Great Western Coffee Shop

Indeed - where's all the electricity going to come from?  Coal-burning power stations closing, Hinckley Point C still a way off, no sign of Severn Barrage being built...

(Re-reads original post)
...
oops.  My mistake.  As you were.

These are truly boom times for, er, booms!

"Boom, boom."  As Basil would say...

As an electrification engineer the last thing I want is booms ...........................

They are usually preceded by a big blue flash  ;D

Would he be called Gordon (as in Flash Gordon)  :D :-[





Edit note: Quote marks fixed, for clarity. CfN.

A few bright sparks have posted some rather shocking puns there.  ::)

Why do these threads always DCend into puns ?

Watt d'say?

All this AC/DC talk...don't the wires swing both ways .....???

Are you talking about bi-modes?

I am at least developing a resistance to these puns.

Resistance is futile ! (unless more than one ohm)

"Hells Bells", that's enough!!!  or we'll all be on the Highway to Hell

I don't have the capacity to take anymore of this as you have all LED me down the garden path.  I'll get my hat and coat and go ohm now...... ::) :P

Shocking positively Shocking .

Don't be so negative.

Those responsible for this battery of puns need to be charged.

Anyone would think that we had no Ohm's to go to !....

Resistance is futile.

That reminds me of a case where some bloke was arrested for stealing a battery and a firework. The police didn't know whether to charge him or let him off.

It is with some reluctance that I join this discussion.   Some of you must have nothing better to do at ohm, you contribute with such frequency...   ;D

Paul

The bouncer wouldn't let me into the club because I wasn't wearing a tie. None of my friends had a spare, and the nearest we found was a pair of jump leads. I tied them in a Windsor and went back to the door, where the bouncer looked me up and down suspiciously.
"Alright," he said at last. "You can go in. But don't start anything, okay?"

I think this is a natural progression from 'GWR electrification is a joke !'

I notice that Nederlandse Spoorwegen (Dutch Railways) is now running 100% on wind power - according to the Guardian (https://www.theguardian.com/world/2017/jan/10/dutch-trains-100-percent-wind-powered-ns?CMP=twt_gu)

Aside: Don't they have any Diesel Trains?  Or do they make that with wind power. 

There are some DMUs in the Netherlands but these are mainly (possibly entirely now from the above claim) operated by others such as Arriva and Veolia. Freight companies also operate diesels.

That's just accounting really. More interesting was the idea of connecting solar farms directly to rail:
https://www.theguardian.com/environment/2017/jan/10/solar-panel-research-power-trains-imperial-college-london-1010
They claim:
So trains don't run at night?

Isn't it rather: "doesn't the travel peak ever happen in darkness?" Answer yes, even in London, in the winter.

I suppose he means in seasonal terms; there is more travel in summer. But that's rather a vague sort of "peak".

I was assuming he meant there was more demand during the day.

That is a bit of typical windmill spin (beg pardon). Rail company buys n units of power from "green" company, which produces around n units of power from sub-leased wind turbines intermittently and unreliably, and pumps it into the national grid. Along with gas fired, coal-fired, oil-fired or nuclear powered generators. So rail company can claim green credentials. We had similar with the "poo-powered" bus in Bristol "number 2 route, obviously". Bus is converted to run on natural gas. Bus company makes contract for gas with company that makes gas from sewage. Said gas goes into national supply, from which bus is fuelled, possibly with actual molecules imported from Qatar, but it makes for clever advertising with lots of toilet puns. It has since gone down the pan.
The cleverest was a French bottler of sparkling water that boasted about its product's "natural" gaseousness. As it was tricky to transport fizzy water over long distances, the natural gas was discharged to the atmosphere, then the resulting still water, after a long tanker trip, was re-fizzed when being bottled using gas recovered from the same atmosphere. Which makes it naturally sparkling. I believe they were told this was not on, eventually.

Really? Really?

Theoretically Network Rail is 100% nuclear or renewables .............. at least that is the contract NR has with its energy supplier  ;D but it is difficult to filter nuclear derived electrons from coal or gas derived electrons when the come streaming out of the end of a high "pressure" cable  ;D ;D 

But if people only bought from suppliers of wind and nuclear in the end there would only be wind and nuclear suppliers - though the grid would then have to buy in organisations with systems (batteries or pumped storage?) to balance the load.

About 1GW of electricity most of the time from the Netherlands comes through the BritNed interconnector into the National Grid representing a wind power surplus. Although through the last couple of months due to some power station outages in France, a similar amount has unusually been routed back there. Normally the output roughly equivalent to 2 of the 6 reactors at Gravalines is b(r)ought across the channel.

Really, really. Wind is, as we speak on this blustery day, providing some 13.1% of our electricity (coal 15.5%, nuclear 15.7%, and gas 44.6%, all according to Gridwatch (http://www.gridwatch.templar.co.uk/). Over the past few days, wind has provided under 2% at times.

And as much as 20% at times yesterday, not including the Dutch import. Not much solar though at this time of the year ...

For a moment I was starting to think FT, N stood for 'For Trump, Now!'

I presume when you say 'unreliable' you are referring to the wind, not the turbines; the turbines are anything but unreliable.

With the efforts now going into Enhanced Frequency Response (http://media.nationalgrid.com/press-releases/uk-press-releases/corporate-news/national-grid-brings-forward-new-technology-with-enhanced-frequency-response-contracts/), plus the massive increase in battery production (http://spectrum.ieee.org/transportation/advanced-cars/2017-is-the-makeorbreak-year-for-teslas-gigafactory) that will shortly come online, large capacity grid energy storage starts to look like a serious player. Which means that highly-efficient WTs can work all the time there's a wind, either powering the grid or charging batteries. 

You can tell us apart by our hairstyles. And those Russian hotel pictures - those could have been anyone's buttocks, and anyway I only met Ljudmila the once.


Indeed, the wind is unreliable, and sometimes so absent that wind turbines become net consumers of electricity. Developing batteries to store excess power for its own sake, so other than in electric vehicles, is at present a nonsensical idea. Even when wind is providing its highest proportion of the electricity mix, it never produces a surplus. The practical effect is that we can turn down the gas on the CCGT stations. When we have a base load from some non-fossil source to cover the minimum electricity we use, then wind may tip the balance into surplus, but by then we will hopefully be running much more of our rail fleet on electricity, and will have a lot more electric cars. Of course, that will increase the amount of electricity consumed, changing the equation yet again.

Meantime, coal has made a sudden comeback, rising from almost zero not long ago to 17% today - someone has turned a few stations back on! They take time to get to working speed, and are generally run flat-out if possible. If we were to store excess power, it would be better to do that at coal stations rather than either dumping the suddenly unwanted hot water in the cooling towers or running the turbines without generating power. That coal is back tells me that we certainly don't have the generating capacity we need now, without considering electrifying public and private transport on a bigger scale.

Now, if trains can be run on solar power, and you need somewhere to put the panels, why not on the train roof? It is connected to the power supply, and power is already returned to the system in regenerative braking? No train would ever be able to power itself, not even on the sunniest day, but on the basis that "every little helps" could it work?

FTR, FT, N! awaits the outcome of the proposal to build a tidal lagoon somewhere near Swansea with interest. So long as this doesn't solve one problem but cause two more, it could be a goer on a national scale. We know with remarkable accuracy what the tide will be doing there at any given time within the next 100 years, and the energy density of water is higher than that of wind.

The problem with wind, solar and the interconnectors into Europe is they lack inertia that a steam (or hydro) driven turbine genset has, NGC has some problem with sync, power factor and fault recovery times on the supper grid 

Here is a picture of a 'supper grid' (also known as a 'toast rack'):

(http://www.bristolpost.co.uk/images/localworld/ugc-images/276268/Article/images/28210050/11425172.jpg)

CfN  ;) :D ;D

Funnily enough, I had toast for my supper,  with cheese. It was super!

Looks like it's seen better days - isn't there a bit missing?

The key here are the faces ;) :D ;D CfN has put. It is the coffee shop equivalent of an in joke.

I think one of the media outlets kept using this broken TPWS grid to illustrate pretty much any train related article  :D

Yes, it can be found in several places in this (currently) 33 page long thread :D http://www.firstgreatwestern.info/coffeeshop/index.php?topic=11558.0

....and after nearly four years it still hasn't been repaired... ::) :P

Nuclear power stations in the UK are normally sited close to the sea or in one case to a large lake to provide a lot of cooling water.  The one by the lake did end up heating up the lake more than was desired sometimes.

I know they have inland nuclear stations on the contents I assume this is possible because they have bigger rivers.

Nuclear has nothing to do with it, though size (power) does. All thermal power stations need somewhere to reject heat at as low a temperature as possible. And all the big ones on rivers will, in summer, run up against the limit placed on them for the maximum downstream river temperature. So they have to dump some power somewhere else, or turn the wick down. Many will have cooling towers to help out at such times, though usually too small to take the full power. I think some air cooling may be used too.

Fortunately peak demand is lower in summer - though as you go south (or the equivalent effect is produced by global warming), and as we install more air conditioning, this may cease to be true.

You don't have to go south; electricity demand in Poland (which does have hotter summers than Britain) is highest in summer, and it's mainly down to air conditioning. Also because electricity is very rarely used for heating there (it's mainly coal or oil).

I got scared by a little spark when disconnecting the negative terminal on a car battery earlier today. Classic banging of head on bonnet underside and dropped spanner through engine bay.

So I think I'll stay well away from 25kV AC. Kudos to those who work with it day in, day out.

A word to the wise Allways disconnect the Earth Lead first  and Reconnect it Last
Negative - terminal = Earth  ;)

Yes, well aware it's negative first off, last on, on nearly all cars. As I was doing. Small sparks are to be expected apparently. I just wasn't expecting.

I was working on electrics - the aerial base needed replacing - requiring removal of courtesy light assembly. So not fully removing battery.

I learned my lesson with a 415v 3 phase supply - switchgear for generator failed and when the external supply came back the generator was still trying to maintain the juice.   They didn't agree!

When I was on work experience at a computer maintenance company, we were stripping down some monitors (old CRT types) and the chap explaining it to me was discharging the tube by shoving a screwdriver into some part of it, holding another on the ground and touching the two together. Just as I was about to do it, he said to me "if you do it wrong, it won't be the shock you remember, it will be the smell of the burning flesh" .... not what I wanted to hear! (and now I feel really old thinking back to that!).

There's still plenty of positive earth cars knocking about....granted not very common now but nevertheless not unheard of

Another top tip when working on car (or any similar) battery terminals is to always remove any rings and/or metal watch straps etc while working. 

While you're being extremely careful with any tools that you are using, rings and watch straps are just the sort of things that accidentally make good conductors, and they'll get pretty warm while doing so...

Paul

And anyone carrying an unwrapped 9V battery and a 10p coin in his pocket is unlikely to do it twice. I certainly won't!

I've also discovered that many modern cars actually have live terminals on alternators with engine stopped. I discovered this from a significant flurry of sparks from a (subsequently dropped) spanner as I was undoing the terminal nuts...!!

Another top tip is to connect a battery charger or external starter pack before turning on at the wall (same also goes for jump leads - connect up before starting the 'donor' vehicle) - plenty people have been badly burnt (acid) by causing batteries to explode from the sparks generated by connecting an energised charger or starter pack.

As a teen, there were some who put both terminals of a 9v battery on their tongue....

And the starter motor, and anything else that is attached to the electrical system and has exposed terminals.

At the time when NatWest/RBS had their major batch payments problem (the one that went on for weeks not the other hiccups) there were some allegations that due to outsourcing, the knowledge previously built up had drained away (not everything is documented of course). I suppose there is a real distinction between skill and knowledge (i.e. I could theoretically drive in central london and get you where you want using a GPS/map, but having the knowledge in your head is superior IMO).

And to do that it must have a steady (if slow) programme of work.  Rushed programmes to meet politicians grandiose and plans announced to win votes will never do that. 

That will allow work to be properly phased with other work (e.g. Bristol East Junction and Temple Meads Works) to minimise electrification costs. 


I hope your reference to Oxford's unaffordable new station only relates to iconic buildings, rather than the much needed capacity improvements.


Even better complete the electrification of some routes and cascade the existing bi-modes that can then be replaced by electric only trains. 

Has anyone suggested converting half of the class 43 fleet primary electric power (essentially their diesel engines are used to make electricity anyway, right?) and running trains with one electric and one diesel power car?  There' an awful lot of diesel mileage that doesn't need to be on both east and west coasts, some of it coming up cross country.

Network Rail, and of course DfT/HMG, have to commit to a 25 year programme to fully electrify all rail track throughout Britain and N Ireland.

This is not a simple or cheap option, but a proper long term commitment will allow training and equipment to used efficiently, rather than on very expensive short term projects which do not make full use of these.

I wouldn't say 'all track' within 25 years, but I would agree that a long term commitment is needed to a fixed budget every year to be spent on electrification.

Yes over 30 years ago!!!!  The ECML services to Aberdeen from London KX were planned to be electric loco one end class 43 the other, this is why some of the class 43 had nose surgery to fit buffers and screw couplings.

Class 43 were designed to operate in tandem this was the design choice in the early 1970's to keep the mass of the traction power unit down especially the un-sprung mass of the power bogies, the track engineers concerns of the effects on track geometry at increased speeds (125) where there was a high cant, also the un-sprung mass effects the ballast formation on plain line.

The Bo-Bo choice over Co-Co (class 47 50 55 etc) at the time also limited the power rating of the traction motors, class 43 have dc traction motors the revolution being in class 43 the use of a 3 phase alternator and SCR (silicone controlled rectifier)

Not quite. The hybrid sets were put into service to enable full electric running to Leeds early, as the Mk 4 sets were not available.  The original plan was that the Class 43 would run as a DVT, but engineers quickly found that having the loco idle was far from ideal, so they were soon run under full power, resulting in a rather nippy combination of >6,000 hp.

(Source:  Modern Railways Special on East Coast Electrification by Colin Boocock, 1991)   

Agree, memory fade on my part  ;D 

I believe the intention was to later deploy them onto the Aberdeen's but that never came about for the reason you gave, so the standard HST combo remains

I think you mean >8,000hp; according to Wikipedia a class 91 has 6,480 hp by itself without an IC125 power car helping.

I don't think I've ever read about sending the 91+IC125 combos to Aberdeen, it was only ever a stop-gap while waiting for the mark 4s as far as I know (although I think some interesting things were done with IC225s and diesel locos on some of the beyond-wires extensions of Leeds services).

Yep, thanks for the correction regarding total horsepower.

One possible hybrid might be developed through re-use of the ECML Mark 4 + class 91 sets with a class 67 (9 of which are stored out of use, it seems) instead of the DVT.

The 125mph class 67 has a 3200HP engine that delivers 1860kW to rail, about 1.5 HST power cars.

The 91 + HST power car could reach 120mph in 170 seconds! (Semmens).

Paddington - Minehead special anyone?

OTC

The 67s were so unreliable @ Chiltern that they got 68s in.

I've read that fuel economy had something to do with that change; whether its true or not I don't know. Either way, it hasn't stopped ATW using 67s (not yet at any rate), perhaps due to lease costs??

What sort of service intensity would require switching from the 'classic' mode to that which uses the ATF wire?

I believe the original Crossrail plan was to run classic 25kV mode initially with the ATF being commissioned before the full service started, this is quite normal to start in classic and then commission the ATF.

It is difficult to for me to say at what point of service intensity the ATF is an absolute as cannot remember the capacity of OOC FS also factors like the OLE wire sizes, characteristics of all of the units in use and the number of trains.  You get to a point where the volt drop effects the performance of the trains and you run the risk of track feeder circuit breakers tripping, although the Route Electrification Engineer should never let Ops get it to that stage

It is possible even when the system is in full operation for it to run in degraded mode (ie classic) that comes with performance risks which the Route should have for the likely scenarios

I think that the physical limitations are the on-load voltage (this must not drop too much on motoring) and the voltage on the return rail. The on-load volts depend on transformer size (modern ones are typically 2x40kVA, rather than formerly 2x10kVA), line impedance (i.e how far from the FS/GSP you are) and motor demand. These are not probably an issue. Track volts is however, as safety touch voltage is assessed as 50V and we don't like to get near that.
A high return current requires the track volts to rise (steel rails aren't dreadfully good conductors) in order to drive the current to earth. This is why the BT (booster transformer) system is used, to suck current from the rails into a return conductor wire, keeping track volts lower. Even better is the AT which both drains current from the rails (lowering volts) and also tops up the overhead line.
These patterns can be modelled by computer using actual timetables so that track volts may be known in advance.
I believe some lightly trafficked lines in the ER (say 2 4-car EMU's per hour) work on the classic system permanently. Our 80x's, 387's etc in full cry will certainly need the AT system if our orangemen's hi-vis jackets aren't to sparkle and glow.

As always, I would defer to ET's definitive knowledge in this area.

OTC

Think you meant 40MVA for modern 400kV derived ATFS, the classic 132kv derived transformers the smallest is 10MVA and the largest is 26MVA, BSEN50122 allows for a max of 60V however as the running rails are bonded to an earthwire every 400 metres and the earthwire is attached to a metal structure banged into the ground every 50 metres the rail to earth voltage is not too much of an issue except under fault conditions when a much higher rail to earth touch potential is allowed

Quite right. 10kVA would just about drive a bathroom shower.

It's a downside to (slips in using) the metric SI system. You expect your order to come on a low loader and a jiffy bag arrives by post...

Please be patient with the occasional techie post. They do mean something and we have some really valuable insiders here.

Chastened,

OTC

There is no problem using the SI system if you use it and not try and translate from some other older system all the time.  If anyone had tried to make me do engineering design in anything else I think I would have gone mad. 

The Americans try and use several systems and they have made some very expensive mistakes as a result (remember the hubble space telescope that would not focus because the lens had been made wrongly?)

I recently tried to look at a design method in an American text book. 

Values in the text were quoted in metric, but quoted in imperial units afterwards in brackets. Equations were then all shown in imperial units (they were not dimensionless).  Fluid flow measurements were quoted in gallons per hour and air flow in cubic feet per second! And we were trying to move two phase flow! The whole thing just made my head hurt reading it.  What chance there was of anyone actually coming out with a correct calculation was quite beyond me.

When I started my career the construction industry had been officially working in metric units for 8 years. All our drawings were metric.  The only problem was that our aged workforce could not or would not take instructions in metric.  They claimed not to be able to understand the drawings.  So I got very used to reading a drawing that said the height of the kerbface should be 125mm and telling a 60 year old craftsman to build a 5" kerbface. Some would say the local authority should have been more forcefull in getting its workers to change, but it was only mildly annoying and far better than the private contractor I had who, although he worked in metric, did not even know what a mitre joint was! 

Those who want a post Brexit Britain to go back to imperial units should be firmly told that UK will only succeed if we have a modern industry and it cannot become a museum.


I am happy to be patient.  I can be techie in my own field but I am not an electrical engineer, but it still interests me.

Sorry to correct, it was one of the Mars spacecraft that missed due to mismatch of units. The Hubble Space Telescope suffered spherical aberration due to mis-measurement of a calibration rod used in testing the optical figure of the surface of the primary mirror. The mis-measurement was nothing to do with the units in use but rather due to a defect on the end of the rod. The telescope could focus fine, it was just that there was a different focus for the various parts of the mirror surface!

Thank you facts are important

what a refreshingly old-fashioned attitude

But 'alternative facts' can be wonderfully useful when real ones are annoying.  ;D

Don't forget the Gimli Glider (https://www.damninteresting.com/the-gimli-glider/). A Boeing 767 had a dicky fuel measuring system, so the pilot asked the engineers to dip the tanks. That gave a result in litres, which they converted to kilograms - but using the multiplier for pounds rather than kilograms. This was the first aircraft they had used that measured things in metric. It ended reasonably happily.


Physics was my best O-Level result, which doesn't make me a scientist! While I appreciate that some of the discussion means nothing to you, and very little to me, I tend to feel that this is the right place for it in the context of the whole electrification project. I have only just got to grips (possibly!) with the Autotransformer concept thanks to patient explanation from our in-house experts and a lot of off-site research.

This forum, IMHO, benefits greatly from the contributions by some of the more learned members, be they couched in technical language or layman's terms. I don't think we will ever get to the point of page after page of swapped equations. Perhaps we could ask for a simple explanation as to what is being explained?

I can still recall the main equations for electricity, which is enough to figure out what fuse an appliance needs, and some of the general principles - an experiment in the laboratory at school using the 12V supply and some basic stuff was enough to convince me that the resistance of a length of wire varied with the cross-sectional area, and how crucial is that on a railway at 25KV?

On metric measurements generally, I was part of the first year at my school to regard the acceleration due to gravity as 9.81 ms^-2 rather than 32 feet per second per second. When you add motion to mass, it is so much easier when everything is based on units that divide by 10, rather than 12, 14, 28, 3, 20, 1760, or whatever. I am occasionally weighed by nurses in hospital. They do it in kilograms, then ask if I want to know the depressing answer in stones and ponds. They are somewhat flummoxed when a man of my age says it would mean absolutely nothing, but they trot it out anyway. How do you work out body mass index in Imperial? Or did we not do that before metrification?

Please bear with the occasional foray into academe, but stick with us chuffed. Your contributions are highly valued too!

How many stones does your pond have in it are you perhaps building a water feature ?.

You may have hit on something there, with regard to my own mental state: Back in the late seventies when I did Mech Eng at Bristol Poly, we had a lecturer who eschewed SI units in favour of the gravitational fps system, based on the slug (https://en.wikipedia.org/wiki/Slug_(mass)). The consequence of this was that we spent our time arguing with him about the relative merits of units systems instead of learning about therodynamics. Turned out that this argument was rehearsed afresh every year, but somehow he kept his job.

There's a lot of exaggeration about teaching of the metric system, my late mother (b 1929) insisted she was taught metric weights and measures in the 1930s, and she disagreed completely with the argument that older people just couldn't deal with it at all.

I did secondary school science in the CGS system, rather than the MKS system, during the period up until about '71.

Paul

My ounce sometimes drinks from it. I see now why the forged banknotes I printed were quickly spotted. I shall spell my next batch of man-made fivers properly.

(Actually, it was a typo)

This apparently new topic has been created in response to some requests from Coffee Shop forum members, who were understandably concerned that our 'specific discussion' of the electrification of the Great Western Main Line was becoming a bit confused with the rather more technical aspects of railway electrification in general.

I have therefore split off many previous posts and moved them here, into this more general - but often very technical! - discussion topic.

I hope this helps.  CfN.  :)

Many thanks for doing that ... fearsome ... job of splitting the topics.   Very worthwhile in helping members (and other visitors) finding their way around content that's relevant to them.   Personally, I look forward to reading both threads, with the added joy of being able to do so without having to "context switch" my mind between the technical  and line-specific issues.