I read about this in wikipedia but is it actually going to happen? If so what
will happen on sections where tube and sub surface stock run on the same track
- ie raynors lane to uxbridge and acton town to ealing common. Will these
sections be kept at 630V or will the piccadilly stock be able to handle 750V
anyway?

B2003

d wrote:
I read about this in wikipedia but is it actually going to happen? If
so what will happen on sections where tube and sub surface stock run
on the same track - ie raynors lane to uxbridge and acton town to
ealing common. Will these sections be kept at 630V or will the
piccadilly stock be able to handle 750V anyway?

There is definitely a power supply upgrade going on, just announced he

http://www.tfl.gov.uk/corporate/medi...tre/15249.aspx

but they don't explicitly say they are raising the system voltages - it
wouldn't necessarily follow anyway, the regulated voltage could stay the
same but with a higher current draw being allowed.

Related to this, there are apparently Network Rail projects going on at the
moment to separate out all the mainline and 'tube' supplies where they are
connected, to allow the NR third rail voltage to be raised to a standard 750
volts, and to allow regenerative braking. An example is the Waterloo and
City, still fed off the SR for obvious historic reasons.

What I'm wondering is that if LU adopted a 750 volt standard on the SSR, NR
wouldn't necessarily need to do this - unless they want to have separate
billing anyway - there's also practicalities such as isolations for
maintenance.

Paul S

On Mon, 12 Apr 2010 14:50:26 +0100
"Paul Scott" wrote:
http://www.tfl.gov.uk/corporate/medi...tre/15249.aspx

but they don't explicitly say they are raising the system voltages - it
wouldn't necessarily follow anyway, the regulated voltage could stay the
same but with a higher current draw being allowed.

Raising the voltage does seem an odd thing to do not least because they dropped
the voltage from 640V years ago citing power saving reasons (which sounds like
rubbish TBH , lower voltages are less efficient , not more).

B2003

On 12/04/2010 14:56, d wrote:

Raising the voltage does seem an odd thing to do not least because they dropped
the voltage from 640V years ago citing power saving reasons (which sounds like
rubbish TBH , lower voltages are less efficient , not more).

.... unless the lower voltages leak less.

Basil Jet wrote:
On 12/04/2010 14:56, d wrote:

Raising the voltage does seem an odd thing to do not least because
they dropped
the voltage from 640V years ago citing power saving reasons (which
sounds like
rubbish TBH , lower voltages are less efficient , not more).

... unless the lower voltages leak less.

Lower voltage means a higher current draw for the same power, and
transmission losses are proportional to I^2.

Rgds

Denis McMahon

"Paul Scott" wrote in message
...
d wrote:
I read about this in wikipedia but is it actually going to happen? If
so what will happen on sections where tube and sub surface stock run
on the same track - ie raynors lane to uxbridge and acton town to
ealing common. Will these sections be kept at 630V or will the
piccadilly stock be able to handle 750V anyway?

There is definitely a power supply upgrade going on, just announced he

http://www.tfl.gov.uk/corporate/medi...tre/15249.aspx

but they don't explicitly say they are raising the system voltages - it
wouldn't necessarily follow anyway, the regulated voltage could stay the
same but with a higher current draw being allowed.

Related to this, there are apparently Network Rail projects going on at
the moment to separate out all the mainline and 'tube' supplies where they
are connected, to allow the NR third rail voltage to be raised to a
standard 750 volts, and to allow regenerative braking. An example is the
Waterloo and City, still fed off the SR for obvious historic reasons.

What I'm wondering is that if LU adopted a 750 volt standard on the SSR,
NR wouldn't necessarily need to do this - unless they want to have
separate billing anyway - there's also practicalities such as isolations
for maintenance.

Paul S

The Central Line is already 750V - it was converted with the last upgrade.

There is still a difference between nominal voltages on LUL (4 rail) & NR (3
rail).

Peter
--
Peter & Elizabeth Corser
Leighton Buzzard, UK

On Mon, 12 Apr 2010 14:57:36 +0100
"Peter Corser" wrote:
The Central Line is already 750V - it was converted with the last upgrade.

Does that mean the western central line can't be used for stock moves any
more except for 92 stock?

B2003

On 12 Apr, 15:28, wrote:
On Mon, 12 Apr 2010 14:57:36 +0100

"Peter Corser" wrote:
The Central Line is already 750V - it was converted with the last upgrade.

Does that mean the western central line can't be used for stock moves any
more except for 92 stock?

B2003

Doesn't Bakerloo tube stock run on 750 V beyond Queens Park?

On Mon, 12 Apr 2010 08:20:25 -0700 (PDT), MIG
wrote:

On 12 Apr, 15:28, wrote:
On Mon, 12 Apr 2010 14:57:36 +0100

"Peter Corser" wrote:
The Central Line is already 750V - it was converted with the last upgrade.

Does that mean the western central line can't be used for stock moves any
more except for 92 stock?

B2003

Doesn't Bakerloo tube stock run on 750 V beyond Queens Park?

According to :-
http://www.statemaster.com/encyclope...-Great-Britain

the DC line is 650v which ISTR has been stencilled on many trackside
cabinets for years. OTOH the native trains have been able to run on
750v since at least the c.501 if not also the immediately preceding
LMS trains. ATM there doesn't seem to be an "official" confirmation
which leaps to the front of the Google queue.

On Apr 12, 2:57*pm, "Peter Corser"
wrote:

The Central Line is already 750V - it was converted with the last upgrade..


Was it ?

Not according to what I see , and what I have checked on, today, with
the DC traction SCADA indicating line wide values fluctuating around
620 +/- 10 V ... that suggests its 630 V

--
Nick