GWML Electification

[eastwestdivide]

News on work in the Severn Tunnel.

 

http://www.bbc.co.uk/news/uk-wales-south-east-wales-36837623

 

I reckon the BBC's journalist needs to have a think about a better way of phasing the opening paragraph (my bold):

 

The Severn Tunnel has become the first place in the UK to have a special kind of electrified track put in the roof

Edited July 20, 2016 by eastwestdivide

[Zomboid]

Apart from the length and line speed I wonder how different it is from the solid overhead on Trowse swing bridge?

It's in a tunnel...

It'll be the first UK application of the F&F solid overhead, and is no doubt designed for higher speeds than the beam in Haymarket tunnel, or the Trowse bridge and the various other places similar systems are used (Thameslink? Heathrow?)

[jamie92208]

It's in a tunnel...

It'll be the first UK application of the F&F solid overhead, and is no doubt designed for higher speeds than the beam in Haymarket tunnel, or the Trowse bridge and the various other places similar systems are used (Thameslink? Heathrow?)

The Swiss have been using this type of system for some years in at least one of the big Alpine Tunnels so they probably have a rather good pool of expertise. IIRC they installed something like this in the Simplon tunnel so that they could get lorry trailer loads through as the clearances were more fixe.

 

Jamie

[david.hill64]

Taiwan also has this on the national (TRA) 3'6" gauge network. I was involved in some measurements of current collection as there were reports of excessive loss of contact in the tunnels with the new system. The trick is to get the interface between the conventional (BR Mk1 look-alike installed by BICC) and the very stiff F&F contact rail designed properly so that the pan doesn't hit the hard spot without warning. You do this by stiffening the transition over a suitable length.

[jamie92208]

Taiwan also has this on the national (TRA) 3'6" gauge network. I was involved in some measurements of current collection as there were reports of excessive loss of contact in the tunnels with the new system. The trick is to get the interface between the conventional (BR Mk1 look-alike installed by BICC) and the very stiff F&F contact rail designed properly so that the pan doesn't hit the hard spot without warning. You do this by stiffening the transition over a suitable length.

Is the stiffening done by adding some sort of blue tablet to the mix when the wire is manufactured? The mind boggles.

 

Jamie

[jamie92208]

Further to the above there are two good articles in the new Modern railways. One by Roger Ford is the second part of his article about the HOPS train and makes some very good points about the various sources of delays and also gives explanations for the 'missing' masts. The other article, by Rhodri Clark, is about the Severn Tunnel scheme and the Overhead Conductor rail System. It also explains and has a photo of the transition sections mentioned above. It isn't blue coloured but is in fact a 6 metre tapered length of the aluminium rail that get progressively more flexible as it tapers. The actual contact wire (copper) is clamped into a slot underneath the bar and then appears to just extend to be part of a normal catenary system.

 

Jamie

[The Stationmaster]

Further to the above there are two good articles in the new Modern railways. One by Roger Ford is the second part of his article about the HOPS train and makes some very good points about the various sources of delays and also gives explanations for the 'missing' masts. The other article, by Rhodri Clark, is about the Severn Tunnel scheme and the Overhead Conductor rail System. It also explains and has a photo of the transition sections mentioned above. It isn't blue coloured but is in fact a 6 metre tapered length of the aluminium rail that get progressively more flexible as it tapers. The actual contact wire (copper) is clamped into a slot underneath the bar and then appears to just extend to be part of a normal catenary system.

 

Jamie

 

I must admit to having some difficulties reconciling some of what is said in Uncle Roger's article with what can be seen out on the ground where at least three different types/sizes of pile have been used recently in the space of a couple of miles and there are stockpiles of material including several different types of pile.

 

Now that difference doesn't surprise me one bit as there are huge variations over comparatively short distances in the type of ground and subsoil the piles are being driven into and in some cases it is necessary to go a long way down to actually hit something reasonably solid on, for example, past slip sites.

 

Incidentally road-rail machines are still being used to erect catenary components and the road rail vehicles used to install contact and catenary wires are still around.

[The Stationmaster]

News report of the EIP testing:

 

http://www.gazetteandherald.co.uk/news/14626163.Electric_train_tested_at_125mph_on_Great_Western_line/

 

I like the comment  'The electrification between Reading and Didcot has been completed first ...'  At the present rate of progress, especially as isolation procedures are now required, I doubt it will be completed before September (or even the end of September?) as there is still a lot left to do including some of the most complex bits.

[The Stationmaster]

Class 800 is out to play again tonight doing several runs between Reading and Wantage Road from 00.01 onwards.  Presumably this will give the opportunity to do changeovers between diesel and electric power and vice versa but not at high speed as the average speed looks to be around the 60mph mark in the Didcot/Milton area.  Set was 21 late off depot, 16 late off Ladbroke Grove.

[St. Simon]

Class 800 is out to play again tonight doing several runs between Reading and Wantage Road from 00.01 onwards.  Presumably this will give the opportunity to do changeovers between diesel and electric power and vice versa but not at high speed as the average speed looks to be around the 60mph mark in the Didcot/Milton area.  Set was 21 late off depot, 16 late off Ladbroke Grove.

Hi,

 

Having seen a comment from one of the test engineers on the NR internal Website about the initial test run, the units were run up to speed on diesel and the Pantograph was raised on the move at speed.

 

Simon

[Zomboid]

This I assume will be pan down on the move in addition to last weeks exercises.

[Richard E]

Set returned from North Pole to Old Dalby this morning.

[The Stationmaster]

This I assume will be pan down on the move in addition to last weeks exercises.

 

I presume so - nothing wrong with lowering/raising pans at speed as it's been done on the 'mainland' for many years although it can be quite spectacular to watch sometimes.  (Easy to tell when it's happening on  a Eurostar - the aircon goes off)  I wonder if the Class 800 will have to do it at neutral sections as there could be a possibility that pans might be in two different sections on a longer train?  (Not that I have noticed any of the relevant lineside signs so maybe it won't?)

[Titan]

I presume so - nothing wrong with lowering/raising pans at speed as it's been done on the 'mainland' for many years although it can be quite spectacular to watch sometimes.  (Easy to tell when it's happening on  a Eurostar - the aircon goes off)  I wonder if the Class 800 will have to do it at neutral sections as there could be a possibility that pans might be in two different sections on a longer train?  (Not that I have noticed any of the relevant lineside signs so maybe it won't?)

The class 800 will just use one pantograph per unit, (there were two units in the video hence two pans up) so there is no issue with two interconnected pans bridging a neutral section. When the trains run in multiple the two pans furthest apart will be used. When run singly the expectation is that the rear pan will be used. The theory being that if there is a dewirement the wires should fall behind the train rather than on it. Not sure how that will work in practice.

[Zomboid]

I don't see why, there's no inter unit busline, and each unit will have its own set of magnets so will switch independently of any others in the consist. Notwithstanding that, I believe GW is using carrier wire neutral sections mostly, eliminate that risk by being longer than the trains...

As for which pan, don't they use the front one by choice on 390s? It's probably more significant to get the elbow in the more favourable position, which I have a feeling means elbow trailing, but I could have invented that.

[phil-b259]

I don't see why, there's no inter unit busline, and each unit will have its own set of magnets so will switch independently of any others in the consist. Notwithstanding that, I believe GW is using carrier wire neutral sections mostly, eliminate that risk by being longer than the trains...

As for which pan, don't they use the front one by choice on 390s? It's probably more significant to get the elbow in the more favourable position, which I have a feeling means elbow trailing, but I could have invented that.

 

As far as I am aware there are no trains in the world that pass 25KV between two self contained units - designing auto couplers capable of handling 25KV (with its flashover potential and insulation requirements) is simply too difficult, particularly as in most countries the OHLE is properly engineered to cope with multiple pantographs up at once. Its the UKs adoption of cheap and lightweight OHLE equipment that constrains things - which is why the GWML (and other NR electrification schemes) have gone for more robust equipment which allows two 5 car IEPS travelling at 140mph to both have their pantographs raised.

 

Within units its a different story. As I have highlighted before the French way back in 1980 were quite happy to have a 25KV powerline running along the roof of the passenger coaches to connect both power cars allowing a single power car to be used. In the UK the H&SE (or whoever they were back in then) vetoed the idea - forcing the APT-E to put its two power cars in the centre of the train and duplicate prevent passenger access from one half of the train to the other. The first UK train to feature a 25KV power line throughout the unit being the Pendalino.

Edited July 25, 2016 by phil-b259

[The Stationmaster]

I don't see why, there's no inter unit busline, and each unit will have its own set of magnets so will switch independently of any others in the consist. Notwithstanding that, I believe GW is using carrier wire neutral sections mostly, eliminate that risk by being longer than the trains...

As for which pan, don't they use the front one by choice on 390s? It's probably more significant to get the elbow in the more favourable position, which I have a feeling means elbow trailing, but I could have invented that.

 

Are they going to use that ancient BR idea of magnets for neutral sections - very quaint (and I haven't noticed any about as yet but that doesn't mean much as I haven't bothered to look for any).

 

Reminds me of a SPAD risk assessment meeting for St Pancras where we were getting rather concerned about the position of a neutral section not too far in rear of the exit from the 'covered way' over the GNML.  In order to sort things out we asked the project to send along an electrification expert and they sent us two.  These clowns (being very polite) were not only far from expert but kept on rabbiting on about the magnets for the neutral section - seemingly lacking any understanding at all about the electrification system that would be installed on CTRL notwithstanding their being part of the project team.  however eventually they did at least find out the site of the neutral section and it was sufficiently far in rear of the signal for it not to be a worry about Driver workload being a distraction as the signal was approached.

 

Far simpler for the Driver to have lineside signs or a balise or whatever and 'throw a switch' in the cab.  it seems to work perfectly well that way on the LGVs, and classic lines, in France judging by what I have seen on footplate rides on TGVs etc.

[Zomboid]

I don't know about magnets or otherwise. It's the only system I know of that we use in the UK to tell the train about neutral sections. Possibly not necessary with a carrier wire, not a subject I know anything about other than "we've always done it that way(with magnets)".

[Edwin_m]

Don't the magnets operate the VCBs on coupled units individually, thus keeping them powered off for the minimum time and not leaving it to the driver to judge when their last pantograph has passed through? 

[Grovenor]

Don't the magnets operate the VCBs on coupled units individually, thus keeping them powered off for the minimum time and not leaving it to the driver to judge when their last pantograph has passed through? 

Yes, I would not see it as an advance to stick up a lineside board and leave switching to the driver.

regards

[The Stationmaster]

Yes, I would not see it as an advance to stick up a lineside board and leave switching to the driver.

regards

 

Assuming the Driver can see the two boards - one to open the circuit breakers and the other to close them - then there is  o problem and it seems to work perfectly well in France (and presumably on HS1 nee CTRL).  If it has worked in France, and elsewhere on the mainland, for many years seemingly without any problems then I don't really see why it shouldn't work in Britain.  But then equally until the arrival of the Class 800 there seems to have been some sort of major hang-up in Britain (possibly down to less than robust ohle in some places?) about raising and lowering pantographs at speed for whatever reason  - including traction current arrangement changeovers.  Eurostar generally did pretty well at lowering shoes onto the conductor rail at 100mph (although they weren't always as inclined to rise as they should have been) and raising and lowerng pantographs when coming off/going onto 3rd rail (albeit with two 'incidents' over the years where pans were raised at the wrong time.

 

SNCF has no compunction whatsoever about raising and lowering pans at LGV maximum speeds and it look as Class 800 will be doing the same in Britain (although not quite at LGV speeds of course)

[96701]

Assuming the Driver can see the two boards - one to open the circuit breakers and the other to close them - then there is  o problem and it seems to work perfectly well in France (and presumably on HS1 nee CTRL).  If it has worked in France, and elsewhere on the mainland, for many years seemingly without any problems then I don't really see why it shouldn't work in Britain.  But then equally until the arrival of the Class 800 there seems to have been some sort of major hang-up in Britain (possibly down to less than robust ohle in some places?) about raising and lowering pantographs at speed for whatever reason  - including traction current arrangement changeovers.  Eurostar generally did pretty well at lowering shoes onto the conductor rail at 100mph (although they weren't always as inclined to rise as they should have been) and raising and lowerng pantographs when coming off/going onto 3rd rail (albeit with two 'incidents' over the years where pans were raised at the wrong time.

 

SNCF has no compunction whatsoever about raising and lowering pans at LGV maximum speeds and it look as Class 800 will be doing the same in Britain (although not quite at LGV speeds of course)

There is a difference between dropping the pan to allow coasting and switching the power off at neutral sections. Unless power to the train is switched off when going through a neutral section, there is a very real risk of drawing an arc across the neutral section and connecting two grid points together and to earth with rather disastrous results to the grid, never mind the OLE.

[Zomboid]

I think the drawing of an arc isn't considered such a bad thing on LGVs, where neutral sections are the carrier wire type, which aren't earthed. So any arc drawn across an overlap extinguishes when the train moves out of that section. Several overlaps are provided so it's not possible to connect different grid supplies. It seems to follow that there's no need to open the train CBs to pass through one of those, if the arc which is drawn is considered acceptable. Not knowing anything about OLE design I couldn't make a judgement on that, but I'd be surprised if "maximum plaid" through a neutral section was considered acceptable.

Conventional ceramic bead type neutral sections are different, and drawing an arc there will mean someone reconnecting wires to skyhooks. So they're protected with the magnets to automatically open and close the circuit breakers.

[Reorte]

This talk about neutral sections and circuit breakers makes me think of a connection I've never spotted before - is that why on, say, a Pendolino the aircon occasionally goes quiet for a few seconds? The lights stay on but I'm guessing battery backup there.

Edited July 26, 2016 by Reorte

[Zomboid]

Yes. If you're in the coach with the pan you can hear the bang of the circuit breaker as well. At least on a 350 you can, not certain about pendos.