HST Electro-Diesel | Is it possible?

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bronzeonion

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Good evening all,

A few weeks ago me and few friends were discussing the IEP project and I thought of the idea of using the current Class 43 powercars but fitting them with transformer + pantograph and connect it up to the existing traction motors to make them an electro-diesel train. This will probably save a hell of alot of money in buying new trains completely, and will keep the timeless HST design around.

Tell me what you think.
 
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Yew

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Unfortunately one of the major flaws with this are the HST's motors. They are three phase machines, with a waveform like this

this means there are three distinct currents put through the motors. whereas OHLE uses a single phase. Now it is possible to 'make' 3 Phase from a single phase AC current, it involves some complex power circuitry.

Realistically at this point in a HST's life it is unlikely it would happen, unless some serious life extension happens

EDIT: This video explains how a 3 Phase Motor works quite well http://www.youtube.com/watch?v=N8LUOTQKXlk&feature=related
 

Zoe

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Realistically at this point in a HST's life it is unlikely it would happen, unless some serious life extension happens
I'd have thought life extension until 2035 which seems to be a possibility would count as a serious.
 

Taranis

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Unfortunately one of the major flaws with this are the HST's motors. They are three phase machines, with a waveform like this

this means there are three distinct currents put through the motors. whereas OHLE uses a single phase. Now it is possible to 'make' 3 Phase from a single phase AC current, it involves some complex power circuitry.

Realistically at this point in a HST's life it is unlikely it would happen, unless some serious life extension happens

We have been manufacturing trains with 3 phase motors powered off a single phase overhead line for years. That is not the issue.

The issue would be cramming in a large 25kV transformer, the required rectification and inverter equipment, cooling, reduced interior space due to pantograph well, VCB fitment, busbars ....etc.... Even if you could remove the guards compartment the extra weight would push the power car out of it's current RA5 rating and into the RA7 territory which will have implications.
 

bronzeonion

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@matt, My god that sounds weird, but was that using the traction motors from the actual power car?

@yew, I thought nearly all modern AC trains have 3 phase motors?
 

Yew

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I'd have thought life extension until 2035 which seems to be a possibility would count as a serious.

Unfortunately The IEP will probably push HST's off of predominantly electrified routes, and the Voyager/Meridian fleets are probably better candidates for pantographing.

Hopefully if Bi-mode is scrapped/not many ordered, HST's can work unelectrified mainlines (Ie MML and GWML currently) and some cross country routes. with voyagers and meridians doing things like Lincoln-London, where they are only using diesel for a short amount of time.
 

Zoe

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Unfortunately The IEP will probably push HST's off of predominantly electrified routes, and the Voyager/Meridian fleets are probably better candidates for pantographing.
Correct but there would still be the possibility of taking advantage of existing electrification between Paddington and Bristol/Newbury (or Reading if the train has to be stationary to change power source) and between St Pancras and Bedford although for the latter the entire route to Nottingham may well be electrified long before 2035.
 

Bald Rick

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HSTs, being of a certain age, have DC motors - which naturally has no phases. They do however have 3 phase supply through to the coaches.
 

Nym

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HSTs indeed do use a highly simplistic DC-DC gen-motor set, all the power control systems control the throttles on the primary generator, unlike voyager / mederian style DEMU systems where generators act to generate for motor drive inverters on a demand basis.

I'm pretty sure I've been through this in great detail before, it would require VERY significant modification to the Class 43 Locomotives, probably involving a full re-build of the generator and control set.
 

Yew

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Yeah, I feel quite stupid now, I seem to have mixed up the coach power with the traction power. If a mod wants to delete the posts for incorrect information feel free
 

bronzeonion

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HSTs indeed do use a highly simplistic DC-DC gen-motor set, all the power control systems control the throttles on the primary generator, unlike voyager / mederian style DEMU systems where generators act to generate for motor drive inverters on a demand basis.

I believe 91's use DC motors, HST's could use similiar control equipment?
 

Rhydgaled

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Of course, class 43s and mark3 coaches have been used as a kind-of electro-diesel before, they replaced one class 43 from some IC125 sets with a class 91 until the mark4 coaches arrived for the 91s to haul. The class 43 was intended just to provide the ETS for the (3-phase supply requiring) coaches. Basicly that's like Chiltern's generator-fitted mark3 DVTs, but they ended up using the class 43 to provide traction power too.

A bit silly to do that now though, running the diesel powerplant under the wires.
 

Yew

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I believe 91's use DC motors, HST's could use similiar control equipment?

At the risk of embarrassing myself further, a lot of the space in a 91 is dedicated to power control hoftware (the motors are mounted hanging from the body inside the bogies) there may not be enough space for the power control Hardware in a HST
 

Zoe

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At the risk of embarrassing myself further, a lot of the space in a 91 is dedicated to power control software (the motors are mounted hanging from the body inside the bogies) there may not be enough space for the power control Hardware.
How can software take up any space at all? It would be loaded onto the hardware.
 

bronzeonion

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At the risk of embarrassing myself further, a lot of the space in a 91 is dedicated to power control software (the motors are mounted hanging from the body inside the bogies) there may not be enough space for the power control Hardware.

Okay then, maybe somthing similiar but abit simpler without all the software, dont the MK3 based EMU's use thyristor control (Apart from the 319's which are chopper control)
 

asylumxl

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It's just not viable, the cost would be prohibitive and as such you'd be much better off just ordering new stock.

Unfortunately for some people, the HSTs will have to be withrdrawn eventually.
 

Nym

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I believe 91's use DC motors, HST's could use similiar control equipment?

They could, but it would still mean a total replacement of all control equipment, and the addition of significant levels of power electronics to actually implement it. Like I said, the power controller doesn't control the current or voltage onto the motor, it controls the main generator throttle!

You can use whatever control equipment you want, doesn't mean it's a good idea...

I could turn round and try to concatenate a MIMO system and explain it with classical control theory, but I won't, I'll use state-space...
 

DarloRich

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Of course, class 43s and mark3 coaches have been used as a kind-of electro-diesel before, they replaced one class 43 from some IC125 sets with a class 91 until the mark4 coaches arrived for the 91s to haul. The class 43 was intended just to provide the ETS for the (3-phase supply requiring) coaches. Basicly that's like Chiltern's generator-fitted mark3 DVTs, but they ended up using the class 43 to provide traction power too.

A bit silly to do that now though, running the diesel powerplant under the wires.

Aye - but they went like sh*t of a shovel!:lol:
 

Aictos

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Okay then, maybe somthing similiar but abit simpler without all the software, dont the MK3 based EMU's use thyristor control (Apart from the 319's which are chopper control)

Pardon me for asking but how does a thyristor control work in comparison with a chopper control?

What's the differences?
 

Nym

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Pardon me for asking but how does a thyristor control work in comparison with a chopper control?

What's the differences?

1) Thyristors and Choppers are not comparable; a chopper is a circuit (that can be formed of Thyristors might I add) where a Thyristor is a form of power electronics.

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.

Choppers tend to control DC motors as it is difficult to form a good AC waveform by using chopper circuits to control the voltage across DC motors.

(I honestly don't know what level of knowledge to aim this at)
 

starrymarkb

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Alternatively you could just accept that all good things must come to an end and the HST will be replaced by newer technology.

TBH I can't see the HST's lasting until 2035. Something will replace them before then (be it wiring, cascades, another batch of IEP (the most likely) or Son of 22x)
 

swt_passenger

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@matt, My god that sounds weird, but was that using the traction motors from the actual power car?

The Hayabusa trial was not really equivalent to an electro-diesel, as proposed for IEP, it was more like the set up you'd find in a road car.

There was no external traction supply aspect to it at all, and to make adequate room for access to all the trials electronic equipment and the battery bank it was mostly fitted into a coach that was permanently coupled to the power car for the duration of the trial.
 
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This may be simplistic, but how about converting a batch of mk3 coaches to have a pantograph and traction motors of their own, albeit operated from the HST cab with minimal alterations. Two panto cars per train (one inside each power car) would be able to do it, wouldn't they?

The HST might be old, and probably should be ready for replacement, but the simple fact is that it works.
 

ainsworth74

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but how about converting a batch of mk3 coaches to have a pantograph and traction motors of their own

Not a simple job and not a cheap one either.

I think a lot of people on this thread need to realize that the HST will, in the not too distant future, be done and as such there will almost certainly be no complex overhauls to turn them into Bi-modes or any rebuilding of Mk3s into power cars. The most likely is that some of them will get DDA conversions but that's about it.
 
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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
 

ainsworth74

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unproven concept

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.
 
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