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ELECTRIFICATION & ELECTRONICS


From the North West to the Great Western, electrifi cation is speeding up, with discussions ongoing on the Midland Main Line and on digging up the third rail system. Peter Dearman, Network Rail’s head of network electrifi cation, is a busy man.


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elatedly, electrifi cation has climbed the rail agenda, and following publi- cation of its Route Utilisation Strategy in 2009, Network Rail is getting stuck into the challenge.


There are scores of potential electrifi cation schemes and ‘infi ll’ proposals, with three major groups of schemes in progress or imminent across the UK – the ‘Lancashire Triangle’, the Great Western Main Line to Cardiff, and electrifi cation resulting from the Edinburgh-Glasgow Improvement Programme. Others remain on the wish list for now, including Midland Main Line elec- trifi cation north of Bedford and, in the very long term, the conversion of the third-rail network south of the Thames to overhead traction.


Peter Dearman, Network Rail’s head of electrifi cation, spoke at Railtex about the challenging timescales and innovative technology.


He explained about the shift in recent decades to autotransformer distribution, the move to taking power from the 400kv super-grid, and how feeder stations today are pumping out more than three times as much power as those just a few decades ago. He said: “The escalation in power de- livered to the railway has grown. But that brings some challenges in itself, because of course the heavier the power demand, the greater the losses.


“We’re also looking at how we make use of renewable energy resources. It’s in its in- fancy in railway traction, but our new sys- tems will employ smart-grid technology. It’s a fancy name: what does it mean?


84 | rail technology magazine Jun/Jul 11


“It means that control and protection of the traction distribution system, the switchgear and transformers that feed the system, will actually be based upon a tech- nology which allows some sophisticated control to be built into the system.


“It is not beyond the realms of possibility that the future will hold decisions being made about the building of windfarms next to the railway, on railway land. The power generated from those windfarms could be integrated into the traction network, such that they can be used when traction sys- tems demand, but we will also export pow- er back to the DNOs (distribution network operators) and out to the wider world.


“Smart-grid technology is in its infancy; we’re nowhere near ready to do that yet. But, we are putting the steps in place which will enable us to become much more able to manipulate the feeding arrangements to use renewable energy sources, and that’s quite important.”


Up in the air


Dearman is also clear that ‘something must be done’ about the third rail electrifi ed sys- tem south of the Thames.


He said: “It is at the limit of its capabili- ties, in my opinion. The 750v system can- not sustain higher speeds than about 80- 90mph. Some of it runs at 100mph, but it doesn’t run very well. It doesn’t have the capability to deliver power suffi cient for the density of services that are operating south of the Thames. Some of those services are speed restricted as a result of that limita- tion. It’s not a matter simply of dumping


more and more power supply to the system to deal with that, because the conductor rail has an effective limitation on its abil- ity to distribute the energy, and in fact at high-load times, the traction system itself is running at about 25% loss.


“We are currently developing the propos- als to convert that system to an overhead traction network. That is a non-trivial de- cision! There is 4,000km of railway with conductor rails; over the course of the past 70 years, much of the infrastructure has been built with the thinking that we can get as close to the roof as possible, in terms of bridges and decks, which of course you can with a conductor rail. So, that conversion programme won’t happen overnight. But my belief is that – probably when I’m dead and gone – the whole system will be con- verted to an AC overhead traction system.”


Timeframe


But as well as preparing the network for technological advancements and such long-term ideas, Dearman must also deal with the upcoming electrifi cation projects. He said the 2017 completion date for Great Western electrifi cation “sounds a long time away”, but added: “You have to bear in mind that what we actually have to do is to get out on the GWML, then to erect something like 23,000 steel masts, we’ve got about 800km of wiring and registra- tion assemblies, and this is not just on the plain line, but through all of the junctions and stations and everything, and we’ve got to do that largely without disrupting the railway that’s in operation today. Doing all that, when the possession windows at night are only six hours, is a challenge.


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