On Jul 24, 11:44*pm, Andy wrote:

No I've not, you've missed mine. You were the one mentioning 3 times
the current draw, when the numbers say less than twice the current
draw.



If the cont power rating of 2009 stock is 1800 kW and the cont power
rating of 1967 sock is 848 kW and they are both drawing that power at
630 V DC then that alone, comparing one 8-car train with another draws
2.12 times as much current from traction DC.

Or are you going to tell me now that the Laws of Ohm, Kirchoff,
Newton, and anyone else with an established theorem of electricity or
mechanics is wrong ?

If not then read on.

Making no changes to the service, across the whole line, its must then
follow as 2.12 times as much current.

But there are 37 trains (I think) in the present timetable. That [I
think] goes to 41 with full 2009 stock service post VUl. That actually
up ~10%. So its 2.33 times the current.

Thats the base load, on cont ratings, before we even look at one hour
or short term overloads.

Those new trains in the full timetable will work harder - instead of
[?] 28 TPH they work 33[??] TPH - so they will be pushed harder with
the new ATO than the old ATO does with 1967 stock. (You only have to
go on the Central Line to see how a more modern ATO system pushes
trains - and that is a system that is very like the one going in on
VUL, just a refined version of it.)

But only constant current whilst the train is actually motoring,

In the same way the 1967 stock don't draw current all the time only
when motoring.

The *relative* load proportion of 1967 and 2009 stock at continuous
rating thus remains at around 2.33 times.

So far I've only looked at traction motor load.

Add air con etc - anyone want to esitimate or state what the aircon
load of 2009 stock is ?

It is around 1 MW on a Eurostar. I'm not seriously suggesting 2009
stock is the same load, but write it as its the only one I know off
the top of my head to show how siginificant these loads are.


That traction load goes on top the 2.33 ... in round figures with
auxiliary load we approach 3x.

--
Nick