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 31 
 on: Yesterday at 07:57:06 
Started by Mark A - Last post by Electric train
The Times this morning had a quote from "energy bosses" that a "very strong oscillation in the electrical network" led to disconnection from "the European system" - i.e. France. I have not heard that anywhere else, so either the Times is very good at digging out sources, or it's wrong. Since it's what such bosses would have said if asked in advance what was the most likely cause of a hypothetical transmission grid collapse, perhaps it was basically a guess - by someone.

At a more recent press conference, the start of the collapse was said to be the disconnection of five (I think) nuclear generators, supplying more than half of of the demand at the time. Now, something must have caused that, and oscillation (instability) fits that bill. After that, total collapse was almost inevitable - it could only be avoided if the links from France (and Morocco, much smaller) could supply most of that deficit (15 GW» (Great Western - used as an abbreviation for the area / lines under the Great Western franchise, as opposed to FGW which includes "First", the company operating them too. For tickets - about)), which sounds pretty unlikely.

Those links from outside all overloaded and tripped, though for the south-west of France the split was within France. They had to break the connection at the Pyrenees before resupplying from the French aside. The powering up of Iberia was done starting from the areas that could be supplied from abroad, in he north and south.

That sounds like the process I would expect to see. Starting the generators in a grid involves them following a grid already supplying power, so that was done using the external links. As much of the grid as could be supplied by those infeeds, at the north and south, was turned on and the generators in that area started up. That gives enough surplus power to prime the next areas and get them going.

There is some concern with Grid systems that rely heavily on renewable generation of the lack of inertia that spinning mass generation provides.  In the event of a fault on the transition system the Voltage takes longer to stabilise with  renewables based generation, Power Factor is also something more challenging the manage.

Black starting power stations ie a power station that has no live Grid takes time even natural gas fuelled.

It will be interesting to see the finding of the instigation

I have long held the view that ALL new electric trains should be equipped with either a diesel engine or a battery able to move the train at a much reduced performance for a reasonable distance.
In stating this, I was thinking primarily of UK (United Kingdom) conditions, but it looks as though it would be prudent overseas also.

At least affected passengers were allowed off the trains, in contrast to the UK policy of "keep them on the trains no matter what."

On a more general note, there appears to have been a regrettable lack of both battery emergency lighting and standby generation in public buildings.
.

In the case of UK electrified railways the loss of traction power results in the loss of power to signalling, normally not a problem as there are independent locally sourced DNO (Distribution Network Operator) supplies; however should an Iberian Peninsular type of failure occur there would be no DNO available.  And no putting generators everywhere of UPS's large enough to run for hours is not economically practical ................... quite simply the travelling public are not willing to cover the cost for what is an extremely rare event

 32 
 on: Yesterday at 07:55:47 
Started by grahame - Last post by grahame
Journey check has recently been adding explanations of technical issue and, whilst the more experienced of us may give a wry smile and say "surely we all know that" ... actually some of guest readers may not.  I suspect these explanations are prepackages chunks of text - I may be starting a collection here

Quote
We've received a report from Network Rail of a track circuit failure at Yeovil Pen Mill.

Track circuits help Signallers know if a section of the track has a train on it. If the track circuit fails, trains need to stop at each affected signal and speak to the Signaller to confirm the track ahead is clear. This can lead to delays, especially if mutliple track circuits have failed.

 33 
 on: Yesterday at 07:36:56 
Started by grahame - Last post by grahame
From https://www.wiltshire.gov.uk/localtransportplan

Quote
Wiltshire Local Transport Plan 4 (LTP4)

The fourth Wiltshire Council Local Transport Plan 2025 -2038 (LTP4) was endorsed at full council on 11 March 2025.

LTP4 sets out Wiltshire Council's strategic transport objectives, using a place-based approach that aligns with the Wiltshire Local Plan. It is designed to address the needs of three distinct areas: principal settlements, including Salisbury, Trowbridge, and Chippenham; market towns; and rural communities.

By tailoring the plan to these specific areas, the council can better respond to their unique transport challenges, recognising that the needs of rural residents differ from those in towns and cities. This approach also increases opportunities to secure additional government funding to enhance transport infrastructure across the county.

 34 
 on: Yesterday at 07:28:25 
Started by Mark A - Last post by IndustryInsider
At least affected passengers were allowed off the trains, in contrast to the UK (United Kingdom) policy of "keep them on the trains no matter what."

These, and other, anecdotes suggest that wasn’t the case:

https://apnews.com/article/spain-portugal-power-outage-electicity-train-transport-8f22b5d7a760298773cd2659eb34a58a

 35 
 on: Yesterday at 06:26:01 
Started by Chris from Nailsea - Last post by UstiImmigrunt
It is forecast to be into the mid 20s today in Ústí nad Labem.

 36 
 on: April 29, 2025, 23:56:15 
Started by Chris from Nailsea - Last post by Chris from Nailsea

I put the shorts on for the first time this year.


Too much information.  Shocked


 37 
 on: April 29, 2025, 23:31:53 
Started by Mark A - Last post by broadgage
Perhaps surprisingly, large grid systems are not well understood.
They are much too big and expensive to build a spare one for experiments. Only small and low risk tests and experiments can be performed on a working grid system.

Computer modelling is of limited use in view of the many variables, many of which change in unknown or unpredictable ways.

In recent years several factors have "conspired" to increase instability.
1) The increased use of switched mode power supplies. These draw roughly constant watts over a wide range of voltages, and can draw unexpectedly large currents during a supply voltage dip, this tends to increase the degree of voltage drop and may result in what would otherwise have been a brief voltage dip, now becoming a "fail to recover" event.
Note that variable speed motor drives and electronic lighting ballasts are all sub-species of switched mode power supplies.

2) Increased amounts of generation connected via static inverters rather than consisting of traditional rotating alternators.
Such sources CANNOT supply extra energy in a low voltage or low frequency emergency.

3)Increased geographical areas supplied by a common grid system. This tends to promote instability.

I expect more such outages.


 38 
 on: April 29, 2025, 23:01:45 
Started by Chris from Nailsea - Last post by JayMac
I put the shorts on for the first time this year.

And Finn had his cooling mat for the car.

 39 
 on: April 29, 2025, 22:43:23 
Started by Mark A - Last post by stuving
The Times this morning had a quote from "energy bosses" that a "very strong oscillation in the electrical network" led to disconnection from "the European system" - i.e. France. I have not heard that anywhere else, so either the Times is very good at digging out sources, or it's wrong. Since it's what such bosses would have said if asked in advance what was the most likely cause of a hypothetical transmission grid collapse, perhaps it was basically a guess - by someone.

At a more recent press conference, the start of the collapse was said to be the disconnection of five (I think) nuclear generators, supplying more than half of of the demand at the time. Now, something must have caused that, and oscillation (instability) fits that bill. After that, total collapse was almost inevitable - it could only be avoided if the links from France (and Morocco, much smaller) could supply most of that deficit (15 GW» (Great Western - used as an abbreviation for the area / lines under the Great Western franchise, as opposed to FGW which includes "First", the company operating them too. For tickets - about)), which sounds pretty unlikely.

Those links from outside all overloaded and tripped, though for the south-west of France the split was within France. They had to break the connection at the Pyrenees before resupplying from the French aside. The powering up of Iberia was done starting from the areas that could be supplied from abroad, in he north and south.

That sounds like the process I would expect to see. Starting the generators in a grid involves them following a grid already supplying power, so that was done using the external links. As much of the grid as could be supplied by those infeeds, at the north and south, was turned on and the generators in that area started up. That gives enough surplus power to prime the next areas and get them going.

 40 
 on: April 29, 2025, 21:23:38 
Started by RailCornwall - Last post by Mark A
An on-the-ground account on this Substack blog. The conflict really is dismal.

Mark


https://martinrobbins.substack.com/p/i-visit-britains-most-expensive-farm

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