On Jan 17, 1:48 pm, John B wrote:

TSO and PTSO really ought to give you a clue before looking at the
weights !

OTOH, 10 tonnes seems a bit heavy-duty for a pantograph. Is it an SNCF
design...?

I'm trying to think of exceptions - but AFAIK PTSO in EMU usually
means transformer as well as pantograph .... becuase if it does not
mean that then there is a 25 kV bus line between cars ... see
uk.railway previous yawns.

--
Nick

On Thu, 17 Jan 2008 13:48:40 -0800 (PST), John B
wrote:

On 17 Jan, 21:39, D7666 wrote:
have a PTSO 10t heavier than
the DC versions TSO,

;o)

TSO and PTSO really ought to give you a clue before looking at the
weights !

;o)

OTOH, 10 tonnes seems a bit heavy-duty for a pantograph. Is it an SNCF
design...?

The transformer is also on that vehicle, if applicable, and the steel
core of those isn't exactly lightweight.

Neil

--
Neil Williams
Put my first name before the at to reply.

On 17 Jan, 22:02, D7666 wrote:
TSO and PTSO really ought to give you a clue before looking at the
weights !
OTOH, 10 tonnes seems a bit heavy-duty for a pantograph. Is it an SNCF
design...?

I'm trying to think of exceptions - but AFAIK PTSO in EMU usually
means transformer as well as pantograph .... becuase if it does not
mean that then there is a 25 kV bus line between cars ... see
uk.railway previous yawns.

Yup, I figured. 10 tonnes seems pretty damn heavy even for a 1550kW
transformer, but IANAMIEEE...

--
John Band
john at johnband dot org
www.johnband.org

"Boltar" wrote:

Why do the trains on the NLL switch over to 25Kv AC at Hackney Wick
and then switch back to DC at Dalston when the 3rd rail is continuous
along that section anyway? Why not just stay on DC and save the wear
and tear on the pantograph?

Because the DC supply in that area is somewhat constrained, and only allows
a limited number of simultaneous train movements.*

No time to check, but I believe the NLL timetable is more intensive than
when that section was first used by the 2-EPBs.

Chris

* So says Mr Rob Curling on Video 125's 'North London Line Drivers Eye
View'.

On Thu, 17 Jan 2008 22:22:08 -0000, "Chris Read"
wrote:


"Boltar" wrote:

Why do the trains on the NLL switch over to 25Kv AC at Hackney Wick
and then switch back to DC at Dalston when the 3rd rail is continuous
along that section anyway? Why not just stay on DC and save the wear
and tear on the pantograph?

Because the DC supply in that area is somewhat constrained, and only allows
a limited number of simultaneous train movements.*

No time to check, but I believe the NLL timetable is more intensive than
when that section was first used by the 2-EPBs.

Chris

* So says Mr Rob Curling on Video 125's 'North London Line Drivers Eye
View'.

The problem seems to be with the type of loading that 313s cause on
the DC supplies. In the early 1960s parts of the DC line had a 2 - 2.5
minute headway (back of envelope calculation gives about 2 Bakerloo
trains and 4 6-coach BR/LMS trains taking power) and the substations
coped with that but when cl501s were replaced with 313s they were
unable to run as 6-coach as they tripped out the sub-stations when
moving off.

various snipped out

I don't know what the current limit relays were set at on 501s but
being 4 motors per unit would be likely to draw more than a two motor
2EPB.

Published ''spotting book'' values of a 2EPB are 2x250 hp and 501
4x185 hp so that makes a 501 in round figures 50% more powerful than a
2EPB - but I'd caution those numbers with similar comments I have made
before about DC EMU in that the current limit relay setting needs to
be known to understand peak current draw.

As regards another part of the thread, I thought 2x313 operation was
killed by platform length limits. 501 units were on 57 foot frames
and platforms that could take 6cars laid out for that length - but
could not take standard 6car sliding door trains with 20 m bodies.

And I can't see why a 6car 313 would draw siginficantly more power
than a 6car 501 to trip traction supplies. Again using ''spotting
book'' values, without current limit values, a 313 has 8x82 kW motors
that in round figures is 880 hp per unit - while a 501 is 740 hp.

I would have expected the LNWR DC supply to have been a bit more
robust than that as the overall load increase taking all traffic is
not 20% from a simple 313 and 501 comparison - but is Bakerloo+501
c.f. Bakerloo+313 with the Bakerloo load unchanged.

Must admit never thought about this aspect before, I might be wrong,
its not a route thats easy to obtain gen on the traction supplies.

--
Nick

On Thu, 17 Jan 2008, D7666 wrote:

On Jan 17, 1:32 pm, "Paul Scott"
wrote:

have a PTSO 10t heavier than the DC versions TSO,

;o)

TSO and PTSO really ought to give you a clue before looking at the
weights !

;o)

*scratches head*

http://www.abrail.co.uk/coachcodedetail.htm

Aha!

tom

--
It's just really ****ing good and that's all. -- Gabe, on the Macintosh

On Thu, 17 Jan 2008 23:13:08 +0000, Charles Ellson wrote:

The problem seems to be with the type of loading that 313s cause on
the DC supplies. In the early 1960s parts of the DC line had a 2 - 2.5
minute headway (back of envelope calculation gives about 2 Bakerloo
trains and 4 6-coach BR/LMS trains taking power) and the substations
coped with that but when cl501s were replaced with 313s they were
unable to run as 6-coach as they tripped out the sub-stations when
moving off.

Interesting, especially considering the line is fitted with (IIRC
Silverlink-style) "6 car stop" signs.

On Thu, 17 Jan 2008 19:55:22 +0000 someone who may be Tom Anderson
wrote this:-

Or do modern DC trains work by inverting the DC
into a low-voltage AC at the same frequency as an OHLE supply and using
that to work a motor?

In general a system takes low voltage DC from the supply (the
conductor rail) and inverts it to low voltage AC at variable
frequency, to operate the motors. The system will have a range of
input voltages.

To produce an AC version a transformer and rectifier convert the
supply to a DC voltage in the input voltage range.

This double conversion sounds odd to people of an earlier
generation, but the many advantages outweigh the small
disadvantages.


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

Does anyone know how many, if any. of the original LNWR sub-stations
are still in use? There are various large buildings adjacent to the
NLL/Euston DC Lines which seem to foor the bill but others have
disappeared. The one visible on the NLL from the Met/Jubilee Lines has
gone, as has another large structure which stood near East Putney on
the EN side. Is the large building on the WCML side in the Kenton/
Northwick Park area a former LNWR sub?