Yes I suppose ‘they’ would definitely include a load of NR caution as well. Am I right in recalling that units such as 458s were tested between Dorchester and Weymouth, even though it wasn’t their natural habitat, because the descent into Weymouth allowed for a significant amount of braking, and that part of the route could also be easily isolated from the rest of the network?
I suspect that if regen had been allowed at the time, the power supply upgrades for the new units would have cost a fair bit less.
Correct
Your trustworthy Stadler vehicle will reduce the power if the voltage in the overhead line drops too low.
It was upgraded to 750V DC for Eurostar trains. The main constraint was 4 SUB units which were designed for 660V.
When was the line upgraded on the cheap?
The 2016 EDP specifically states that the increase from 660V to 750V was still in progress in Wessex inner area at that time, especially in the Wimbledon and Richmond areas. I suggest the upgrade for Eurostar was only on specific route sections.
There may have been an island at Richmond and Wimbledon to cover the D78's but it was regraded out from those locations to 750V in the late 80's.
I think I remember reading something about it back in Network SouthEast days. Especially the signalling was done on the cheap, I think. I may be wrong though!
BR did the best with the money it had and did indeed resignal the whole line but back then its was largely operating against falling or at best static traffic levels. To my mind what they did was protect the asset for future generations and if that now needs upgrading to meet increased traffic levels thats to be celebrated.
I'm sure it does but the limiting factor is probably always the throat at terminus stations anyway, of which at any point in the day likelihood is some trains are coming in and some are heading off. You might have 20 platforms but I'll bet you'll only have a maximum of 8 tracks in and out, of course that assumes each departure is perfect from a platform to the track it's going out on and no conflicts
In London area the primary supply voltage for public distribution is 66kV and connections were made from New Cross Grid to four locations in SE London equipped with 66/33kV transformers as 33kV was the standard distribution voltage adopted by BR SR. All other grid points were connected at 33kV. In the 1980's 3rd rail extensions 11kV was used for economic reason for lineside distribution to substations but the grid connections were still at 33kV. Tonbridge to Redhill and West London Line electrifications used 22kV to reflect the higher loads of the Eurostar and CL92 but again connected to the grid at 33kV. As an aside CEGB wouldn't permit connection of traction loads at any lower voltage due to the harmonics that rectifiers produce.
Thanks for the extra detail.
That is generally true, but I mentioned the ECML incident a few posts back. In that case it looks like a blockage was cleared and all the trains queuing behind started away one after the other. Hence there would be several trains running at reasonable speeds but also accelerating, which is the operating mode that draws most power. I don't know if this might be an area where power is marginal - certainly upgrades have been done on the ECML to cope with more frequent electric trains.
So under those 'ECML circumstances', would control advise those trains to accelerate using a lower setting until traffic operation is nearer normal to avoid any undervoltage or overcurrent tripping or just keep their fingers crossed? Also are any precautions taken with the more vulnerable 3rd rail supplies?
OK thanks, - it's reassuring that steps are taken to mitigate a poor supply situation.
