Multi-System Trains

[ryan125hst]

I’ve been interested in trains in Europe over the last few days and have been surprised at just how many different voltage standards and signalling systems there are, with many TGV and ICE trains having compatibility with multiple systems. Taking the latest ICE3 NEO as an example, they are compatible with 1.5kV DC, 3kV DC, 15kV 16 2.3 Hz, and 25kV 50 Hz.

From an AC point of view, it is simple to have a train that supports multiple AC voltages as they will use different windings within the transformer to step down the voltage to the required secondary voltage. However, I was wondering what DC bus voltage is used and therefore how the two different DC voltages are handled.

This PDF from Siemens regarding the Velaro units they supplied to Russia suggests they have a 3kV bus (AC or DC).

However, looking at this brochure from Siemens regarding their auxiliary converters, the high speed models have a nominal voltage of 1.5kV DC. Are the convertors used on the ICE3 NEO and Eurostar e320 versions that support both 1.5kV DC and 3kV DC? Or is the train also fitted with large DC to DC convertors to provide the correct DC voltage?

Some TGV sets are also tri or quad voltage so the same question for these as well.

 

[Fragezeichnen]

The ICE3neo has no single universal high voltage bus. Each train consists of two independent traction packages spread across 4 cars, each with a single transformer, two traction converters and two auxiliary power supplies. Under AC, or 3000V DC there is a bus which connects the power direct from the pantograph between the two halves of the train. Under 1500V there is no interconnection and both pantographs must be used to achieve full traction power. Regardless of voltage the power runs first to the transformer car, then further as either 3kV AC, 3kV DC or 1500v DC to both traction converters where it is rectified to DC if necessary and then powers the traction inverters and auxiliary power converters.

The auxiliary converter converts from either 3000v or 1500v DC to low voltage buses of 440v AC 3 phase(for HVAC and probably catering) from which is derived 230v AC(mainly for power sockets) and also 110v DC(for charging the batteries).

 

[ryan125hst]

Thanks Fragezeichnen. I have been looking at the ICE3neo and our e320 Eurostars which share a very similar arrangement. I understand the AC pantograph is located on the 4th car and the transformer is in the 2nd car and so a 25kV bus exists to supply the transformer (with a 25kV bus also existing to coach 5 to power the other half of the train). Looking at the diagram from Valero RUS, it seems the same cables are used for the output of the transformer at 3kV AC or from the DC pantograph at 3kV DC or 1.5kV DC. It makes sense now as to why the power is going through something labelled as TSR in the diagram, which presumably is the traction converters.

The arrangement shown on that diagram is a 380V 50Hz socket but also 440V 60Hz within the train and 230V 60hZ single phase from that. Is this the case in Germany, where presumably the 380V 50Hz is a shore supply (which would be 400V 50Hz in Europe) but the train operates usually at 440V 60Hz? It's odd that it operates at 60Hz given the 50Hz European standard.

Overall, it means that the Valero has five power buses:

1. 25kV bus between coaches 2 and 4, plus connecting to coach 5 to power the other half of the train.
2. 1.5kV DC / 3kV DC / 3kV AC feed to the traction inverters.
3. 1.5kV DC / 3kV DC feed to auxiliary inverters.
4. 440V 60Hz three phase for HVAC/Catering.
5. 110V Battery powered lighting and I presume control circuits.

It also shows separate 220V 50Hz supplies in each coach - Is this the inverter for the power sockets in each coach being provided from the 110V DC supply?

You mention that under 1.5kV there is no connection between the two halves of the train. Is it possible for the two halves to be connected together under 1.5kV in the event that one of the two DC pantographs is damaged? I guess it would have to proceed at half power, but it would allow the train to limp to a suitable place to get the passengers off etc.

How many compressors are there per half set and where are they? I presume they are powered from the 440V three phase bus also?

 

[Fragezeichnen]

Yes, there are also inverters which turn 110V DC into 400V 50 Hz 3 phase, so this where the domestic power would be derived from, and indeed not the 440V 60Hz AC. The shore supply used during maintenance is 670V DC- I assume the auxiliary converter does an initial step down from 3kV/1.5Kv DC to 670V DC before producing the various other voltages. There are two compressors, in the two adjacent "middle coaches" 4 and 5, powered so far as I know from 440v.

The only difference under 1.5kV is that one pantograph cannot power all four traction converters, only the two in it's half of the train. In the event only one half the train has power from the pantograph then only half the traction motors would be powered, and and HVAC load would be reduced as the overall power available on 440v/400v would be limited.

 

[FormerBritInMe]

I guess even more complex would be the original Eurostars pre-HS1 when they had to run on the national network to Waterloo and therefore had to have 600V DC capability along with everything else. Plus AWS equipment.

 

[SephenWorceste]

I too am surprised how many different power and signalling systems there are in Europe. Even in the same country and even just on intercity lines. I suppose they were all originally separate organisations (and still are).

The current Europe wide rail network has been built partially by building new infrastructure with common systems. Often it has been done by building trains with all these multiple systems. That option is probably often initially cheaper.

I remember gauge changing trains between France and Spain. Not sure if that is still done. Perhaps track gauge is more common even if loading gauge still is different.

 

[AdamWW]

I remember gauge changing trains between France and Spain. Not sure if that is still done. Perhaps track gauge is more common even if loading gauge still is different.

Between France and Spain, not any more (at least for passenger trains).

But since Spain now has a mixed standard gauge (high speed line) and Iberian gauge (conventional lines) network, there are many gauge changing trains in operation on domestic journeys.

 

[ryan125hst]

Yes, there are also inverters which turn 110V DC into 400V 50 Hz 3 phase, so this where the domestic power would be derived from, and indeed not the 440V 60Hz AC.

I presume you mean turn 110V DC into 230V 50Hz single as I doubt there would be the capacity to supply the three phase loads from the battery?

The shore supply used during maintenance is 670V DC- I assume the auxiliary converter does an initial step down from 3kV/1.5Kv DC to 670V DC before producing the various other voltages.

That's an interesting voltage, is there a reason why this is used? I guess it feeds the auxiliary converter DC bus and not the input bus to the traction inverters?

There are two compressors, in the two adjacent "middle coaches" 4 and 5, powered so far as I know from 440v.

That makes sense, one per four coach half set. The Eurostars will have four compressors as they are made of two 8 car half sets.

The only difference under 1.5kV is that one pantograph cannot power all four traction converters, only the two in it's half of the train. In the event only one half the train has power from the pantograph then only half the traction motors would be powered, and and HVAC load would be reduced as the overall power available on 440v/400v would be limited.

That's what I would expect, it would have to operate in a failure mode to limp along but would still be able to move.

I guess even more complex would be the original Eurostars pre-HS1 when they had to run on the national network to Waterloo and therefore had to have 600V DC capability along with everything else. Plus AWS equipment.

It's 750V DC out of Waterloo and other third rail areas in the south. Class 373's could run on 750V DC, 3000V DC and 25kV 50 Hz so only three voltages, and the 750V third rail shoes were removed when St Pancras opened. The signalling is linked to the mode selector switch so the power and signalling mode is switched at the same time as can be seen in this video:

I too am surprised how many different power and signalling systems there are in Europe. Even in the same country and even just on intercity lines. I suppose they were all originally separate organisations (and still are).

Yeah I was very surprised by this as well, and even more surprised by a lack of trying to standardise these years ago. We are heading towards signalling standardisation now with ETCS but it'll take a few decades. There doesn't seem to be any desire to do the same with electrification standards!

 

[Gag Halfrunt]

The Czech Republic has a mixture of 3kV DC and 25kV AC, but is now gradually converting DC lines to AC.

 

[Gordon]

I too am surprised how many different power and signalling systems there are in Europe. Even in the same country and even just on intercity lines. I suppose they were all originally separate organisations (and still are).

The number of different 'systems' isn't all that great when looked at statistically.

There are only four main electrification systems across Europe: 1.5kV dc, 3 kV dc, 15kV ac and 25 kV ac
There are three main track gauges on main lines: 'standard gauge', Iberian gauge (5ft 6) and Russian gauge (5ft) plus in addition two main 'minor railway' gauges, 1000mm and 750mm

All this in a total network length of around over 200,000km just in the EU

 

[Trainbike46]

The number of different 'systems' isn't all that great when looked at statistically.

There are only four main electrification systems across Europe: 1.5kV dc, 3 kV dc, 15kV ac and 25 kV ac
There are three main track gauges on main lines: 'standard gauge', Iberian gauge (5ft 6) and Russian gauge (5ft) plus in addition two main 'minor railway' gauges, 1000mm and 750mm

All this in a total network length of around over 200,000km just in the EU

And there is increasing standardisation towards the standard gauge track gauge, in that both the Baltic States and Spain are building new lines with the standard gauge. Similarly, there is a move towards 25kV AC (50Hz), with new lines across almost all of Europe following this.

 

[AdamWW]

Similarly, there is a move towards 25kV AC (50Hz), with new lines across almost all of Europe following this.

Though Germany and Austria use 15 kV AC 16.7 Hz on new lines I think, which is a considable exception.

 

[JonasB]

The number of different 'systems' isn't all that great when looked at statistically.

There are only four main electrification systems across Europe: 1.5kV dc, 3 kV dc, 15kV ac and 25 kV ac

And multisystem locos and EMUs are pretty common today. So it's really not a big problem in reality.

Though Germany and Austria use 15 kV AC 16.7 Hz on new lines I think, which is a considable exception.

As well as Sweden, Norway and Switzerland.

 

[zwk500]

And there is increasing standardisation towards the standard gauge track gauge, in that both the Baltic States and Spain are building new lines with the standard gauge. Similarly, there is a move towards 25kV AC (50Hz), with new lines across almost all of Europe following this.

AIUI the standardisation on 25KV AC (50Hz) standard gauge is pretty much only for high-speed lines. Rail Baltica is deliberately not inter-operable with the legacy network for geopolitics reasons. There's the Betuweroute but that being electrified at 25KV AC was pretty much a warning as to why you shouldn't go for 25KV AC if you don't connect to it at either end.

I'm not aware of any plans in Spain for gauge conversion. Belgium is converting some lines to 25KV AC where they work through to France but I don't think they're planning wholesale conversion any time soon.

 

[AdamWW]

AIUI the standardisation on 25KV AC (50Hz) standard gauge is pretty much only for high-speed lines. Rail Baltica is deliberately not inter-operable with the legacy network for geopolitics reasons. There's the Betuweroute but that being electrified at 25KV AC was pretty much a warning as to why you shouldn't go for 25KV AC if you don't connect to it at either end.

I'm not aware of any plans in Spain for gauge conversion. Belgium is converting some lines to 25KV AC where they work through to France but I don't think they're planning wholesale conversion any time soon.

As above Czechia is gradually converting existing lines to 25 kV.

I think (but I find Spanish railways rather confusing) new electrification in Spain on existing lines is 25 kV.

Certainly Salamanca is electrified at 25 kV despite being Iberian gauge - which I think results in diesel trains running fully under the wires due to a lack of dual voltage trains.

 

[MarcVD]

Different electrification systems exist because not all countries started electrification at the same time. Electrification techniques evolved with time, and each country picked the system that was state of the art at the time they started.

Standardization at international level was not considered, because electrified international relations were absolutely not envisioned at that time.

Once a system is chosen, its cost is such that it is impossible to convert to another system, the costs involved can almost never be recouped. Today, however, multisystem locos make the coexistence of different systems a non issue.

Today, the 25 kV system is clearly the best, at least for industrialized countries : places where the electrical grid is weaker might have problems with the unbalanced load that the 25 kV system creates. Therefore, most new lines are created today with this system, even in places where other systems are dominant. On the other hand, 3 kV DC and 15 kV 16,7 Hz are still perfectly fit for the job and still continue to be extended. 1,5 kV DC however, with the advent of 6MW locomotives, is not fit for the job anymore. But even in this situation, Dutch railways have abandoned the idea to convert their network to 25 kV, and even the conversion to 3 kV DC, much cheaper, is still largely in doubt.

 

[AdamWW]

Once a system is chosen, its cost is such that it is impossible to convert to another system,

I think impossible is probably a bit strong here, given that Czechia is actively converting existing lines to 25 kV.

Different electrification systems exist because not all countries started electrification at the same time. Electrification techniques evolved with time, and each country picked the system that was state of the art at the time they started.

There are of course examples where countries have more than one electrification system even on main line rail (and not only because of changing borders since electrification).

 

[stuu]

I'm not aware of any plans in Spain for gauge conversion.

They have been using gauge-convertible sleepers for years, possibly decades, when renewing tracks. The extension of the high speed line to Almeria involves rebuilding the existing line west of Murcia and converting it and the branch to Aguilas to standard gauge, which will be the first significant conversion. There isn't any wider plan in existence though

 

[zwk500]

They have been using gauge-convertible sleepers for years, possibly decades, when renewing tracks. The extension of the high speed line to Almeria involves rebuilding the existing line west of Murcia and converting it and the branch to Aguilas to standard gauge, which will be the first significant conversion. There isn't any wider plan in existence though

Ah, that's very interesting. Gauge-convertible sleepers is one thing but actually converting a line is quite a significant step.

 

[MarlowDonkey]

Once a system is chosen, its cost is such that it is impossible to convert to another system, the costs involved can almost never be recouped.

The UK has converted its 1500 DC electrification to 25kv AC. Admittedly this was just the suburban lines out of Liverpool Street and what was left of Woodhead route after closure. The other experimental systems of 100 years ago were also converted.

Wholesale conversion of the UK's third rail systems has never really been planned other than in fantasy schemes.

 

[AdamWW]

Ah, that's very interesting. Gauge-convertible sleepers is one thing but actually converting a line is quite a significant step.

I have read (and can't remember where and I have no idea if it's true) that once they've been installed a while it would be very difficult to use them as such - something about the rubber in the mounting holes?

It is presumably in any case useful not to keep supplies of two different types of sleeper.

== Doublepost prevention - post automatically merged: 4 Sep 2025 ==

The UK has converted its 1500 DC electrification to 25kv AC. Admittedly this was just the suburban lines out of Liverpool Street and what was left of Woodhead route after closure. The other experimental systems of 100 years ago were also converted.

As a counterexample what I believe was the first electrified line in (what is now) Czechia (Tabor-Bechyne) remains for the time being at 1.5 kV despite being a branch off a 3 kV line (and despite the depot being on the other side of said line). Maybe the short section of road running over a bridge is a factor.

I think there was another one which was converted.

 

[edwin_m]

There isn't any wider plan in existence though

But is there a "narrower" plan?

 

[MarcVD]

The UK has converted its 1500 DC electrification to 25kv AC. Admittedly this was just the suburban lines out of Liverpool Street and what was left of Woodhead route after closure. The other experimental systems of 100 years ago were also converted.

Wholesale conversion of the UK's third rail systems has never really been planned other than in fantasy schemes.

There are specific cases where it makes sense, technically or financially. Not many. One example is the Belgian line from Namur to Luxembourg, initially wired at 3 kV, and currently being rewired for 25 kV. The southern part is done, the northern part is in the works and should be ready in 2 to 3 years. It's a complete reconstruction, though, not only a change of electrification scheme.

SNCF has rewired the Modane line from 3rd rail to catenary, still at 1500V, in the 70ies. I don't understand why they did not take the opportunity to go to 25 kV at the same time...

DB will eliminate the 3 kV section west of Aachen to replace it by its traditional 15 kV system next year. SBB will eliminate the 25 kV section north of Basel also. In those two cases, the goal is to eliminate life expired switchable catenary equipment, now that multi system locos make a plain line junction much cheaper and easier to operate.

 

[43096]

SNCF has rewired the Modane line from 3rd rail to catenary, still at 1500V, in the 70ies. I don't understand why they did not take the opportunity to go to 25 kV at the same time...

That may well have been down to the almost new CC6500 locos that had the necessary performance for the line being 1500V DC only. If they had thought ahead, maybe they should have been built as CC21000s?

 

[MarcVD]

I think impossible is probably a bit strong here, given that Czechia is actively converting existing lines to 25 kV.



There are of course examples where countries have more than one electrification system even on main line rail (and not only because of changing borders since electrification).

Yes I should have said Most often impossible.

A good example is France of course. Using 1500V in the south - with catenary of 600 cm2 of copper-equivalent section in some places, to support the required currents - because over there they started electrifying early, when no other solution was practically available. Military authorities banned any electrification attempt in the north and the east until way after WW2. At that time, 25 kV electrification was proven possible and SNCF started over there in a domain totally devoid of any catenary. So it made total sense...I suppose there was a similar case in eastern European countries where there is a mix of 3 and 25 kV systems, like in former Yugoslavia. Somebody cited Czechia, there is also the case of Croatia, which also converted the 3 kV lines they inherited from Italy to 25 kV. The 3/25 separation in Yugoslavia times used to be south of Zagreb...

== Doublepost prevention - post automatically merged: 4 Sep 2025 ==

That may well have been down to the almost new CC6500 locos that had the necessary performance for the line being 1500V DC only. If they had thought ahead, maybe they should have been built as CC21000s?

And also probably because it allowed them to reuse all the power line and substation equipment already in place. Not the first time SNCF would decide to do something on the cheap. Still incredibly short sighted in my opinion.

 

[etr221]

That may well have been down to the almost new CC6500 locos that had the necessary performance for the line being 1500V DC only. If they had thought ahead, maybe they should have been built as CC21000s?

I think at the time - the early 70s, before the big developments in power electronics which have changed a lot - keeping 1500v dc, with just a change from 3R to OH, was seen as the better option - what I have no idea over is how power is/was supplied to the line, which, as much as locos, may have been a consideration.

The only really large conversion that I am aware of was the Italian one, from 3.6kV 16 2/3 Hz 3-phase ac (which was their standard, from pre-WW1 to about 1930, when its limitations became apparent) to 3 kV dc. And it should be noted that when the system change was being mooted, higher voltage, higher frequency 3 phase ac was seriously considered: 3 phase was what FS's engineers of the 20s knew and loved...

 

[Bald Rick]

with catenary of 600 cm2 of copper-equivalent section

That’s a fat conductor. Must cost a fortune to electrify when it’s £50k per metre of ’wire’ !

 

[MarcVD]

That’s a fat conductor. Must cost a fortune to electrify when it’s £50k per metre of ’wire’ !

Did I really say cm2 ? My bad. mm2 of course. 4 wires, 2 contact wires in pure electrolytic copper and two stranded bronze messenger wires, about 150 mm2 copper equivalent section each.

Here is picture of a short section of contact wire used in Belgium (a bit thinner as we use 3kV) near a pen for scale .

 

[rvdborgt]

DB will eliminate the 3 kV section west of Aachen to replace it by its traditional 15 kV system next year.

Let's say: at some point in the next decade, but not next year. They've been talking about it for at least 25 years now and every time I hear about it, it has been delayed again. IIRC it's now supposed to happen in 2028.

 

[Paul AC]

I have read (and can't remember where and I have no idea if it's true) that once they've been installed a while it would be very difficult to use them as such - something about the rubber in the mounting holes?

It is presumably in any case useful not to keep supplies of two different types of sleeper.

I've travelled over 99% of the Spanish network over the past five years and can confirm that gauge-convertible sleepers are used everywhere for both new work and replacements. For clarity these are sleepers with four sets of rail fixings - a pair that suit 1435 mm gauge and a pair that suit 1668 mm gauge, these being arranged so that when changing from one gauge to the other the track centre line remains in the same place. I must admit I've wondered about the real practicalities of swapping the rails over from 1668 to 1435 mm and whether there is any degradation in the structure of the sleeper. Hopefully some tests have been done!

There are some routes in Spain where dual gauge 1668 and 1435 mm track is, and is being, laid, these have the usual three 'pads' for the rails so you have one common rail, one 1435 gauge rail and one 1668 gauge rail. The main places to see these are on the freight routes around Barcelona (which connect into the standard gauge high speed line into France) and out of Valencia towards Castello de la Plana; these will eventually be connected up to give Valencia a standard gauge route to France.

I found the electrification arrangements in Spain a bit confusing at first. The trick is to understand that it's not as simple as 3 kV dc => 1668 mm gauge, 25 kV 50 Hz => 1435 mm gauge. Yes the majority of the 'classic' broad gauge network is 3 kV, and the 'older' high speed lines are 25 kV, and where gauge changers are used the voltage is also swapped over at the same time; but it is the high speed upgrades that are being done that can confuse the unwary. As an example, as has been said, the 'classic' line to Salamanca (which has been straightened and speeded up) is broad gauge 25 kV; high speed services from Madrid to Salamanca run along the high speed line via Segovia to Medina del Campo AV, then turn off through the gauge changer there, then stay on 25 kV to Salamanca. Similarly the high speed line from Ourense to Santiago de Compostela, then the upgraded lines from there to A Coruna and Vigo, are all broad gauge 25 kV.

One problem is that there are no suitable dual voltage broad gauge suburban and medium distance multiple units yet so you still get quite a lot of diesel working in these areas, and not all the routes are electrified yet anyway.

Similarly to the gauge-convertible track, where routes are having new or upgraded electrification but in the short or medium term still need to be at 3 kV for compatibility with existing workings, the wiring is being done with 25 kV capable insulators and clearances but with the pair of contact wires needed to carry the higher dc current. This can easily be converted from 3 kV to 25 kV at a later date, subject of course to the new substations being available.