard way of doing things for European Railways that we don't really do (other than LUL/TfL powersystem)

 

[Sean Emmett]

They did see some use on special workings at times, but yes certainly out of their normal way.

Not impossible though, I mean a 319 went part way into the Channel Tunnel for instance!

re 33/1 on Ashford - Hastings. I have a clear recollection of a 33/1 hauling a 4VEP (not a 4TC) and not getting the braking quite right and, er, missing the platform at Ham Street. One of 4 instances I have noted this happening (class 150 at Oldfield Park, class 507 missing a stop on the Southport line and a Pacer missing Edale on the downgrade and getting permission from the signalman to set back).

in Europe there are still stations where electric locos have to pan down and coast to the far end of the platform and await rescue. Seen this as recently as Sep 2025 at Dobova on the Slovenia / Croatia border (3000V DC to 25kV AC).

Edit - it's Croatia to Slovenia. Arriving 25kV loco gets shoved back from whence it came.

 

[GraphitProjekt]

I saw some years ago that the normal situation is for the entire Eurotunnel system to be fed from France with the UK feed as a backup because French power is cheaper.

Just found a document that suggests that switching to French derived traction power allowed Eurotunnel to reach internal carbon footprint goals. Probably that and it's cheapness. Amusingly, anywhere from 6 to 10% of GB's demand is made up by French imports. And considering Eurotunnel (and some of HS1) is connected to Sellindge 400kV substation, it probably French energy would end up flowing back into Eurotunnel anyway but at UK price, since Sellindge also receives 5 of the 6 interconnectors

 

[izvor]

A little off-topic, many years ago when the 377s were new, I was travelling on one that failed at Woldingham, pretty sure it was the last up service of the day. After several abortive restarts the driver was given permission to coast all the way to Sanderstead (3 statons, all downhill) in service but without power, where the train was met by mechanics who fixed the problem. A very strange and novel experience - no motor or aircon noise, and only failsafe lighting. Would this be allowed now?

 

[Recessio]

For the same reason the major power transmission cable between UK and France under the Channel converts to DC on one side, and is reconverted back to AC of the recipient country on the other side. For some reason it needs to be more complex than a normal neutral section.

It's actually more about capacitance for underwater cables, HVDC is generally the better option as the losses from AC outweigh the higher equipment cost on shore for DC. A side effect of this is that the UK grid isn't synchronised with the European grid, but it's not the main goal

 

[Railperf]

AIUI, also the relevant signalling system (TVM, AWS/TPWS, KVB, etc)

thinking about it, the BR setting would also set the speedo display to MPH rather than km/h - all the others are km/h. Class 395's also do the same for DC setting. While the 25kV position sets km/h for HS1

 

[martin2345uk]

Are the power draw settings for "HS" mode the same as LGV? I found another picture where you can see the French DC setting all the way round the back, which I feel like was only fitted to certain units and not all of them, but I could be wrong.

Maximum deliverable power is 12200kW on both HS and GV setting according to the manual

 

[edwin_m]

On this topic, the track over the lifting section of the Kingsferry Bridge on the Sheerness branch is devoid of third rail, meaning trains have to coast across it.

On the London area DC lines , we once had a 3 car ECS 313 , who accepted the wrong route at Gunnersbury and who made a valiant attempt at reaching the District line , luckily he failed , and as it was causing some issues to LUL they very kindly sent a pair of battery electric locos to return it to its proper working environment ! - very embarrasing to all !

Transitions between the "proper" LU fourth rail (power rails above and below ground potential) and fourth rail on NR (power rail above ground potential, fourth rail bonded to running rails) need a gap at least one coach long so the rails at different potentials aren't connected by the cables on the train that link the collector shoes. On Underground stock the shoes are only connected within the same coach, but National Rail units have electrical connection through the whole unit. It's possible these were disconnected on the 313 in DC mode, which was originally specified for the Northern City tunnels.

 

[GordonT]

The original Glasgow suburban electrification scheme was dual-voltage system (6.25kV AC / 25kV AC) with neutral sections at the changeover points. The automatic changeover process seemed not to specifically require drivers to move the power handle to Off whilst negotiating the dead section (although most did) nor did the pantographs lower. The bang which sounded like the pan lowering was the breaker opening. Very occasionally with a faulty unit the breaker failed to re-close after the dead section. (Relying on my memory for about 60 years ago and with minimal technical knowledge).

 

[Rescars]

From what I've read the capability was more like the ability to cross breaks in the conducting rail e.g. at level crossings, and also the ability to boost starting tractive effort

Whilst the booster was intended to deal with the normal breaks in the conductor rail, surely someone experimented, either officially or unofficially, to find out how far a Bullied/Raworth Class 70 could travel on booster power alone. A suitable test location might have been in an OLE equipped yard with loco working with its panto down.

 

[hexagon789]

Whilst the booster was intended to deal with the normal breaks in the conductor rail, surely someone experimented, either officially or unofficially, to find out how far a Bullied/Raworth Class 70 could travel on booster power alone. A suitable test location might have been in an OLE equipped yard with loco working with its panto down.

I believe a "70" could go up to 10 mins off the booster alone, even hauling a small load, albeit very slowly due to the reduced motor voltage, but likely fine for a brief shunt in/out of a siding.

 

[saismee]

The bang which sounded like the pan lowering was the breaker opening. Very occasionally with a faulty unit the breaker failed to re-close after the dead section.

I believe I heard this still happens occasionally everywhere. Somebody correct me if I'm wrong, but I think I remember reading about a class 90 passing a signal at danger due to the driver being distracted by a VCB fault.

 

[jumble]

I seem to recall reading ( or seeing on a program) that the Preserved London Underground 1938 Stock coasts into the Acton Depot after rail tours
There will be better placed forum members who can confirm/deny
I certainly remember reading that when the A stocks were making their final journeys to Rotherham via Northwood they coasted the last bit into the Northwood siding

 

[Acathater]

I believe I heard this still happens occasionally everywhere. Somebody correct me if I'm wrong, but I think I remember reading about a class 90 passing a signal at danger due to the driver being distracted by a VCB fault.

The TPE electric sets do it going north on the WCML at the section break around Garstang. Usually a double bang, followed by a single

 

[saismee]

The TPE electric sets do it going north on the WCML

They have VCB faults or pass signals at danger?

 

[Acathater]

They have VCB faults or pass signals at danger?

Go BANG!
Which I hope is just due to the VCB fault.....

 

[GraphitProjekt]

The original Glasgow suburban electrification scheme was dual-voltage system (6.25kV AC / 25kV AC) with neutral sections at the changeover points. The automatic changeover process seemed not to specifically require drivers to move the power handle to Off whilst negotiating the dead section (although most did) nor did the pantographs lower. The bang which sounded like the pan lowering was the breaker opening. Very occasionally with a faulty unit the breaker failed to re-close after the dead section. (Relying on my memory for about 60 years ago and with minimal technical knowledge).

Many of the first types of 25kV AC EMUs to be built were dual voltage with 6.25kV. Not just the Glasgow area but also in Anglia with GEML, LT&S and the Chenford scheme (NE London). Since 50Hz AC and neutral sections in general were new to BR, the APC system designed to manage neutral sections was completely compatible with electromechanical voltage sensing equipment on the dual voltage trains. So from the driver's perspective it didn't really matter whether a neutral section was just between supplies or between voltages. There is a rough explanation of how it worked on the Wikipedia article for GEML

 

[contrex]

There was a time when whole station at Ventimiglia was wired at 1.5 kV DC to allow French dual voltage 1.5 kV DC/25kV DC locos to run in and out of the station. It meant Italian rolling stock would run in and out of the station at half power.

3000 V officially inaugurated 13 November 2025

Have the SNCF EMUs been modified to use 3000V? And what about locos?

- video here -

 

[saismee]

Go BANG!
Which I hope is just due to the VCB fault.....

Probably not even a fault, that's just the sound they make. It's quite loud if you're sitting in the wrong (right ) part of the train.

 

[Acathater]

Probably not even a fault, that's just the sound they make. It's quite loud if you're sitting in the wrong (right ) part of the train.

Usually results in a few scared faces, to which it's fun to say "Don't worry - they always do that..."

 

[saismee]

Usually results in a few scared faces, to which it's fun to say "Don't worry - they always do that..."

I see it a lot when the pan drops at the aforementioned changeover at Stowmarket. Sounds a lot like something hitting the roof of the train .

Edit: the Stowmarket thing was actually in another thread. Whoops!

 

[Dstock7080]

I seem to recall reading ( or seeing on a program) that the Preserved London Underground 1938 Stock coasts into the Acton Depot after rail tours
There will be better placed forum members who can confirm/deny
I certainly remember reading that when the A stocks were making their final journeys to Rotherham via Northwood they coasted the last bit into the Northwood siding

That is certainly correct on both counts.
When i started at Acton Town, the space occupied by the present Museum Depot was full of electrified sidings.
‘A’ Road is electrified until the Museum gate.

 

[Taunton]

3000 V officially inaugurated 13 November 2025

Have the SNCF EMUs been modified to use 3000V? And what about locos?

One wonders why such an investment, as Italian stock always seemed to run quite satisfactorily on the half voltage for the mile or so out to the changeover, and French stock has pretty much all been built dual voltage for a generation now. Is there some sophisticated switching arrangement to set individual tracks at different supplies?

 

[Elecman]

The TPE electric sets do it going north on the WCML at the section break around Garstang. Usually a double bang, followed by a single

They will do that at all the neutral sections on the route not just at Catterall Feeder

 

[Tetragon213]

Rather (in)famously, a Class 90 did once make it to Llandudno Junction. 90039 apparently really fancied a trip to Holyhead!

AIUI, they forgot to detach the 90 off the back of a VT service to Holyhead at Crewe. I can only imagine the driver in the 47 that was scheduled to take it to Holyhead must've been wondering "why does my train feel 100 tonnes heavier than usual?"