ukclique > railway

jack (13.09.2017, 14:08)
On Wednesday, 13 September 2017 06:49:32 UTC+1, Roland Perry wrote:
> In message <6dpgrctbuvn4djdkdquu117ahbtcg4cd5n>, at 00:13:25 on
> Wed, 13 Sep 2017, David C <jf> remarked:
> There was a changeover from 6.25 to 25kV somewhere on the Shenfield line
> - you could hear the enormous bang if you were sat in the panto car.


Was that necessarily a voltage change though, you also got an
enormous bang at neutral sections as the breaker opened and
closed again, controlled by track-side magnets. Drivers
were supposed to shut off power when passing through neutral
sections but there was one near Bishipton that was sometimes
taken under full power by the only down train of the day which
didn't stop (istr the 17:30 from Glasgow), with fairly
spectacular results as the roof-mounted breaker on the
power car opened and showers of sparks cascaded down the
sides of the train.
Roland Perry (13.09.2017, 14:24)
In message <fd0a983d-7500-4d3b-a6d3-122f1c8f3503>, at
05:08:47 on Wed, 13 Sep 2017, jack remarked:

>> There was a changeover from 6.25 to 25kV somewhere on the Shenfield line
>> - you could hear the enormous bang if you were sat in the panto car.

>Was that necessarily a voltage change though,


That's my understanding, yes. Unless of course that was the only neutral
section between LST and Chelmsford, which I doubt.
Graeme Wall (13.09.2017, 18:20)
On 13/09/2017 10:04, spud wrote:
> On Wed, 13 Sep 2017 09:00:53 +0100
> "Peter Able" <stuck> wrote:
> Only if no increase in the vertical loading gauge is ever planned to occur
> in the future, eg for double deck trains.


Unlikely to ever happen on classic lines and new build, eg HS2, will,
presumably, be higher to start with.
Peter Able (13.09.2017, 20:18)
"Chris J Dixon" <chris> wrote in message
news:0d2e
> Peter Able wrote:
> One of my first tasks at what was then GEC was producing the mod
> instructions for adding "Wrong Voltage Selection Protection" to
> the Class 312, which were in build at the time.
> It was certainly all quite complex, and I think the mod was to
> prevent the kit deciding, as the pan rose and an arc was drawn,
> to select the 6.25 kV mode just as the full 25 kV appeared, with
> consequent problems.
> Chris


That fits the official documentation, Chris

"The circuit is arranged to prevent the voltage changeover switch operating
in the event of a fault on the 25 kV system lowering the voltage temporarily
to within the 3.5/6.9 zone."

Best day's work some committee did was to consign 6.25kV to the bin, though.
The safest mod you can work up is the one you can eliminate the need for!

PA
Chris J Dixon (13.09.2017, 20:59)
Peter Able wrote:

[..]
>conjunction with track magnet detectors - plus a feature that I haven't
>fully analysed which was supposed to stop momentary dips in the 25kV voltage
>from making the relays switch into 6.25kV mode.


One of my first tasks at what was then GEC was producing the mod
instructions for adding "Wrong Voltage Selection Protection" to
the Class 312, which were in build at the time.

It was certainly all quite complex, and I think the mod was to
prevent the kit deciding, as the pan rose and an arc was drawn,
to select the 6.25 kV mode just as the full 25 kV appeared, with
consequent problems.

Chris
Recliner (13.09.2017, 22:45)
On Wed, 13 Sep 2017 17:20:07 +0100, Graeme Wall
<rail> wrote:

>On 13/09/2017 10:04, spud wrote:
>Unlikely to ever happen on classic lines and new build, eg HS2, will,
>presumably, be higher to start with.


Yes, it's being built large enough to take continental high speed
stock, although the initial fleet will all be UK classic-compatible.
However, I don't think it'll be built wide enough for Japanese
full-size Shinkansen stock (in one model of which ordinary class pax
travel in 3+3 seating on the lower deck of a double-decker).
Graeme Wall (13.09.2017, 23:00)
On 13/09/2017 21:45, Recliner wrote:
> On Wed, 13 Sep 2017 17:20:07 +0100, Graeme Wall
> <rail> wrote:
> Yes, it's being built large enough to take continental high speed
> stock, although the initial fleet will all be UK classic-compatible.
> However, I don't think it'll be built wide enough for Japanese
> full-size Shinkansen stock (in one model of which ordinary class pax
> travel in 3+3 seating on the lower deck of a double-decker).


I think the chance of through trains working from Tokyo to London is
unlikely to happen in my lifetime though I understand at least one
person is working on a similar project for this country :-)
Recliner (13.09.2017, 23:21)
On Wed, 13 Sep 2017 22:00:21 +0100, Graeme Wall
<rail> wrote:

>On 13/09/2017 21:45, Recliner wrote:
>I think the chance of through trains working from Tokyo to London is
>unlikely to happen in my lifetime though I understand at least one
>person is working on a similar project for this country :-)


Not for through working, which isn't planned (or possible) even from
France, but for the freedom to buy off-the-shelf high speed stock from
anywhere.

Unfortunately, even the largest Shinkansens aren't compatible with the
minimum requirements for RingbyRail.
spud (14.09.2017, 10:39)
On Wed, 13 Sep 2017 21:45:18 +0100
Recliner <Recliner.ng> wrote:
>On Wed, 13 Sep 2017 17:20:07 +0100, Graeme Wall
><rail> wrote:
>Yes, it's being built large enough to take continental high speed
>stock, although the initial fleet will all be UK classic-compatible.
>However, I don't think it'll be built wide enough for Japanese
>full-size Shinkansen stock (in one model of which ordinary class pax
>travel in 3+3 seating on the lower deck of a double-decker).


Pity really. Interoperability is overrated IMO if the trains are almost
never going to leave their dedicated lines. Its hardly unprecedented to have
trains who can't leave their route due to loading gauge in the UK either, eg on
the tube and the channel tunnel vehicle wagons.

UK stock and even a lot of EU stock is too narrow to be properly comfortable
in anything but 2+2 layout and even thats pushing it on some trains IMO.
Clive D.W. Feather (14.09.2017, 11:47)
In article <v03FQtxVYMuZFAZ4>, Roland Perry
<roland> writes
>There was a changeover from 6.25 to 25kV somewhere on the Shenfield line
>- you could hear the enormous bang if you were sat in the panto car.
>While my memory says it was perhaps closer the Liverpool St, common
>sense says it might have been the country side of Gidea Park (which was
>a major turn-back station for inner suburbans comprising rather old
>stock).


The bangs were for neutral sections whether or not they involved a
voltage change. I can remember them on 312s on the ECML.

Wikipedia says:

> The line from Liverpool Street to Southend Victoria was originally
> electrified at 1,500 V DC overhead during the 1940s-50s. During the
> early 1960s, the whole of this line was converted to 6.25 kV AC
> overhead, while the main line east of Shenfield was progressively
> electrified at 25 kV, with changeover east of Shenfield. During the
> early 1980s, the line was again converted, this time to 25 kV.


> The Cambridge line and branches from Liverpool Street was electrified
> in the early 1960s, with 6.25 kV out to a changeover at Cheshunt, and
> 25 kV beyond. The Chingford and Enfield lines were thus at 6.25 kV
> throughout. This route was again fully converted to 25 kV in the early
> 1980s.


My memory of 1980 or so is that there was a changeover point in Greater
London on the GEML, but I couldn't say where. I remember reports in the
various magazines of the point moving towards Liverpool Street over the
years.

(I've just remembered that I have some stuff at home that will answer
this. Unfortunately I'm in Washington state.)
jb (16.09.2017, 17:45)
On Wednesday, 13 September 2017 10:44:10 UTC+1, BirchangerKen wrote:
> On Wed, 13 Sep 2017 00:13:25 +0100, David C <jf> wrote:
> Once the Lea Valley line was electrified a further changeover would
> have been needed, as 'between Edmonton and Cheshunt' is on the
> Southbury loop. Where was it? I thought, from my vague recollection of
> the publicity when the 6.25kV stuff was converted to 25kV, that it was
> close to Clapton, but if the entire Chingford line was at 6.25kV then
> it must have been further north. Coppermills?


I'm 99% certain that the changeover was between Clapton Junction and Coppermill Junction. The voltage changeover neutral section was converted to an ordinary neutral section - it is at 4m 66ch according to the Sectional Appendix.
R. Mark Clayton (16.09.2017, 21:54)
On Tuesday, 12 September 2017 18:11:29 UTC+1, Scott wrote:
> On Tue, 12 Sep 2017 05:48:04 -0700 (PDT), "R. Mark Clayton"
> <notyalckram> wrote:
> Was this in the days of 6.25kV?


Don't when that was, I think it referred to when Euston to Glasgow was finally electrified (25kV all the way AFAIK). Pre 1981 if that helps.
Christopher A. Lee (16.09.2017, 22:43)
On Sat, 16 Sep 2017 12:54:47 -0700 (PDT), "R. Mark Clayton"
<notyalckram> wrote:

>On Tuesday, 12 September 2017 18:11:29 UTC+1, Scott wrote:
>Don't when that was, I think it referred to when Euston to Glasgow was finally
>electrified (25kV all the way AFAIK). Pre 1981 if that helps.


South of Crewe was all 25KvAC in the 1960s, when they started reducing
clearences.

Hence the yellow stripe on the cabs of steam locomotives to say they
were prohibited.
Scott (17.09.2017, 20:20)
On Wed, 13 Sep 2017 17:20:07 +0100, Graeme Wall
<rail> wrote:

>On 13/09/2017 10:04, spud wrote:
>Unlikely to ever happen on classic lines and new build, eg HS2, will,
>presumably, be higher to start with.


Even more unlikely through Glasgow Central Low Level :-)

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