supervc-10
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- 4 Mar 2012
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- 703
From 25kV? That seems like quite the drop! I'm no electrical engineer but that must have caused some issues, even if it was limited to just a reduction in tractive ability.
From 25kV? That seems like quite the drop! I'm no electrical engineer but that must have caused some issues, even if it was limited to just a reduction in tractive ability.
Gosh that Stowmarket issue was a real pain. ETS was lost to the train as soon as acceleration from Stowmarket started & it was a slow old climb up Haughley Bank.If you were inclined to guess a little further, do "supply issues" = voltage drop? I've been told, (by the electrification installation team at a Colchester open day) that when the Stowmarket feeder was offline the voltage in the area dropped to 16.5 kV, which wasn't such a problem back then. Today's electronically controlled rolling stock may not be so tolerant as 86's, etc.
Gosh that Stowmarket issue was a real pain. ETS was lost to the train as soon as acceleration from Stowmarket started & it was a slow old climb up Haughley Bank.
Almost all Norwich services called there following electrification in 87. The hourly Ipswich & Colchester only services where introduced around 2000 by Anglia. The issues with the feeder station where quite recent.I've a friend (retired Stratford driver.) who finished on 86's & Mk 2 driving trailers, I'll have to ask him for his thoughts re Stowmarket. It's possible that not many Norwich trains actually stopped there back in the early '90's.
Almost all Norwich services called there following electrification in 87. The hourly Ipswich & Colchester only services where introduced around 2000 by Anglia. The issues with the feeder station where quite recent.
Ah we are at crossed purposes. I was talking about last year when it went on for months & months. I wasnt driving that far backI've just checked the date of the respective Colchester Open day, it was 26-08-1991, so that's not really recent. The problem with Stowmarket feeder station back then was that it couldn't be used.
The quoted reason was that the single-phase load was too much for the local grid supply.
Perhaps, some 28 years later, that's no longer a problem.......
Q? What are / were the more recent issues?
If you were inclined to guess a little further, do "supply issues" = voltage drop? I've been told, (by the electrification installation team at a Colchester open day) that when the Stowmarket feeder was offline the voltage in the area dropped to 16.5 kV, which wasn't such a problem back then. Today's electronically controlled rolling stock may not be so tolerant as 86's, etc.
That's all true but surely there must be some sort of power reduction if the line voltage drops significantly. Otherwise you'll draw a correspondingly larger current from the overhead, and possibly cause damage or failure of the pantograph, wiring from panto to transformer, or the components connecting the overhead to the grid.the control electronics shouldn't be a problem.
the innards of the control system will be working at 12/24/48/110vdc and that should all be extremely well regulated.
the power electronics will be 750vdc, which might make things a bit slow off the mark if below that level.
I woluld have thought that 25KvAC stepped down to 800VAC, and then shoved through a (full wave)rectifier+capacitor bank and some zeners/shottkeys should be ample regulation to keep things stable in the event of a supply drop.
Conscious this is well off-topic, however with the BR-Era stock undervoltages would effectively just make things slower, as has been said. With more modern stock the issue that occurs / has occurred in the past is that the TMS sees a line voltage below the lower threshold cut-off and has a "computer says no" moment and shuts the unit down.the control electronics shouldn't be a problem.
the innards of the control system will be working at 12/24/48/110vdc and that should all be extremely well regulated.
the power electronics will be 750vdc, which might make things a bit slow off the mark if below that level.
I woluld have thought that 25KvAC stepped down to 800VAC, and then shoved through a (full wave)rectifier+capacitor bank and some zeners/shottkeys should be ample regulation to keep things stable in the event of a supply drop.
Passive provision for the reopening of the St. Ives branch?A follow up to my post yesterday, stop boards/changeover boards on Platform 1 at Cambridge North (southbound). No changeover boards obvious anywhere else (either end of the bidi(?) Platform 2, and I can't see the stop boards on P3 from here).
All locos and emus have a nominal voltage but also a tolerance band within which they’ve been designed to operate. I can’t find the info at the moment but I seem to remember the class 92 being OK down to about 16.5kv!Conscious this is well off-topic, however with the BR-Era stock undervoltages would effectively just make things slower, as has been said. With more modern stock the issue that occurs / has occurred in the past is that the TMS sees a line voltage below the lower threshold cut-off and has a "computer says no" moment and shuts the unit down.
The other issue with drawing more power generally is that all of the grid points have an agreed capacity with the DNO (Domestic Network Operator) and drawing more than the agreed limit gets you penalised and also has knock-on effects for the grid generally. The railway has done this quite a bit - for instance Bow Feeder was for many years feeding well over agreed capacity - but it's something that people are keen to avoid.
All locos and emus have a nominal voltage but also a tolerance band within which they’ve been designed to operate. I can’t find the info at the moment but I seem to remember the class 92 being OK down to about 16.5kv!
Anyone know where it went after Crown point? Or is it still there? Now at least 5 x 745's needing 1.25km of siding space!Another 745/0 delivery just passed through Colchester. As NNR is apparently full and Crown Point bursting at the seams, where will it stable?
That seems rather surprising. Are Stadler using any Siemens suppliers?Did hear a rumour the 745's may have same OHL issues that the other 700's have, ? as was shown last Friday when they all 'stopped' at the same time
might be unconnected of course, you know what rumours are like ! but it does seem the 745's are not happy when the voltage dropsThat seems rather surprising. Are Stadler using any Siemens suppliers?
Sounds unconnected because last Friday was reportedly mainly due to a frequency drop. Also 745 are Stadler, 700 Siemens, 710 Bombardier... seems unlikely that the same fault would afflict all unites numbered in 700s. But I guess time will tell. At least maybe 745s can be reprogrammed before entering service to avoid sitting down permanently.might be unconnected of course, you know what rumours are like ! but it does seem the 745's are not happy when the voltage drops
conspiracy theories galore...Sounds unconnected because last Friday was reportedly mainly due to a frequency drop. Also 745 are Stadler, 700 Siemens, 710 Bombardier... seems unlikely that the same fault would afflict all unites numbered in 700s. But I guess time will tell. At least maybe 745s can be reprogrammed before entering service to avoid sitting down permanently.
The Anglia region power supplies in (many) places are well known to be maxed out (i.e. North of Cambridge (cheap Kings Lynn spec in early 1990s minimal recent upgrades, no double 90s on GEML freights) and hence voltage will be very low in places but traditional stock is more tolerant as there isn't precision computer control enforcing shut down.
Yes - Only upgraded enough for GTR 8 car instead of 4 car to Kings Lynn etc. Stadler Bimodes not planned for...There was a comment in a Network Rail delivery plan in January 2019 which said that the "West Anglia Outer" traction power upgrade was completed in November 2018. It was to increase the Firm Service Capacity at King’s Lynn to 3MVA.
It was on page 26 of the PDF that was available from https://cdn.networkrail.co.uk/wp-content/uploads/2019/01/EDP-December-2018.pdf However, that link is now dead.
Is there still a problem?
I thought they were upgrading to be ready for half-hourly Kings Lynns both ways - but Ely North still prevents that so is there not some spare? But it sounds like another upgrade may be needed because of Abellio's bid - it is a shame coordination between infrastructure upgrades and service upgrades is not better.Yes - Only upgraded enough for GTR 8 car instead of 4 car to Kings Lynn etc. Stadler Bimodes not planned for...
One bit of DfT not speaking to others.I thought they were upgrading to be ready for half-hourly Kings Lynns both ways - but Ely North still prevents that so is there not some spare? But it sounds like another upgrade may be needed because of Abellio's bid - it is a shame coordination between infrastructure upgrades and service upgrades is not better.
Not really because the forerunner to this already runs as far as Ely as an 8-car.I thought they were upgrading to be ready for half-hourly Kings Lynns both ways - but Ely North still prevents that so is there not some spare? But it sounds like another upgrade may be needed because of Abellio's bid - it is a shame coordination between infrastructure upgrades and service upgrades is not better.