While doing a bit of idle research into the upcoming Standard Stock
(aka 'S' Stock) being designed for the Underground's Sub Surface Lines,
I came across an interesting note which stated that regenerative
braking is to be provided and used by the S stock on the SSL lines, and
_only_ on the SSL lines - the S stock running District Line services to
Richmond and Wimbledon will not regenerate when they are on NR metals.

I'm guessing that the trains will achieve this by using some kind of
mechanism which can detect the voltage level of the negative pole of
the traction circuit and subsequently cut in the regen mechanism when
the negative pole is within the appropriate voltage range. Does anyone
know how this could be accomplished?

TheOneKEA wrote:
I'm guessing that the trains will achieve this by using some kind of
mechanism which can detect the voltage level of the negative pole of
the traction circuit and subsequently cut in the regen mechanism when
the negative pole is within the appropriate voltage range. Does anyone
know how this could be accomplished?

Roger Ford, probably.
--
gordon

On Mon, 13 Nov 2006, TheOneKEA wrote:

While doing a bit of idle research into the upcoming Standard Stock (aka
'S' Stock) being designed for the Underground's Sub Surface Lines, I
came across an interesting note which stated that regenerative braking
is to be provided and used by the S stock on the SSL lines,

At last!

and _only_ on the SSL lines - the S stock running District Line services
to Richmond and Wimbledon will not regenerate when they are on NR
metals.

ISTR a Doctor Who season finale along much the same lines.

Sorry.

I'm guessing that the trains will achieve this by using some kind of
mechanism which can detect the voltage level of the negative pole of the
traction circuit and subsequently cut in the regen mechanism when the
negative pole is within the appropriate voltage range. Does anyone know
how this could be accomplished?

Using the running rails as a voltage reference would be the obvious way to
do it. AIUI, there is a voltage across them from track circuits, but it's
small enough that it shouldn't matter.

However, i wouldn't be at all surprised if the way it actually worked was
that the driver had to flip a switch to turn the regenerator off!

tom

--
Osteoclasts = monsters from the DEEP -- Andrew

Manual switching is not fast enough - regen was always a problem on LUL due
to conductor rail gaps and no through train power bus being allowed.

It has become viable with solid state switching which is fast enough to
detect the gap and virtually instantaneously divert the current to braking
resistors, etc on the train (temporary loss of braking would be undesirable,
at the least!).

Taking this a stage further it would be relatively straightforward to detect
whether the negative rail is at LUL type potential (i.e truly a negative
rail) or at earth potential as on NR tracks. I don't know if this is the
way it is going to be done, but is certainly feasible.

Peter

PS I presume that regen will not be allowed on NR sections due to the
potentially enhanced performance of "conventional" NR stock in the section
when regen is taking place.
--
Peter & Elizabeth Corser
Leighton Buzzard, UK
"Tom Anderson" wrote in message
h.li...
On Mon, 13 Nov 2006, TheOneKEA wrote:

While doing a bit of idle research into the upcoming Standard Stock (aka
'S' Stock) being designed for the Underground's Sub Surface Lines, I came
across an interesting note which stated that regenerative braking is to
be provided and used by the S stock on the SSL lines,

At last!

and _only_ on the SSL lines - the S stock running District Line services
to Richmond and Wimbledon will not regenerate when they are on NR metals.

ISTR a Doctor Who season finale along much the same lines.

Sorry.

I'm guessing that the trains will achieve this by using some kind of
mechanism which can detect the voltage level of the negative pole of the
traction circuit and subsequently cut in the regen mechanism when the
negative pole is within the appropriate voltage range. Does anyone know
how this could be accomplished?

Using the running rails as a voltage reference would be the obvious way to
do it. AIUI, there is a voltage across them from track circuits, but it's
small enough that it shouldn't matter.

However, i wouldn't be at all surprised if the way it actually worked was
that the driver had to flip a switch to turn the regenerator off!

tom

--
Osteoclasts = monsters from the DEEP -- Andrew




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"Peter Corser" wrote in message
...
Manual switching is not fast enough - regen was always a problem on LUL
due to conductor rail gaps and no through train power bus being allowed.

It has become viable with solid state switching which is fast enough to
detect the gap and virtually instantaneously divert the current to braking
resistors, etc on the train (temporary loss of braking would be
undesirable, at the least!).

Taking this a stage further it would be relatively straightforward to
detect whether the negative rail is at LUL type potential (i.e truly a
negative rail) or at earth potential as on NR tracks. I don't know if
this is the way it is going to be done, but is certainly feasible.

Peter

PS I presume that regen will not be allowed on NR sections due to the
potentially enhanced performance of "conventional" NR stock in the section
when regen is taking place.
--
Peter & Elizabeth Corser
Leighton Buzzard, UK

The track power supplies have to be able to accept regeneration without
identifying it as a fault, i.e. transfer the incoming power to elsewhere in
the system with a demand. The system nominal voltage shouldn't rise
significantly. A lot of NR stock is capable of regeneration, but it is the
infrastructure that limits its use. I doubt this applies to the old wrecks
that meet LU at Richmond/Gunnersbury though...

Paul

Tom Anderson wrote:
snip
Using the running rails as a voltage reference would be the obvious
way to do it. AIUI, there is a voltage across them from track
circuits, but it's small enough that it shouldn't matter.


When the train is there the running rails are at the same potential, the
train axles providing the short circuit between them.


--
Cheers for now,

John from Harrow, Middx

remove spamnocars to reply

In article . com,
(TheOneKEA) wrote:

While doing a bit of idle research into the upcoming Standard Stock
(aka 'S' Stock) being designed for the Underground's Sub Surface
Lines, I came across an interesting note which stated that regenerative
braking is to be provided and used by the S stock on the SSL lines,
and _only_ on the SSL lines - the S stock running District Line
services to Richmond and Wimbledon will not regenerate when they are
on NR metals.

I'm guessing that the trains will achieve this by using some kind of
mechanism which can detect the voltage level of the negative pole of
the traction circuit and subsequently cut in the regen mechanism
when the negative pole is within the appropriate voltage range. Does
anyone know how this could be accomplished?

How modern! The O Stock of 1937 was designed for regeneration!

There's no reason in principle why the trains shouldn't use regeneration
on NR too. It will just need modifications to the power supply system. I
hope they get on and make them so that the trains' energy consumption is
reduced.

--
Colin Rosenstiel

On Tue, 14 Nov 2006, John Shelley wrote:

Tom Anderson wrote:

Using the running rails as a voltage reference would be the obvious way
to do it. AIUI, there is a voltage across them from track circuits, but
it's small enough that it shouldn't matter.

When the train is there the running rails are at the same potential, the
train axles providing the short circuit between them.

Doh! Of course.

tom

--
Come on thunder; come on thunder.

On Tue, 14 Nov 2006, Peter Corser wrote:

PS I presume that regen will not be allowed on NR sections due to the
potentially enhanced performance of "conventional" NR stock in the
section when regen is taking place.

That would be highly entertaining. Extremely dangerous, but entertaining!

tom

--
Come on thunder; come on thunder.

Colin

The O stock used metadyne control with the regen being part of a closed loop
control system - IIRC (need to check "Steam to Silver"!) there was no regen
to the rails, as such.

Peter
--
Peter & Elizabeth Corser
Leighton Buzzard, UK
"Colin Rosenstiel" wrote in message
...
In article . com,
(TheOneKEA) wrote:

While doing a bit of idle research into the upcoming Standard Stock
(aka 'S' Stock) being designed for the Underground's Sub Surface
Lines, I came across an interesting note which stated that regenerative
braking is to be provided and used by the S stock on the SSL lines,
and _only_ on the SSL lines - the S stock running District Line
services to Richmond and Wimbledon will not regenerate when they are
on NR metals.

I'm guessing that the trains will achieve this by using some kind of
mechanism which can detect the voltage level of the negative pole of
the traction circuit and subsequently cut in the regen mechanism
when the negative pole is within the appropriate voltage range. Does
anyone know how this could be accomplished?

How modern! The O Stock of 1937 was designed for regeneration!

There's no reason in principle why the trains shouldn't use regeneration
on NR too. It will just need modifications to the power supply system. I
hope they get on and make them so that the trains' energy consumption is
reduced.

--
Colin Rosenstiel



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