Transitioning between 25kV AC and 3kV DC in Belgium.

[Nottingham59]

I'm on a Eurostar that has been diverted off it usual route because of problems with 25kV overhead supply. We're now running through Ath which has 3000V DC.

Can anyone tell me how trains make the transition? At the point where openrailwaymap says the supply changes, we stopped; all the fans went off; the train crept forward silently; stopped again; and then we started iff again on 3000V supply.

So it didn't coast across a neutral section. Do E320s have a traction battery to get across the gap? Or would the connecting line have been on a gradient so we could roll across?

 

[AndrewE]

So it didn't coast across a neutral section. Do E320s have a traction battery to get across the gap? Or would the connecting line have been on a gradient so we could roll across?

doubtful as it wouldn't work in the other direction!

 

[Fragezeichnen]

At some voltage transitions the voltage is changed in the overhead wires whilst the train is at stand with it's pantographs lowered, Aachen and Bad Bentheim are two examples.

On locomotive hauled trains the driver has to manually switch the "hotel" power supply to the train on and off and if there are a lot of others going on it can happen that it stays off even though the train has traction power. However, this seems unlikely on a Eurostar unit.

 

[martin2345uk]

Can't say what happened here as I don't sign Belgium, but no, our E320s do not have a traction battery so no way to move without overhead power.

 

[Nottingham59]

At some voltage transitions the voltage is changed in the overhead wires whilst the train is at stand with it's pantographs lowered, Aachen and Bad Bentheim are two examples.

Thank you. That's seems to be just what happened near Ath. Reverting to 25kV near Lille, we just passed through the transition point without a break. I assume we coasted with the pan down.

Can't say what happened here as I don't sign Belgium, but no, our E320s do not have a traction battery so no way to move without overhead power.

Thanks. I would have been surprised if they did. But I would never have guessed about switching the voltage in the catenary. I hope the interlocking for that switching process is robust!

 

[DanielB]

Looking at the maps the changeover near Ath from high-speed to regular line is going via a maintenance yard, so can imagine it's not really practical to put a full voltage changeover with neutral section in the middle of it. So I'd presume it's something like entering the yard with pantographs down, stopping under the 3 kV section and then raising the pantographs again.

Unfortunately the Belgian changeovers aren't really clear on open railway maps. Looking at a changeover in the Netherlands instead clearly shows the neutral section and even the related signs along the tracks for example, but in Belgium there's less detail.

 

[MarcVD]

The transition between 25 kV and 3 kV on line 1/2 is done with a neutral section that must be crossed by coasting. There is no switchable catenary. It's not located where openrailwaymap shows it but further west, near the service platform. You stopped before that, probably at the last signal before the divergence point, because the through itinerary could not be opened in time.

The section of high speed line beyond this point is closed for track renewal until end of next week. So every Eurostar Blue train goes the same way as you did. Eurostar red and TGV trains go via Mons and Antoing.

Line 1/2 does not go through a maintenance yard, just along it. That at least is correctly shown on Openrailwaymap.

 

[JonasB]

Thanks. I would have been surprised if they did. But I would never have guessed about switching the voltage in the catenary. I hope the interlocking for that switching process is robust!

I think so, because it's not that uncommon for border stations to have tracks that can switch voltage. It also has the benefit that the tracks can be used for more trains. E.g. at Aachen a track can be used for a German domestic train, and after the train depart the voltage can be changed and Belgian train can arrive at the same track.

 

[MarcVD]

I think so, because it's not that uncommon for border stations to have tracks that can switch voltage. It also has the benefit that the tracks can be used for more trains. E.g. at Aachen a track can be used for a German domestic train, and after the train depart the voltage can be changed and Belgian train can arrive at the same track.

Stations with switchable catenary are a thing of the past. They existed because most locomotives could use one system only so they had to be exchanged at the border. Multisystem locos were rare, expensive and difficult to maintain. They were reserved for the most prestigious passenger trains. Nowadays multisystem locos are abundant and even frequently used on freight trains. As a result, most stations with switchable catenary have disappeared. Belgium had one, Quevy, on the line between Brussels and Paris. Its gone, totally dismantled. France has one in Jeumont, on the line between Paris and Liège. It's still there but with its switching equipment out of order and unused. Aachen switchable tracks will be dismantled in 2026, replaced by a simple neutral section at the border. SNCB has 24 multisystem locos on order to work that out. There are no more tracks with switchable catenary in Belgium. And there has never been any on or along belgian HST lines.

 

[rvdborgt]

Stations with switchable catenary are a thing of the past. They existed because most locomotives could use one system only so they had to be exchanged at the border. Multisystem locos were rare, expensive and difficult to maintain. They were reserved for the most prestigious passenger trains. Nowadays multisystem locos are abundant and even frequently used on freight trains. As a result, most stations with switchable catenary have disappeared. Belgium had one, Quevy, on the line between Brussels and Paris. Its gone, totally dismantled. France has one in Jeumont, on the line between Paris and Liège. It's still there but with its switching equipment out of order and unused. Aachen switchable tracks will be dismantled in 2026, replaced by a simple neutral section at the border. SNCB has 24 multisystem locos on order to work that out. There are no more tracks with switchable catenary in Belgium. And there has never been any on or along belgian HST lines.

I'm not so sure it will be in 2026. They've been talking about it for at least 25 years now and every time something is published, execution has been delayed again.

 

[duesselmartin]

Thank you. That's seems to be just what happened near Ath. Reverting to 25kV near Lille, we just passed through the transition point without a break. I assume we coasted with the pan down.

Thanks. I would have been surprised if they did. But I would never have guessed about switching the voltage in the catenary. I hope the interlocking for that switching process is robust!

The pan does not have to be down. At a Power Break, a power switch is simply turned off, if needed the voltage system setted, when power is back, the power switch is turned back on.
That is done constantly on all lines.

 

[DanielB]

Though there are cases where a different pantograph is required for the different voltages. There it obviously needs to be lowered.

 

[MarcVD]

The pan does not have to be down. At a Power Break, a power switch is simply turned off, if needed the voltage system setted, when power is back, the power switch is turned back on.
That is done constantly on all lines.

It does have to be down. Otherwise it will create a shortcut between the live catenary and the neutral section, which is earthed. That will make the substation go into emergency and switch off.

 

[E94]

It does have to be down. Otherwise it will create a shortcut between the live catenary and the neutral section, which is earthed. That will make the substation go into emergency and switch off.

It does have to be down. Otherwise it will create a shortcut between the live catenary and the neutral section, which is earthed. That will make the substation go into emergency and switch off.

Neutral sections are usually floating, ie not connected to anything. This is so that a train can pass through, pan up, without shorting two different phases or sections together.

 

[MarcVD]

Neutral sections are usually floating, ie not connected to anything. This is so that a train can pass through, pan up, without shorting two different phases or sections together.

You have two cases :

In 15 and 25 kV systems, you have neutral sections that separate two catenary zones that might be powered by different phases of the 3-phase system. In that case, the driver does not have to change any setting in his locomotive, so there is no risk. In such situations, the neutral section can indeed be left floating, and if the pan is not lowered, nothing bad will happen. The lineside signals will say "interrupt traction" before the neutral section, and "resume traction" afterwards. On DC electrification systems, such cases are almost non existant.



But in any situation where there is a transition between two different electrification systems (which is the case we are discussing here), the neutral section is always earthed, in order to ensure that if the driver forgets to change his locomotive settings, the loco will not be damaged. The lineside signals in this situation are different and explicitely imposes to lower the pantographs. There are known cases that happened in Quevy where the driver did not pay attention and did not lower his panto, and this made indeed the two substations of Mons and Aulnoye to switch off in emergency.










Those exemples are from the french signals book but the belgian ones are similar.

 

[martin2345uk]

The examples of those "lower/raise Pantograph" sections on the high speed lines in the UK and France, at least those with TVM430 signalling, will automatically drop the train's pans if the driver fails to do it in time, I assume that is not the case everywhere...?

 

[Beebman]

Here's a video from a Czech YouTube railway channel showing a driver manually changing the locomotive voltage from 15kV AC to 3kV DC at the German/Czech border:

From a Dutch channel, a cab ride video from Heerlen to Aachen with shots of the driver changing voltage from 1.5kV DC to 15kV AC (from 8:48 to 10:03):

 

[Fragezeichnen]

The examples of those "lower/raise Pantograph" sections on the high speed lines in the UK and France, at least those with TVM430 signalling, will automatically drop the train's pans if the driver fails to do it in time, I assume that is not the case everywhere...?

Automatic Pantograph control is a specific(and possibly unique) feature of the TVM cab signalling system.

 

[MarcVD]

The examples of those "lower/raise Pantograph" sections on the high speed lines in the UK and France, at least those with TVM430 signalling, will automatically drop the train's pans if the driver fails to do it in time, I assume that is not the case everywhere...?

Yes on lines signalled with TVM it's entirely automatic. I have seen a video once showing it. It handles the fact that you need both pantos under 1500= and only the rear one under 25k~. With trains made with two MU'ed units, pantos are lowered and raised separately, as if they were independent. It's quite spectacular. I do not know whether it is also the case with ETCS. I will ask. There are several 3000/25000 junctions under ETCS 1 or 2 in Belgium.
It also works like that on the 1500/25000 junction on the RER B and D lines in the tunnel near Paris Nord. All other ones that I know are manual. In Aachen, the existing switchable tracks are not supposed to be passed at speed,
the voltage switch is done while the train is stopped with its pantos down.

 

[MisterT]

Automatic Pantograph control is a specific(and possibly unique) feature of the TVM cab signalling system.

It's not unique to TVM. ERTMS/ETCS has similar abilities, or at least it is able to provide the necessary information to the train (the train has to support it).
We use it on a daily basis in the Netherlands with our new ICNG trains (and previously with the failed Fyra V250 trains), where both the voltage change-over between 1.5 kV DC and 25 kV AC (and vice versa ofc), and the opening and closing of the MCB at the neutral sections are fully automated.
As soon as the train enters Belgium, though, the driver has to do everything manual again, because this feature is not implemented in the trackside ETCS on the Belgian side.

 

[MarcVD]

As soon as the train enters Belgium, though, the driver has to do everything manual again, because this feature is not implemented in the trackside ETCS on the Belgian side.

A belgian law passed after the 2010 accident in Buizingen imposes that all railway lines with passenger traffic must be equipped with ETCS before end 2025. This is an extremely tight schedule so I suspect that the reason for this is simply that they don't have enough manpower to address any non essential feature. I'm waiting for further info.

 

[MisterT]

The safety feature that the MCBs are opened and the pantographs are lowered if the driver doesn't do it themselves is, of course, still available, as that's a basic ETCS feature.
It's just the automatic switching to the different voltage and then raising the pantographs/closing MCBs again that can't be done by the train because it misses the information to do that.

 

[Thebaz]

As I understand it there is a voltage change on German/Czech border in the Elbe Valley (according to the European Rail Atlas 3.) When I recently traversed route on the European Sleeper there did not appear to be any changes in motion whilst the train crossed the border. What would have happened to effect the change here?

EDIT, just noticed the video above where that exact thing is shown.

 

[Beebman]

As I understand it there is a voltage change on German/Czech border in the Elbe Valley (according to the European Rail Atlas 3.) When I recently traversed route on the European Sleeper there did not appear to be any changes in motion whilst the train crossed the border. What would have happened to effect the change here?

EDIT, just noticed the video above where that exact thing is shown.

Since I posted that video I've found another one (German this time) which has some lineside shots of the border in the Elbe Valley that includes some footage of locos coasting with pan down under the voltage change section as can be seen in the video thumbnail. The loco can be seen lowering its pan at 8:02 and likewise one on a southbound freight at 9:22. The middle part of the video has some clear shots of the voltage change signs.

Video description using Google Translate:

System change at the system separation point Schöna - Dolní Žleb | D - CZ | AC-DC | Elbe Valley - The only electrified railway border crossing between Germany and the Czech Republic is in the Elbe Valley. It has some operational peculiarities. You can see the operation and its processing here in the film.