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Author Topic: Great Western Main Line electrification - ongoing discussion  (Read 153875 times)
grahame
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« Reply #60 on: September 28, 2017, 08:57:44 pm »

This IET event sounds highly relevant - https://communities.theiet.org/communities/events/item/259/266/18217

Details at http://www.theiet.org/events/local/250178.cfm

Open to all (not just IET members) and free to attend, but need to register by September 21st.
 

Thank you for that - a fascinating afternoon.  I learned an enormous amount about electrification ... and will never look at that catenary or pantograph in quite the same way again.


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John R
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« Reply #61 on: September 28, 2017, 09:31:05 pm »

Did they explain why there is so much steelwork compared with previous schemes (and indeed the pictures I've seen of the current Scottish electrification projects appear more like the older installations too.)
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grahame
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« Reply #62 on: September 28, 2017, 09:48:40 pm »

Did they explain why there is so much steelwork compared with previous schemes (and indeed the pictures I've seen of the current Scottish electrification projects appear more like the older installations too.)

Higher tensions and pressures for faster running ... need for stuff that lasts longer and needs less maintenance because we're headed for the 24 x 7 railway.  Also quicker maintenance by replacing components rather than tailoring each piece.  But the folks today are on the maintenance training rather than design side; 100 OHLE and associated engineers to be trained. Not only GWR mainline, but Crossrail too - which is the bigger one for maintenance because of the huge number of extra pantograph passes over the wire.
« Last Edit: September 28, 2017, 09:55:23 pm by grahame » Logged

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Thatcham Crossing
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« Reply #63 on: September 28, 2017, 10:47:54 pm »

Appears to be work ongoing on the B&H this week, with more infrastructure erection between Southcote Jct and Theale, and also between Ufton Nervet and Aldermaston.
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John R
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« Reply #64 on: September 28, 2017, 10:50:08 pm »

Thanks for the explanation.

Though I expect that faster running is 140mph specified that we will never see, just like the Pendolinos and Class 91s will never achieve their design potential in service.
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Timmer
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« Reply #65 on: October 06, 2017, 07:49:25 am »

In view of the importance of highlighting the total closure of Reading station next weekend, I have split this topic which can be found on this board by clicking the link below:

Total Weekend Closure of Reading 14-15 October
http://www.firstgreatwestern.info/coffeeshop/index.php?topic=18827.0
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Electric train
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« Reply #66 on: October 06, 2017, 08:03:49 pm »


Though I expect that faster running is 140mph specified that we will never see, just like the Pendolinos and Class 91s will never achieve their design potential in service.

The current plan is to remain at 125, although there is an aspiration to all a higher permissible speed once full ETCS is in place. 

The main driver for the GW scheme was lessons learnt from the Mk3 equipment on the ECML and the modified Mk1 on the WCML both have inherent failure modes.   The support steel and piles used on the GW are heavier that perhaps needed and I know this is one aspect the designers are looking at to see if something can be done but still meet the requirement DfT place on the scheme; however if you look at the GW OLE system there is generally one insulator per structure that supports both the contact wire and catenary where as the Mk3 had at least 2.  This reduces the likelihood of insulator failure by about 50% also the wire run design is elegant in its simplicity.

The other thing the GW scheme is using is carrier wire neutral sections similar to the ones used on HS1, instead of the NR norm is beaded neutral sections, the first of these carrier wire neutral sections is due to be commissioned at Maidenhead, the neutral sections are located West of country end of the Silco Drive sidings
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TonyK
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« Reply #67 on: October 06, 2017, 10:51:07 pm »

Thanks II. There is clearly more to the GWR electrification than meets the eye of the layman. This is a new design using engineering techniques developed because of the problems on earlier projects. There's no better way than learning from somebody else's mistakes, although headline cost probably played a large part in choosing the Mk1 and Mk3 systems.

Do it cheap, do it twice.
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grahame
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« Reply #68 on: October 08, 2017, 07:21:48 pm »

A couple of contrasting pictures from recent days

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dviner
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« Reply #69 on: October 09, 2017, 06:44:32 pm »

I like the way that the Series 1 arm (the left one of Grahame's pictures) holds both the support and contact wires - much simpler than the other example.



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« Reply #70 on: October 09, 2017, 09:09:01 pm »

I like the way that the Series 1 arm (the left one of Grahame's pictures) holds both the support and contact wires - much simpler than the other example.

The one on the right is Mk3 but it like its either in a station or a depot, normally the insulators on Mk3 and Mk1 are mounted on the structure (mast) end of the cantilevers, this was due to the weight of the porcelain insulators used.  The reason I think the right hand photo is a station area this arrangement is used to ensure live parts are as far away from the public as possible.

The image on the left as I mentioned in a post earlier the GW OLE design is exigent in its simplicity, its just the structures used to support it are a tad OTT.  In the left photo the conductor above structure boom is the ATF (Auto transformer Feeder).  There is 50kV between the ATF and the contact wire (its a 25 - 0 - 25kV system)
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onthecushions
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« Reply #71 on: October 09, 2017, 09:56:11 pm »


A good point is made by ET on the elegance of the support arm arrangement. I hope that the ceramic insulators are up to the considerable bending moment imposed on them.

I cannot understand the mast and beam design - the lengths seem random. Some masts can support the feeder, some need extensions which are anything but standard and some require posts on the portal. This must be a nightmare for the teams that have to invent a new solution each 50m, defying efficient serial installation. The BR Mark 1 portals with their diagonal lattice (often appearing on the Series 2 system) look much neater and must be potentially  stronger than the boxy, rectangular bracing of Series 1 with its monolithic masts/stanchions and clamps.

The Enhancements Delivery Plan document of September does however read a little more optimistically about electrification, if you move the CPx's along, with Stalybridge still in and Midland Bi-mode operation spoken as from "Market Harborough/Kettering", i.e over the Desborough hump.

OTC


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« Reply #72 on: October 10, 2017, 12:23:41 pm »


The Enhancements Delivery Plan document of September does however read a little more optimistically about electrification, if you move the CPx's along, with Stalybridge still in and Midland Bi-mode operation spoken as from "Market Harborough/Kettering", i.e over the Desborough hump.

OTC


AIUI, Stalybridge has to be in, as it is where the new grid connection is, unless someone wants to invest in a very long extension cable ;-)
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onthecushions
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« Reply #73 on: October 10, 2017, 01:34:01 pm »

AIUI, Stalybridge has to be in, as it is where the new grid connection is, unless someone wants to invest in a very long extension cable ;-)

I think the "extension lead" is needed anyway as the main supply point at the trackside is to be at Ordsall Lane in the centre of Manchester. Otherwise a suicidal pidgeon from Ashton can take out most of Manchester's services. (We'll have similar "leads" from Melksham and Bramley.) The actual GSP is, I believe the switching/transformer compound of the former Heyrod power station. This strongly favours continuing the wires Eastwards to Yorkshire.  It seems that this also supplies most of Manchester's commercial and residential consumers. No pidgeons, please.

The MML situation is also interesting in that the power supply for the Corby wiring is to be taken from a new compound at Braybrooke, Market Harborough, where the 400kV line crosses, suggesting that MH may be the termination. This would also certainly feed to Leicester. The other two MML feeds are proposed for Kegworth (i.e Ratcliffe Power Station site) and Hasland (from Chesterfield NG Substation). I suspect that the key to future electrification may lie in the ease of connection to the juice. The Braybrooke GSP will be the most expensive, hence the one to get installed quick!

As always I sit at ET's feet in these matters.

OTC
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TonyK
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« Reply #74 on: October 10, 2017, 09:27:27 pm »

AIUI, Stalybridge has to be in, as it is where the new grid connection is, unless someone wants to invest in a very long extension cable ;-)

I think the "extension lead" is needed anyway as the main supply point at the trackside is to be at Ordsall Lane in the centre of Manchester. Otherwise a suicidal pidgeon from Ashton can take out most of Manchester's services. (We'll have similar "leads" from Melksham and Bramley.) The actual GSP is, I believe the switching/transformer compound of the former Heyrod power station. This strongly favours continuing the wires Eastwards to Yorkshire.  It seems that this also supplies most of Manchester's commercial and residential consumers. No pidgeons, please.

The MML situation is also interesting in that the power supply for the Corby wiring is to be taken from a new compound at Braybrooke, Market Harborough, where the 400kV line crosses, suggesting that MH may be the termination. This would also certainly feed to Leicester. The other two MML feeds are proposed for Kegworth (i.e Ratcliffe Power Station site) and Hasland (from Chesterfield NG Substation). I suspect that the key to future electrification may lie in the ease of connection to the juice. The Braybrooke GSP will be the most expensive, hence the one to get installed quick!

As always I sit at ET's feet in these matters.

OTC

We have a National Grid, in the process of upgrade if the money doesn't run out. That gives us the country-wide equivalent of a ring main, spreading the feed from power stations and the demand from consumers to even out the blips. That should give us the ability to electrify practically any route, especially as you see pylons following most main rail lines. The bigger problem will be that only around 40% of the country's energy use is by electricity. Transport - including rail - remains predominantly powered by fossil fuels, as are home heating, cooking, and industry.

ET and II will agree that the eventual solution will be all transport powered by electricity. To achieve that, we need a lot more capacity for the reliable and predictable generation of electricity. Hooking it up to the mains is a minor issue compared to that (Melksham is particularly favoured in this respect).

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No pidgeons, please.

That nearly got me saying I would chase them away in my "Magimix belong Jesus".
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