Recent Public Posts - [guest]
Re: Suitable train sets In "Bristol (WECA) Commuters" [359711/30047/21] Posted by John D at 08:08, 22nd March 2025 | ![]() ![]() ![]() ![]() ![]() |
Even after the 175s arrive, still not going to be a very good match for GWR services
The 10 2car 175s could take over a few Paignton, Exmouth services from 150s, but their longer distance seating and door layout is not ideal. For most other services operating them as just 2car is likely to give capacity problems at certain times
The 16 3car units will be more useful, although there are number of services to Barnstaple, Oakhampton, Newquay etc where passenger numbers ideally means they will need to be longer formations. However some of these services have stations where joined units don't fit platforms (or guards cannot easily check tickets in both units). My understanding is don't have selective door opening, it is front unit only and back unit not open, or all doors only.
Struggling to see how the allocations on the busy services will work, will it be 2 or 3 or 2+2 or 2+3 or 3+3 formations.
There was earlier comment about lack of 5car formations on Portsmouth-Cardiff. Currently GWR have 41 class 158 vehicles, most are 2car, there is one 3car unit, and 4 units bodged into 3car made up from 6 2car units (so middle vehicle has a driving cab). Clearly 41 vehicles is not enough to operate 8 trains of 5 vehicles and have spares for maintenance. As they are about 35 years old scheduling them at nearly 100% usage is never going to be reliable, so realistically about 2 in 8 Portsmouth-Cardiff services are always going to have unsuitable stock (even after 175s cascade trains)
So short term that leaves the 165 units (built for branch lines and local suburban workings), but often used by GWR on long services to places like Worcester, Weymouth etc. Again hardly in the suitable train type category on these extended workings. At least they have had a refresh, which partly hides their 33 years old age.
Then there are the 166s, all 3car, and often used as single units even on the quasi-intercity Cardiff-Portsmouth service (a route that serves 7 cities, a rather higher number than some mainline services). But a 166 was never built and specified as a regional train, it was (and still is as seating has never been reconfigured) an outer suburban commuter train. These days seem to be used randomly as common fleet with 165s (rather than being dedicated to the longer workings). Actually not uncommon to see a 165 and 166 coupled. Basically these are 32 year old hand-me-downs
Then GWR have the (now split at Exeter) Cardiff-South West workings. Logically they would have identical fleet to Cardiff-Portsmouth. But no, GWR has opted for 5car IETs (not because they are ideal, but because it is all that could be spared). And yes they can at least run on electric Cardiff-Patchway (unlike the Cardiff-Portsmouth services which use old emissions spec diesel throughout, even though Cardiff-Patchway and Redbridge-Portsmouth are electrified). Again questionable if they are suitable type, or simply spare hand-me-downs.
As for using IETs on some Bristol-Worcester services, don't get me started as to why GWR have ended up with so many 5car IETs instead of full length ones, but having got them (and abandoned the splitting of services they were ordered for, because software too slow to reconfigure during coupling/uncoupling) need to utilise the excess quantity of short IETs somewhere.
Off record, personally wouldn't be too sorry if over half the 5car IETs were returned to leasing companies (and there are plenty of more suitable services around the UK that could use them better) and GWR ordered some comfortable 110-125mph battery EMUs for services to Oxford, Bedwyn, Warminster, Frome, Gloucester etc.
Re: North Cotswold line delays and cancellations - 2025 In "London to the Cotswolds" [359710/29711/14] Posted by Worcester_Passenger at 06:31, 22nd March 2025 Already liked by Mark A | ![]() ![]() ![]() ![]() ![]() |
Saturday March 22
Starting the Hereford from Oxford doesn't count:
06:18 Hereford to London Paddington due 09:24 will be started from Oxford.
This is due to a shortage of train crew.
Last Updated:22/03/2025 03:03
This is due to a shortage of train crew.
Last Updated:22/03/2025 03:03
Re: Paddington bear stolen,now recovered In "The West - but NOT trains in the West" [359709/29972/31] Posted by infoman at 05:25, 22nd March 2025 | ![]() ![]() ![]() ![]() ![]() |
Two RAF engineers have been charged over removal
https://www.thesun.co.uk/news/33954796/royal-air-force-crew-stealing-paddington-bear/
Re: Heathrow Airport closed all day Friday 21 March 2025 In "Buses and other ways to travel" [359708/30050/5] Posted by broadgage at 00:32, 22nd March 2025 | ![]() ![]() ![]() ![]() ![]() |
Agree that a UPS provides "no break power" rather than "firing up in seconds"
My relatively cheap UPS provides power without any detectable break, to loads that I consider important (fridge freezer, some lighting, internet router, cordless phone base unit, cellphone charger. It runs indefinitely on mains power and for about 24 hours on battery.
It cost about £50 for the UPS and about £200 for the long run time batteries.
Much larger units are available, up to MEGAWATTS.
Re: Shortage of train crews on Great Western Railway - ongoing discussion In "Across the West" [359707/18719/26] Posted by UstiImmigrunt at 22:20, 21st March 2025 | ![]() ![]() ![]() ![]() ![]() |
Another 3 HSS BTM drivers retired today... With full depot route knowledge that won't be replaced.
Re: 2025 - Service update and amendment log, Swindon <-> Westbury In "TransWilts line" [359706/29726/18] Posted by grahame at 20:41, 21st March 2025 | ![]() ![]() ![]() ![]() ![]() |
Just gotta get home now 

How it should work (timing wise) - 17:53 from Taunton to Bristol, 18:30 on to Chippenham and 19:00 to Melksham arrived 1 minute down at 19:09 - 76 minute journey.
Re: Heathrow Airport closed all day Friday 21 March 2025 In "Buses and other ways to travel" [359705/30050/5] Posted by Clan Line at 17:36, 21st March 2025 Already liked by broadgage | ![]() ![]() ![]() ![]() ![]() |
............ hefty UPS (Uninterruptible Power Supply) battery packs which automatically fired up in a matter of seconds in the event of a mains power failure .............
Sorry Bob - but you are making unsubstantiated statements about Heathrow and the National Grid. To provide full backup power for Heathrow ("as much energy as a small city") is economically impossible to contemplate.
I regret to say that your statement regarding UPS is also a little wide of the mark. A UPS does not "fire up in a matter of seconds" when power is lost (in today's digital age this this could be equally catastrophic) - it is on line all the time. A "proper" (not £9.99 from Amazon) UPS is usually fed from a battery, this battery is kept fully charged by the mains supply - if the mains supply fails the UPS continues to supply the load, now depending solely on the battery. There is NO break in the UPS output. This continues for the time specified by the customer. This normally gives the time required to get the diesel up and running - or for non-critical equipment, to carry out a controlled shut down.
Re: Heathrow Airport closed all day Friday 21 March 2025 In "Buses and other ways to travel" [359704/30050/5] Posted by Electric train at 17:26, 21st March 2025 Already liked by Mark A | ![]() ![]() ![]() ![]() ![]() |
A location of stratigic National importance such as Heathrow should have a robust backup system whilst they 100% may not be warranted they should be able to run core business at a acceptable degraded mode
As I said, the "robust back up system" did work, if an aircraft HAD to land at Heathrow last night it could have done so safely. Trying to keep an airport running when everything around it has failed is just asking for even more trouble. "Degraded mode" = what ? Burger King open but not McDonalds ?
Strangely enough, before I retired, I actually worked at an airport setting to work a "robust back up system" such as is probably installed at Heathrow - albeit on a much larger scale at Heathrow. This was not designed to keep the airport restaurants running at that airport either.
My current job is looking after the traction power system for a large chunk of South London along with a number of major London stations. There are always weak spots in a system especially older systems, the modern systems can operate a N-1 including a total loss of a National Grid connection in SE London, a reduced service would have to be implemented but it would not be a total shut down
Re: Heathrow Airport closed all day Friday 21 March 2025 In "Buses and other ways to travel" [359703/30050/5] Posted by Clan Line at 17:08, 21st March 2025 | ![]() ![]() ![]() ![]() ![]() |
A location of stratigic National importance such as Heathrow should have a robust backup system whilst they 100% may not be warranted they should be able to run core business at a acceptable degraded mode
As I said, the "robust back up system" did work, if an aircraft HAD to land at Heathrow last night it could have done so safely. Trying to keep an airport running when everything around it has failed is just asking for even more trouble. "Degraded mode" = what ? Burger King open but not McDonalds ?
Strangely enough, before I retired, I actually worked at an airport setting to work a "robust back up system" such as is probably installed at Heathrow - albeit on a much larger scale at Heathrow. This was not designed to keep the airport restaurants running at that airport either.
Re: Heathrow Airport closed all day Friday 21 March 2025 In "Buses and other ways to travel" [359702/30050/5] Posted by TaplowGreen at 16:42, 21st March 2025 | ![]() ![]() ![]() ![]() ![]() |
Flights resuming later today - pretty impressive recovery all in all............
From the BBC
We've just received a fuller statement from Heathrow Airport, which says it can restart some flights later today and hopes to be fully operational tomorrow:
"Our teams have worked tirelessly since the incident to ensure a speedy recovery. We're pleased to say we're now safely able to begin some flights later today.
"Our first flights will be repatriation flights and relocating aircraft. Please do not travel to the airport unless your airline has advised you to do so.
"We will now work with the airlines on repatriating the passengers who were diverted to other airports in Europe. We hope to run a full operation tomorrow and will provide further information shortly.
"Our priority remains the safety of our passengers and those working at the airport. As the busiest airport in Europe, Heathrow uses as much energy as a small city, therefore getting back to a full and safe operation takes time. We apologise for the inconvenience caused by this incident."
Re: Heathrow Airport closed all day Friday 21 March 2025 In "Buses and other ways to travel" [359701/30050/5] Posted by Electric train at 16:37, 21st March 2025 | ![]() ![]() ![]() ![]() ![]() |
There is either a serious design flaw, lack the right switchgear systems / control system or lack of competent people
Very profound statement - based on

Perhaps the substation control room was pretty close to the fire - or the blast wall (well illustrated by MarkA) was about to collapse - and the night shift decided to leave ..............quickly !
Stuving has summarised what did happen at Heathrow itself............everything essential worked ! The airport was still capable of handling aircraft - even if that was only to tell them to go elsewhere.
Closing the airport entirely was the correct decision............imagine the chaos today if they hadn't.
Just supposing Heathrow had 100% electricity back up (at what enormous cost ?) - the surrounding area had lost all power. No trains, no properly functioning roads (M4 was/is shut), no nothing ! What would be the point of trying to keep the airport open ?
What happened at North Hyde will unfold - making unfounded statements will help no one in the mean time.
There is no control room at North Hythe, NG operations control is in Sindlesham, Wokingham in Berkshire, SSE and UKPN have theirs located in a number of places in the UK.
I was refereeing to the control of electrical power within Airport
A location of stratigic National importance such as Heathrow should have a robust backup system whilst they 100% may not be warranted they should be able to run core business at a acceptable degraded mode
Re: Heathrow Airport closed all day Friday 21 March 2025 In "Buses and other ways to travel" [359700/30050/5] Posted by Bob_Blakey at 16:33, 21st March 2025 | ![]() ![]() ![]() ![]() ![]() |
I am taken back to the late 1980's when I started my employment with a large telecommunications company that had just established a new data centre (DC) in Exeter. The DC supported all the company's business application IT for Cornwall (inc. the IoS), Devon and a significant part of Somerset. Staff numbers were around 150 people and it was a 24/7 operation.
Pretty small beer compared to Heathrow Airport.
As part of the new employee 'tour' we discovered that the building had two separate mains power supplies, which could be switched over very rapidly, two fairly hefty UPS (Uninterruptible Power Supply) battery packs which automatically fired up in a matter of seconds in the event of a mains power failure, and a diesel generator which could be brought online in 10 minutes . These units were fully tested on a quarterly basis.
It seems to me that, given the importance of LHR in the national picture, Heathrow Airport management, possibly aided & abetted by the National Grid, have completely failed to render the site as operationally secure as should have been the case (e.g. automatic switching to one of the alternative mains power supplies should have been an absolute requirement).
Re: Heathrow Airport closed all day Friday 21 March 2025 In "Buses and other ways to travel" [359699/30050/5] Posted by Clan Line at 15:58, 21st March 2025 | ![]() ![]() ![]() ![]() ![]() |
There is either a serious design flaw, lack the right switchgear systems / control system or lack of competent people
Very profound statement - based on

Perhaps the substation control room was pretty close to the fire - or the blast wall (well illustrated by MarkA) was about to collapse - and the night shift decided to leave ..............quickly !
Stuving has summarised what did happen at Heathrow itself............everything essential worked ! The airport was still capable of handling aircraft - even if that was only to tell them to go elsewhere.
Closing the airport entirely was the correct decision............imagine the chaos today if they hadn't.
Just supposing Heathrow had 100% electricity back up (at what enormous cost ?) - the surrounding area had lost all power. No trains, no properly functioning roads (M4 was/is shut), no nothing ! What would be the point of trying to keep the airport open ?
What happened at North Hyde will unfold - making unfounded statements will help no one in the mean time.
Re: Heathrow Airport closed all day Friday 21 March 2025 In "Buses and other ways to travel" [359698/30050/5] Posted by IndustryInsider at 15:37, 21st March 2025 | ![]() ![]() ![]() ![]() ![]() |
Plus, there's money to be made!
I saw reports that hotels were exploiting the situation by doubling, tripling and perhaps more, their standard room rates.
Re: Heathrow Airport closed all day Friday 21 March 2025 In "Buses and other ways to travel" [359697/30050/5] Posted by stuving at 15:35, 21st March 2025 Already liked by Mark A, PrestburyRoad | ![]() ![]() ![]() ![]() ![]() |
Eorostar have been running a few extra trains today - four, according to French TV news, though I could only see two when I looked online. Not much, in terms of the total number of diverted passengers, but no doubt it's good publicity to do something (and bad to do nothing). Plus, there's money to be made!
Re: Heathrow Airport closed all day Friday 21 March 2025 In "Buses and other ways to travel" [359696/30050/5] Posted by stuving at 15:31, 21st March 2025 | ![]() ![]() ![]() ![]() ![]() |
From the BBC, in a page with further details:
With Heathrow being such a busy airport for passenger journeys and global trade, questions have been raised over whether it has back-up systems in the event of power cuts.
The BBC understands that Heathrow does have back-up power for its key systems, but kickstarting these alternative power supplies for the whole airport takes time.
A source said it was not possible to switch the power back on immediately.
A Heathrow source also told the BBC that they have "multiple sources" of energy at the airport – with diesel generators and "uninterruptable power supplies" in place.
They added when the power outage happened the back up systems "all operated as expected".
The systems, however, are not enough to run the whole airport – hence the decision to close it down.
The source said the airport is in the process of redirecting power to the affected parts of the operation – but that it "takes time".
And even once the power is back on, there are countless systems which need to be rebooted and checked to ensure they are working properly and are stable.
The BBC understands that Heathrow does have back-up power for its key systems, but kickstarting these alternative power supplies for the whole airport takes time.
A source said it was not possible to switch the power back on immediately.
A Heathrow source also told the BBC that they have "multiple sources" of energy at the airport – with diesel generators and "uninterruptable power supplies" in place.
They added when the power outage happened the back up systems "all operated as expected".
The systems, however, are not enough to run the whole airport – hence the decision to close it down.
The source said the airport is in the process of redirecting power to the affected parts of the operation – but that it "takes time".
And even once the power is back on, there are countless systems which need to be rebooted and checked to ensure they are working properly and are stable.
I would not surprised if international standards require critical systems for air operations - navigation aids, and everything that allows an aircraft to land and clear the runway at least - to be backed up independently of outside supply, and perhaps with backups for those backups. That much they are saying did work as intended.
I wonder if the fact that that was in place meant they did not worry so much about security of external supplies. So everything not critical got handled on the basis of manually reconfiguring the network - but remember that this is a big part of supply resilience at all levels (it's why restoring supply, as this morning around the dead GSP, takes several hours). And as they say, running an airport safely, even in an emergency basic no-frills mode, needs a lot more power that they (and their DNO(s)) can restore via new routes within a few hours. In this case that was the result of a commercial decision made by HAL.
Re: Rolling stock projections - ongoing discussion In "Looking forward - the next 5, 10 and 20 years" [359695/26134/40] Posted by Clan Line at 15:20, 21st March 2025 | ![]() ![]() ![]() ![]() ![]() |
Dividing last two suggests GWR trains have average 5.93 carriages, which is rather more than most local services in Wessex get
I have noticed that, of late, the promised "5 car" service for Cardiff - Portsmouth has now shrunk to one 5 car formation doing one round trip per day - and that only actually becomes 5 cars at Temple Meads on the outbound leg ! So don't join it at Cardiff expecting plenty of empty seats .........
Re: 2025 - Service update and amendment log, Swindon <-> Westbury In "TransWilts line" [359694/29726/18] Posted by grahame at 15:05, 21st March 2025 Already liked by Mark A | ![]() ![]() ![]() ![]() ![]() |
Problems had started this morning ... I walked to the station and saw the dreaded word "delayed" against the 09:10 to Westbury. Checking Open Trains Times and Real Time Trains and another regular checked on her phone other sources, and on principle asking on the help point too, we were told 09:31 and that the connection at Trowbridge to Bath and Bristol would make, and a couple of minutes later Open Train Times map showed it coming. Display changed to 09:34 which was going to be really tight at TRO. No clues as to why ...
Good TM when it rolled in / explained about a point or track failure at Swindon and apologised - "I realise you don't have much information available at Melksham" which shows an excellent understanding. Connection to Bath and Bristol made. Connection to Warminster was lost / 30 minute delay to there. I'm not aware of where others were connecting to.
Just gotta get home now

Re: Heathrow Airport closed all day Friday 21 March 2025 In "Buses and other ways to travel" [359693/30050/5] Posted by Electric train at 14:20, 21st March 2025 | ![]() ![]() ![]() ![]() ![]() |
The nominal supply area for North Hyde GSP is attached - it does not include much of the airport.
But just happens to be Term 2 & 4 along with ATC and other critical infrastructure
But of course the big question is why the multiple supply routes to the airport did not give it a resilient supply. That's for HAL and perhaps SSEN to answer, rather than NGESO.
There is either a serious design flaw, lack the right switchgear systems / control system or lack of competent people
Re: Heathrow Airport closed all day Friday 21 March 2025 In "Buses and other ways to travel" [359692/30050/5] Posted by stuving at 13:25, 21st March 2025 | ![]() ![]() ![]() ![]() ![]() |
Heathrow's supply comes from at least two grid supply points, the nearest two being North Hyde to the north (the one that went bang) and Laleham to the south. But there are others further away that could be included if resilience is the valued highly enough. SSEN distribute power from both, but UKPN also operate at Laleham. The nominal supply area for North Hyde GSP is attached - it does not include much of the airport. But of course the big question is why the multiple supply routes to the airport did not give it a resilient supply. That's for HAL and perhaps SSEN to answer, rather than NGESO.
Re: Heathrow Airport closed all day Friday 21 March 2025 In "Buses and other ways to travel" [359691/30050/5] Posted by Mark A at 13:01, 21st March 2025 | ![]() ![]() ![]() ![]() ![]() |
Thanks for that. Ah. Blast walls. That reminded me of my unhealthy interest in taking photos of electricity-related infrastructure. Here's a photo of a transformer and associated set of blast walls on the site of Bath's vanished power station. I'm rather hoping that there's some additional structure within what is otherwise a rather tall brick wall that you'd think would be prone to being pushed over if anything gave it enough of a nudge.
Mark

Bristol and north Somerset Railway remains from the bus... In "Railway History and related topics" [359690/30051/55] Posted by Mark A at 12:47, 21st March 2025 Already liked by Witham Bobby | ![]() ![]() ![]() ![]() ![]() |
Returning from Bristol yesterday on the bus, and going the long way round had me wondering if any coffeeshop forum people had any recollections of the B&NS railway when it was a going concern. Myself, in the 1990s, I recall seeing the ruin of Brislington's station from Talbot Road, very visible but I never attempted to visit it or take a photo.
Given that the passenger service folded in 1959, that might be too long ago for memory.
The... is it the 522 bus... in the direction of Radstock gives the impression, when it leaves Bristol, of climbing interminable hills (and descending a fair few) but at the top of several of the climbs, some relic or other from the old line, looking rather improbable given the hill that the bus has just climbed. The bridge taking the line beneath the Chelwood roundabout vanished several years ago when the roads were reworked there...
If it's not a post closure embankment slip, it appears that LIDAR data from north of Pensford might still show the site of the 1968 washout that ended the line's use for freight.
https://maps.nls.uk/geo/explore/#zoom=18.6&lat=51.37632&lon=-2.55033&layers=258&b=LIDAR_DTM_1m&o=39
All rather a long time ago, and a line that had a complicated and checquered story to both its creation and its demise. Curious that just a few hundred metres of it and at least one (obscure) structure are still in rail industry use, photo below.
Mark

Re: 2025 - Service update and amendment log, Swindon <-> Westbury In "TransWilts line" [359689/29726/18] Posted by TaplowGreen at 12:45, 21st March 2025 | ![]() ![]() ![]() ![]() ![]() |
12:17 Westbury to Swindon due 12:59
12:17 Westbury to Swindon due 12:59 will be cancelled.
This is due to a points failure.
13:14 Swindon to Westbury due 13:57
13:14 Swindon to Westbury due 13:57 will be cancelled.
This is due to a points failure.
14:18 Westbury to Swindon due 15:00
14:18 Westbury to Swindon due 15:00 will be terminated at Chippenham.
It will no longer call at Swindon.
This is due to a points failure.
15:15 Swindon to Westbury due 15:59
15:15 Swindon to Westbury due 15:59 will be started from Chippenham.
It will no longer call at Swindon.
This is due to a points failure.
Re: 2025 - Service update and amendment log, Swindon <-> Westbury In "TransWilts line" [359688/29726/18] Posted by TaplowGreen at 12:43, 21st March 2025 | ![]() ![]() ![]() ![]() ![]() |
Cancellations to services between Swindon and Westbury via Melksham
Due to a points failure at Swindon some lines are blocked. Disruption is expected until 15:00 21/03.
Train services between Swindon and Westbury via Melksham may be cancelled or delayed.
Customer Advice
Apologies for the disruption to your journey today.
Network Rail advise that a set of points has failed just outside Swindon station; this is affecting journeys in both directions as local services are caught up in the congestion on the Main Lines.
Re: Heathrow Airport closed all day Friday 21 March 2025 In "Buses and other ways to travel" [359687/30050/5] Posted by CyclingSid at 12:25, 21st March 2025 Already liked by Mark A | ![]() ![]() ![]() ![]() ![]() |
I have to acknowledge that I am not a great fan of another runway at Heathrow.
"It certainly seems Heathrow's eggs are all in one basket." Adding another runway would make the situation worse; Gatwick, o
Luton or Stansted if you must.
Is all this another example of induced demand, as seen on roads? Build more and you get more, ad infinitum. Ironic that there is another closure of the M25 this weekend.
Re: Heathrow Airport closed all day Friday 21 March 2025 In "Buses and other ways to travel" [359686/30050/5] Posted by TaplowGreen at 12:17, 21st March 2025 | ![]() ![]() ![]() ![]() ![]() |
Power has been restored to Terminals 2 & 4 which were apparently the worst affected.
Re: North Cotswold line delays and cancellations - 2025 In "London to the Cotswolds" [359685/29711/14] Posted by Worcester_Passenger at 11:27, 21st March 2025 | ![]() ![]() ![]() ![]() ![]() |
Friday March 21
09:55 Great Malvern to London Paddington due 12:23 will be terminated at Worcester Shrub Hill.
This is due to a shortage of train crew.
Last Updated:21/03/2025 10:25
This is due to a shortage of train crew.
Last Updated:21/03/2025 10:25
Later:
19:53 London Paddington to Hereford due 22:57 will be cancelled.
This is due to a shortage of train crew.
Last Updated:21/03/2025 17:53
Does not bode well for tomorrow's 1P13 06:18 Hereford to London Paddington.This is due to a shortage of train crew.
Last Updated:21/03/2025 17:53
Re: Heathrow Airport closed all day Friday 21 March 2025 In "Buses and other ways to travel" [359684/30050/5] Posted by Electric train at 10:57, 21st March 2025 Already liked by Mark A | ![]() ![]() ![]() ![]() ![]() |
Is this a single point of failure?
How many other airports/airfields could be at similar risk?
Hope somebody has a spare transformer in the (very big) cupboard.
How many other airports/airfields could be at similar risk?
Hope somebody has a spare transformer in the (very big) cupboard.
It certainly seems Heathrow's eggs are all in one basket. It is poor resilience planning on the part of the Airport and the Electricity Supply Industry.
There seems to have been an internal catastrophic arc fault inside the transformer. These transformers have a device called a Buchholz relay https://en.wikipedia.org/wiki/Buchholz_relay which trips the supply and outgoing circuit breakers in the event a surge (oil / gas) and if it detects any gassing over a period of time.
Any arc internally will produce gasses, Hydrogen, Oxygen and Acetylene, also it has to be born in mind that an electric arc in what is in effect a sealed container produces extreme explosive pressure.
It is normal practice for large Grid transformers to have transformer monitoring systems such as https://camlingroup.com/kelvatek/asset-monitoring/asset-monitoring-products/transformers-monitoring and have a constant remote condition monitoring to a control centre.
What I have noticed is the lack of blast wall between the two 400/275kV / 123kV transformers (main and reserve transformers) and from the news feeds I have seen the second transformer has suffered fire damage which make a recharge of it unlikely.
I will say the "rumours" of a carelessly discarded cigarette is extremely unlikely, transformer mineral insulating oil has a very high flash point greater than 140C Grid sites have been strictly no smoking areas for many years
Re: Heathrow Airport closed all day Friday 21 March 2025 In "Buses and other ways to travel" [359683/30050/5] Posted by broadgage at 10:41, 21st March 2025 | ![]() ![]() ![]() ![]() ![]() |
Is this a single point of failure?
How many other airports/airfields could be at similar risk?
Hope somebody has a spare transformer in the (very big) cupboard.
How many other airports/airfields could be at similar risk?
Hope somebody has a spare transformer in the (very big) cupboard.
Unless a spare transformer is stored on site, or very nearby, replacement will take some time, and may require special manufacture.
I would expect power to be restored within a day or so, via an alternative route and from another transformer. This may have been achieved already.
Restarting the complex systems at Heathrow probably takes some time.
In the meantime, if an emergency requires this, aircraft could almost certainly still land.
Re: Heathrow Airport closed all day Friday 21 March 2025 In "Buses and other ways to travel" [359682/30050/5] Posted by Ralph Ayres at 10:05, 21st March 2025 | ![]() ![]() ![]() ![]() ![]() |
Possibly not much point running an excess of trains to/from Heathrow today, as it might just encourage intending passengers to turn up and wait in vain. Still staff needing to get there though some may have been told not to bother coming in, and it's also quite a useful coach travel hub for non-air travel, assuming the bus/coach station has enough power to operate (ditto of course the various rail stations).