You'd think any dual-voltage unit would be able to transition between its voltages.
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Class 387
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You'd think any dual-voltage unit would be able to transition between its voltages.
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R
RailUK Forums
I agree.
I think as time goes on, things should be improved and tweaked (just as things generally are). Of course, some companies prefer to save money and just regurgitate the same things until they invariably end up left behind and made obsolete.
You could argue that, yes, people survived without screens on trains or automated announcements. They survived too without power points, or Wi-Fi*. LED lighting? Why bother if ordinary fluorescent tubes and halogen spot lights work fine?
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* Trains with Wi-Fi should really be seeking to get upgraded to offer 5GHz (802.11n and 802.11ac) access, which has many advantages. I think I scanned on the GWR HSTs I used last Saturday and I think they were 2.4GHz only. If so, that's a bit backwards.
2.4GHz may travel further, but there are a range of congestion and capacity issues. Many new hotspots are dual mode, and can cope with more users far more effectively. I'd say that most tablets and smartphones made and sold in the last two years are going to be dual-mode (bar the very cheapest models). Laptops probably for even longer.
Peter Sarf
Established Member
I am not totally sure but I think there are never both supplies available simultaneously. This is because I believe that there are relays ON THE PERMANENT WAY allowing only one of 25KV AC -OR- 750V DC to be live at one point in time. This is because the earth for both is the same. I do not know how the infrastructure decides which supply gets a completed circuit via the earth/return but I suppose that means that there is a gap in time between one becoming un-live and the other becoming live.
So the train would have to know that this was just a loss of power supply for a short gap in time. Or the train could have enough battery backup, for the systems that are not desperately important, to keep them going for say 60 seconds regardless of the reason.
I am sure that some of the above could possibly be wrong but perhaps the last paragraph gives an idea of what could be done.
Old laptops/PDA's had battery backed ram and, of course, laptops can be run from battery or mains and can handle any one of these two being lost without the need to reboot.
A small battery (it wouldn't need to be greater than 1,000 mAh esp. If only the processor/memory subsystem and not the screen is kept alive) would do the job. Yes you would need a small amount of extra electronics to manage the battery charging, power management (battery/line supply changeover) and to create all the necessary voltages (probably +3.3V, +5V and +12V) for the main board.
This should be relatively simple and shouldn't need to be any bigger than a fat smartphone.
A small battery (it wouldn't need to be greater than 1,000 mAh esp. If only the processor/memory subsystem and not the screen is kept alive) would do the job. Yes you would need a small amount of extra electronics to manage the battery charging, power management (battery/line supply changeover) and to create all the necessary voltages (probably +3.3V, +5V and +12V) for the main board.
This should be relatively simple and shouldn't need to be any bigger than a fat smartphone.
swt_passenger
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That is not generally true, at the changeover point both supplies are available at the same time.
To the best of my knowledge it is only the Thameslink core section between Farringdon and City Thameslink inclusive where there is contactor control of the dual voltage section, but only to the extent that the overlap sections can be effectively 'repositioned', however the actual point where the changeover is happening still has both supplies available at the same time.
To explain that differently, there is no need for that particular dual electrified section to run all the way through both stations, on both up and down lines, but it can be switched from one place to the other, or somewhere inbetween, depending on what is required at the time.
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Yep, the power is on to both systems at all times. What the contractor system does is alter the earthing arrangements on the track under each train through the dual voltage section. This is encourage the DC return through the (bonded) DC return system, and the AC return through the (earthed) AC return system. Otherwise the resistance in the DC return system would cause all DC return to try and get to the AC system. With rather detrimental effects on the signalling, not least the insulated block joints. There's one at the south end of Blackfriars that gets arcing regularly, the top of the rail head is not pretty.
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4-COR 3142
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So are the /2's still running 08:35am Bletchley TMD and back at 19:11 via Brighton or do the timings vary?
The Bletchley to Brighton run is as required as is the Northern counterpart to Crewe and back.
There doesn't seem to be any pattern at all and the best thing to do is just look on real time trains for Bletchley after 08.30 on a weekday to see if it runs.
trainmania100
Established Member
387206 and 207 ran the 5B89 to Brighton yestersay
Bombardier representative said they are hoping to run 12 car test soon , depending on software engineer availability
Kite159
Veteran Member
Saw a trio of 387/2s heading down south passing Gatwick Airport around 12:50 earlier, first time I've seen them in the metal.
Very red and shiny
Very red and shiny
Class377/5
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387208 (south)/205/207 today.
swt_passenger
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A poster in the UKModernEMU Yahoo group reported sighting it through Bow Brickhill.
And a video from Clapham Jn.
https://www.youtube.com/watch?v=ci6sg1lvlFE
I'll be interested to see where the First Class will be located even though there is no sign of it.
southern442
Established Member
I believe there is a bit sectioned off that is EXACTLY THE SAME as standard againnnnn :roll: (ok hopeless moaning over) but when I saw a couple on testing (and I believe you can see it on the video) that there is a bit of one of the driving coaches that is separated off.
southern442
Established Member
Exactly. Designed for airport travellers? I think not.
Yep,no thought for customers needs again. The only advantage on 442s is the doors. They basically are a 387/1 with different colours.
southern442
Established Member
Are they an add-on? I thought that a 442 replacement was always planned, and it just so happens that they are gonna be classified as 387/2's cause they are otherwise the same as them. Or did GTR just jump on the 'throw electrostars at the problem' bandwagon to get rid of the 442's quicker?
442 replacement may well have been planned, but the original 387 order had a 140 carriage optional add on which GTR chose to use for new Gatwick Express units, the remainder of the add on being used for 8 new GWR units, so the fact they basically the same as the original batch of 387's with a different colour scheme doesn't exactly surprise me.
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swt_passenger
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Replacing the 442s was not being discussed publicly until the GoVia bid details appeared. I think most people were surprised on the day. I don't recall it being an explicit requirement of the ITT.
I don't think it came as a surprise. Although not explicitly required to replace the 442s the ITT strongly hinted at it by saying that they would be interested to see bids with rolling stock more suited to the needs of airport passengers as a way of exceeding the requirements.
Shouldn't they have got trains more suited then? Better access, yes. Sufficient luggage storage for people going to from the airport? No.
The trains might be the same in terms of build but surely the interior layout can be varied within that build? The seats are obviously a different colour and the livery is different. I can't imagine they couldn't remove some more seats for even more luggage racks?
The trains might be the same in terms of build but surely the interior layout can be varied within that build? The seats are obviously a different colour and the livery is different. I can't imagine they couldn't remove some more seats for even more luggage racks?
exactly. It would 've easy. Unfortunately I dont think there is anyone in the company at that level who cares about passengers needs.
D365
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As an 'airport express' train, are the Class 379s any better in this regard? I am not familiar with the on-board stowage arrangement for trains originating at a UK airport.
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