HST Electro-Diesel | Is it possible?

[Rhydgaled]

it's never going to happen

I agree. The best I hope for is that lots of mark3s are made compliant with the 2020 disabilty regs to avoid the need to order new diesel/bi-mode INTERCITY trains and that enough lines are electrified by 2035 to allow the IC125s to be replaced by purely electric stock, with a small amount of diesel loco-haulage.

 

[IanBanks-Jones]

A MK3 with a panto is basically the same as a second gen EMU (313-322), so it is basically proven.

I am aware that it isn't probable, but I'm just trying to make the point that it is as the thread asks, possible, plausible and indeed would be (I believe) feasable. It won't happen, of course. Who'd bother to re-engineer something that's already close to being 40.

I think that it's wrong to get rid of something that works well, regardless of how old it is though. Not through nostalgia (the hst's displaced my favourite class 45's), but through shrewd thriftiness.

 

[starrymarkb]

Ahh yes I'd forgotten that converting Mk3s into power cars is proven concept...

Again it's never going to happen and just about everything on this thread is an enthusiasts dream not a railway reality. In fact I'll happily eat my hat if such a train enters squadron service.

And before anyone mentions the 442s, they are based on the structure of an IE Generator car because the standard passenger Mk3 couldn't take the weight of a 4-REP traction pack. Also remember for AC you'll need a transformer which would add a few tonnes!

 

[HSTEd]

And before anyone mentions the 442s, they are based on the structure of an IE Generator car because the standard passenger Mk3 couldn't take the weight of a 4-REP traction pack. Also remember for AC you'll need a transformer which would add a few tonnes!

As I understand it, on many older EMUs, including the 442s, all the traction equipment, including transformer (if one is fitted obviously), is put into one vehicle.

If lets say we had one such vehicle in every five carraiges, that means you could make 2 EMUs from each HST set with only two new carriages.

 

[DownSouth]

This idea of converting standard passenger coaches to power cars is ridiculous. A single power car (with passenger accommodation) in a three car EMU might be a sufficient traction package for suburban service, but not for intercity service. Even if a converted trailing coach could handle the conversion to a power car without ruining the structural integrity, you would end up with the passenger accommodation of longer distance coaches being married to the motive power of a local unit, basically a unit that's useless for either application.

To get enough capacity to use the Intercity 125 coaches for what they were designed for, you would need heavier equipment taking up the full coach. At that point it would be cheaper and better to stop faffing around and just buy a new locomotive that does what it was designed to do.

Conversion of Mk3 passenger coaches to have a driving cab on one end (DTSO?) for push-pull working with locomotives would be a far more useful conversion option than trying to put traction equipment in passenger coaches.

 

[O L Leigh]

2) Depends on what you're driving, pure thyristors are absolutely useless in controlling AC motors, they can control DC motors quite nicely from an AC supply by forming part phase rectification by altering the firing angle, but this very much screws the grid.

"Thyristor Control" I'm assuming refers to the use of Gate Turn Off Thyristors in classes such as the 323, this is driving an AC motor by generating an AC waveform at varying frequencies (and pole counts) to move the motor, since an AC machine is fundamentally difference to a DC motor.

Not necessarily.

Every OLE EMU with DC traction motors since the Cl313 has used thyristor control circuits which replaced the much more simplistic and mechanical-based camshaft or tap-changers.

O L Leigh

 

[HSTEd]

If I assume the weight of a normal Mark 3 is roughly 35t, and that a new driving vehicle would weigh something on order of 50t....

Currently Chiltern Railways operate formations with one Cl67, five Mk 3s and one DVT.
This comes to a total weight of 218t for the vehicles and 90t for the locomotive, so 308t in total. A Cl67 has ~2500hp at rail horsepower, so that brings the power:weight of the formation to 8.11hp/t.

Now our multiple unit with four vehicles at 35t and one at 50t would have a weight of 190t. At the same power-to-weight ratio it would need 1540hp at-rail.

So the question is, can you build a 50t EMU vehicle with 1540 at rail horsepower, I shall conduct further research.

EDIT:
The N700 Shinkansen has 40t, 25m long vehicles with 4 traction motors generating some ~410hp each (so 1640hp per vehicle).

It appears that the traction transformers are mounted on the motored vehicles, and that its maximum axle load is still only ~10t, seeming to indicate that a vehicle wtih a maximum weight of 50t could easily be built with the power we would require to get the formation up to the p:w of a Cl67 hauled formation.
(Each 16 car set has 4 3100kg traction transformers, apparently mounted on the motored vehicles, with the two driving trailers in each formation simply being traditional)

 

[Nym]

Not necessarily.

Every OLE EMU with DC traction motors since the Cl313 has used thyristor control circuits which replaced the much more simplistic and mechanical-based camshaft or tap-changers.

O L Leigh

Ah, sorry, wasn't been entirely clear, I was refering to the GTO systems in 323s driving AC motors, Thyristors or Gate Turn Off Thyristors are very capable of driving DC motors.

Have seen many a system using thyristors with a variable firing angle to control a voltage across a DC motor, but these have all since been replaced by IGBTs (Intergrated Gate Bipolar Transistors) since the Class 92.

(If anyone wants to know what variable firing angle rectifiers using thyristors do and how they can control voltage, ask nicely and you can have a very complex explanation that will require the understanding of AC electrical systems, high ratio transformers, and power electronics.)

Not cheap, but still cheaper than full bi-mode replacements. 10-15 years of these would mean that the TOC'S and NR could assess their options properly. Re-engineering these (proven and recently re-engined) sets with (proven) technology to draw current is always going to be cheaper than starting from scratch with an unproven concept, not to mention the cost of actually building the stock itself

I really wish people would get off this bus, think of the whole life asset costs before you say something will be cheaper.

If one assumes that any assets created will be useful until the end of their life, and for Diesel LDPE stock this is effectively infinate, due to Penzance never getting wires in the foreseeable future, therefore having a life until a Diesel Hauled EMU comes into being.

Re-engineered HSTs will last 15 years tops, where as a Class 180 bodyshell with Class 390 traction systems at 10 carriages long will have a 40 year lifespan, so can cost more than twice as much, and still be worth it...

 

[ainsworth74]

Re-engineered HSTs will last 15 years tops, where as a Class 180 bodyshell with Class 390 traction systems at 10 carriages long will have a 40 year lifespan, so can cost more than twice as much, and still be worth it...

Thank you Nym! This is exactly what I've been trying to get at, HSTs are too old for this sort of modification to make anything even approaching financial sense (let alone the fact that I still don't consider the concept to be a proven one).

 

[IanBanks-Jones]

Well, If it were to happen, are we agreed that my suggestion is the only one that is anywhere near to practical? As I said, it won't happen anyway.

On a side note, has anyone thought to preserve a pair of Valenta engines for when a set gets preserved? I miss the almost painful scream

 

[Zoe]

On a side note, has anyone thought to preserve a pair of Valenta engines for when a set gets preserved? I miss the almost painful scream

http://www.125group.org.uk/index.php?name=News&catid=&topic=3 It has already been done.

 

[ainsworth74]

Well, If it were to happen, are we agreed that my suggestion is the only one that is anywhere near to practical?

Not really. If we take a 321 as a baseline for what sort of power you can fit underneath a Mk3 (and I'm not convinced it would be at all easy to turn a Mk3 trailer into a motor vehicle) then assuming that there were two you'd only be getting around 3,000hp out of the train. A 91, for example, generates up to 6,480hp. Now that's probably a tad overpowered as it was designed to hit 140mph originally but even allowing for that two motor vehicles is still going to leave us under powered compared to the other electric trains on the ECML (as well as being under powered compared to what's currently available on tap to a HST).

I'm sorry but I remain to convinced of the viability of turning Mk3 trailers into motor vehicles (certainly whilst still carrying passengers at least, stripping out the interior and turning them into power cars I could be persuaded is possible). The concept is not proven if for no other reason than (as far as I'm aware) no one has ever taken a LHCS trailer and turned it into a motorized vehicle.

 

[DownSouth]

EDIT: beaten to the point by @ainsworth74 while I was writing my post, we basically both agree.

Well, If it were to happen, are we agreed that my suggestion is the only one that is anywhere near to practical?

No, it's probably one of the most ridiculous suggestions I've ever seen. A Class 317-322 EMU is not just a Mark 3 coach with a pantograph on top and a motor underneath, the similarities would go only as far as the base design of the body shell. The thought that you could bolt on power equipment to a structure never designed to carry it and somehow end up with unaffected passenger accommodation and enough power for an intercity train is a ludicrous fantasy.

In addition, even if such a conversion was possible (which it is not), let alone practical (which it is not) it would still probably cost at least as much as buying a new locomotive off the shelf that would have triple the useful life and far better performance.

The best thing to do with Mark 3 coaches would be to keep using them as coaches, not faff around with doing anything different except perhaps adding a cab for push-pull usage if there is a shortage of separate DVTs and/or changing IC125 trailers to standard wiring if they are still to be used after the Class 43 locos are withdrawn. Keep them doing what they were designed to do until the cost of maintaining them (or upgrading them to current standards) becomes more than the cost of replacement, then run the fleet down by attrition.

 

[IanBanks-Jones]

Okay. I give in! (although those mk3's could do another fair few years with e-d power cars )

 

[Nym]

Define a fair few years?

By lifespan technically they could keep going till they rust to bits and the boogies crack, but not at 125..

 

[silvermachine]

OK

so if I understand the contributions to this thread, building an HST that could run off OHLE isn't possible because of the complexity of a transformer to convert the power to DC for the traction motors.

So.... would it be possible to have an electro diesel hst that could pick up from the 3rd rail?

Surely that would be attractive for waterloo to exeter or brighton-newcastle?

 

[Nym]

Still no...

The problem is controlling the motor, this is NOT done in the way that an EMU or Electric Loco controls its motors. So no, it is still prohibitively expensive.

There is no complexity in transforming from AC to DC, you just need a WN:W3^0.5 transformer and a 12 pole rectifier (for 3 phase) or a 1:N transformer and full bridge (for 1 phase).

The complexity lies in adding EVERYTHING that an EMU needs aside from the DC motor(s) and converting the very simple control systems currently in place to a very complex one.

 

[MattRobinson]

Surely the best solution is to build something like a class 91 but with slab ends (and driving cabs are probably unnessary as well) which sits between one power car and the rest of the set, which can listen to the signals being sent between the power cars and take instruction from that? In terms of modifications to the HST, all you need is some way of telling the power car not to listen to any instructions for the electric unit. From what is being said (and I can't comment on the control system of the HSTs), it would appear that the only complication is that the heating requires 3-phase (tickover of one power car? Or the electric unit could make three phase as stated above?) and that the electric unit would need to be able to understand this control protocol (which would be designed into it, so that's a negligible issue).

I have outlined a solution above, but TBH the question isn't 'is it possible?' (yes), but 'is it viable?' (probably not). The money that you spend on electric units is probably better spent on new stock which can be designed from the off as an electro-diesel.

 

[Rhydgaled]

The money that you spend on electric units is probably better spent on new stock which can be designed from the off as an electro-diesel.

Or better yet on OHLE and new EMUs or electric LHCS like an IC225.

 

[Nym]

Surely the best solution is to build something like a class 91 but with slab ends (and driving cabs are probably unnessary as well) which sits between one power car and the rest of the set, which can listen to the signals being sent between the power cars and take instruction from that? In terms of modifications to the HST, all you need is some way of telling the power car not to listen to any instructions for the electric unit. From what is being said (and I can't comment on the control system of the HSTs), it would appear that the only complication is that the heating requires 3-phase (tickover of one power car? Or the electric unit could make three phase as stated above?) and that the electric unit would need to be able to understand this control protocol (which would be designed into it, so that's a negligible issue).

I have outlined a solution above, but TBH the question isn't 'is it possible?' (yes), but 'is it viable?' (probably not). The money that you spend on electric units is probably better spent on new stock which can be designed from the off as an electro-diesel.

Anything is possible, but that proposal is actually WORSE than the Bi-Mode IEP!!!

 

[Mike C]

OK

so if I understand the contributions to this thread, building an HST that could run off OHLE isn't possible because of the complexity of a transformer to convert the power to DC for the traction motors.

So.... would it be possible to have an electro diesel hst that could pick up from the 3rd rail?

The transformer doesn't convert from AC to DC - that would be a rectifier (of which there are many different types). A typical modern scheme would be:

1) 25kV/50Hz AC Single phase supply
2) Transformer to step down to something in the ~1000 to 1500v range (still AC)
3) This is then fed to a rectifier (or pairs of rectifiers), thyristors, GTOs, IGBTs, etc.... The thyristors (or similar) will operate a controlled "firing angle" (google that if you want to know more - here is not the place) controlled by a computer which results in a DC link voltage - sometimes fixed, sometimes variable.
4) This link voltage is then used in many ways. Some is used via a chopper or similar to provide "hotel power" or "ETH" depending on your preferred nomenclature (basically, lights, heating, A/C, etc... for the carriages), and of course the traction systems.
5) If the train has 3 phase AC motors, the traction system will take this DC link voltage and via an inverter and variable voltage and variable frequency control (VVVF), provide what the motors need. There will also be a supply for things like motor blowers and if there is some kind of dynamic braking, it usually comes from/goes through here too.

So the transformer is only the first stage of things (or second, after the pantograph and main breaker). It is also a comparatively simple device compared to what happens later in the system, although the transformer usually is the single heaviest component on the train and requires significant cooling which usually adds an oil circuit, radiators, pumps and fans into the mix too. All of that adds weight and takes up space. This is your main problem in this fanciful HST conversion that will never happen.

The rectifiers, choppers, inverters, rheostats and control systems that are needed later in the description above all have very specific requirements in terms of the space they can be fitted into and their own cooling requirements.

In answer to your final point - there has already been a 3rd rail electro diesel - class 73 I think (someone may correct me). It was pretty gutless off the 3rd rail, but it did have that capability, and if there are any still running anywhere they must be about 40+ years old. Again, google is your friend here.

 

[Tiny Tim]

So far the subject of weight has only been briefly mentioned; An electro-diesel, whether converted from the elderly HSTs (unlikely) or the new IEP will be not only have an inconveniently weighty power unit, but will also be somewhat inefficient, carrying engines and fuel to no useful end. Isn't the simplest answer to hook a diesel onto the front when required?

 

[Hydro]

In answer to your final point - there has already been a 3rd rail electro diesel - class 73 I think (someone may correct me). It was pretty gutless off the 3rd rail, but it did have that capability, and if there are any still running anywhere they must be about 40+ years old. Again, google is your friend here.

Yes, the 73. A fair few still on the rails, as they are extremely useful little engines. 600hp engines for off juice shunting and short distance trips. Quite low powered, but very torquey and can pull well albeit slowly. They're normally used paired up for more power. Ours have done many Derby - London trips on diesel on load 4/5 adequately.

A couple are getting a pair of QSK19's each in future and having their electrical kit replaced with modern stuff to give a "super-ED" that will have broadly equal diesel and electric power (1500hp diesel, standard 1600hp electric).

 

[HSTEd]

If such an upgrade was to be undertaken it would take us a step closer to a full blown 25kV or even dual voltage ED.

Any idea when that would occur if it does take place?

 

[RobShipway]

How was it done then when the Class 91's where introduced with class 43 power cars at the end?

 

[sprinterguy]

How was it done then when the Class 91's where introduced with class 43 power cars at the end?

That had nothing to do with changing the power source for the HST power cars though. The HST power cars were fitted with the TDM multiple working system used by the class 91s (and other electric classes) to allow them to work in a push-pull format with the 91s. They were only originally intended to be used to provide train supply to the mark 3s, but due to the high risk of traction motor flashovers incurred in this mode of operation, the power cars also latterly provided traction power from their own diesel engines. The TDM equipment allowed the power application to be controlled from the class 91, and vice versa.

 

[apk55]

I am sure a transformer and variable output rectifier could could be easily made to power DC commutator motors. I would expect something more sophisticated than the phase angle controllers used on class 91 locos and class 314/5 EMUs, so that a nearly unity power and form factor is taken from the supply. (This could be done by using IGBT choppers on the output). However this probably would weigh at least 5 tons and make the power cars over weight. A possible solution would be to put them under the adjacent coach, but this would mean permanently connecting the two together. Other problems would the pantograph and may involve running a high voltage cable along the train as two on a train at high speed are not recomended. And would this be worth while doing on stock that could be almost 40 years old before there is a useful demand for bi mode operation.

However I can see a considerable demand for electro diesels locomotives particularly for freight. As more of our network gets electrified and diesel fuel price rises the economics could shift to electro diesel operation.

 

[Nym]

Still forgetting the point of LIFETIME ASSET COSTS!

It's not viable!

 

[RobShipway]

I am sure a transformer and variable output rectifier could could be easily made to power DC commutator motors. I would expect something more sophisticated than the phase angle controllers used on class 91 locos and class 314/5 EMUs, so that a nearly unity power and form factor is taken from the supply. (This could be done by using IGBT choppers on the output). However this probably would weigh at least 5 tons and make the power cars over weight. A possible solution would be to put them under the adjacent coach, but this would mean permanently connecting the two together. Other problems would the pantograph and may involve running a high voltage cable along the train as two on a train at high speed are not recomended. And would this be worth while doing on stock that could be almost 40 years old before there is a useful demand for bi mode operation.

However I can see a considerable demand for electro diesels locomotives particularly for freight. As more of our network gets electrified and diesel fuel price rises the economics could shift to electro diesel operation.

The only Electro Diesel locomtive that seems to ve viable at the moment is the Class 73, however as Network Rail have found out the diesel engine lacks a bit on powefr hence why some of them are being re - engined with an engine with higher HP outout than they have all ready.

The only other locomotive is the Eurolight that I believe DRS have ordered as per http://en.wikipedia.org/wiki/Vossloh_Eurolight, although that is mostly Diesel powered.

 

[DownSouth]

The only Electro Diesel locomtive that seems to ve viable at the moment is the Class 73, however as Network Rail have found out the diesel engine lacks a bit on powefr hence why some of them are being re - engined with an engine with higher HP outout than they have all ready.

The only other locomotive is the Eurolight that I believe DRS have ordered as per http://en.wikipedia.org/wiki/Vossloh_Eurolight, although that is mostly Diesel powered.

The Eurolight series are only diesel locomotives. I think the confusion there might come from electro-diesel being easily confused with diesel-electric, bi-mode or dual-mode are better interchangeable terms that are far less ambiguous.

I don't think that having any form of electro-diesel/bi-mode/dual-mode system within the same vehicle/set is appropriate for passenger usage in Britain. The small loading gauge, short distances, short consist lengths and high acceleration required just don't allow a successful dual-mode loco like the ALP-45DP to work in Britain. How often would it be needed anyway?

Hauling/shoving an EMU with a compatible diesel locomotive (with all the functions of the EMU's own cab worked in) would be a better move for the IEP specifications in Britain, especially since it's really not that often in real terms that it would be needed. If it was included in the same tender it wouldn't be too hard to get a good bid coming in, a joint bid from Alstom and Vossloh might be a winner. With a good integrated system for coupling/uncoupling at the last electric station, I can't see it taking more than a minute or so longer than the process of getting the gensets on a bi-mode multiple unit started up and all the on-board systems switched over.

For electric locos to be used on freight duties, I do think that including a light, low-power diesel engine for entering/leaving a yard where container gantries or hopper chutes could be an issue. I believe that Bombardier has designs ready to go if an operator wants a mini-TRAXX loco for use on British freight trains.