On Wed, 12 Aug 2009 09:32:22 +0100
"Colin McKenzie" wrote:
Technology moves on. Even if it didn't, priorities would.

For example, low energy consumption should be given much higher priority
now than it was in the 95/6 stock.

If low energy consumption is a priority now (why it wouldn't have been in 1995
I don't know but anyway..) why are LUL having to upgrade the power supply on
the victoria line to cope with the new 09 stock? I wouldn't call using more
power that the old trains energy efficient would you?

Occasionally a 5-year old design may be the best option, but not often.

Even car designs last longer than 5 years and even then most of the changes
in the new model are cosmetic. What is so radical in train designs that they
must change even more often?

B2003

wrote in message
On Wed, 12 Aug 2009 09:32:22 +0100
"Colin McKenzie" wrote:
Technology moves on. Even if it didn't, priorities would.

For example, low energy consumption should be given much higher
priority now than it was in the 95/6 stock.

If low energy consumption is a priority now (why it wouldn't have
been in 1995 I don't know but anyway..) why are LUL having to upgrade
the power supply on the victoria line to cope with the new 09 stock?
I wouldn't call using more power that the old trains energy efficient
would you?

True, but the new Victoria line trains are longer, faster and more
frequent, so that may account for some of the extra power.


Occasionally a 5-year old design may be the best option, but not
often.

Even car designs last longer than 5 years and even then most of the
changes in the new model are cosmetic. What is so radical in train
designs that they must change even more often?

Cars typically have an eight year production life, but the technology is
often updated during that time. Right now, most new cars are markedly
more fuel efficient than their predecessors, so there really are major
technology changes happening. For example, engines themselves are
cleaner and more economical, they may shut down when the car is stopped,
they may only power the alternator when the car is not accelerating,
etc. And there's lots more to come.

I don't see why trains shouldn't also get significantly more efficient,
more comfortable and more reliable over time (though, of course,
sometimes they get worse, like the 1983 stock, which was the last
LU-designed train).

On Wed, 12 Aug 2009 10:26:30 +0100
"Recliner" wrote:
True, but the new Victoria line trains are longer, faster and more
frequent, so that may account for some of the extra power.

I suppose.

I don't see why trains shouldn't also get significantly more efficient,
more comfortable and more reliable over time (though, of course,

I don't know about reliability but there does seem to be a trend of every
new electric train in this country using more power than its predecessor.
In the case of the 377s significantly more. This is in stark contrast to
cars which despite getting heavier year on year are still using less fuel
with each generation. Whatever the train builders are concentrating on in
their designs, energy efficiency doesn't seem to be it.

B2003

wrote in message
On Wed, 12 Aug 2009 10:26:30 +0100
"Recliner" wrote:
True, but the new Victoria line trains are longer, faster and more
frequent, so that may account for some of the extra power.

I suppose.

I don't see why trains shouldn't also get significantly more
efficient, more comfortable and more reliable over time (though, of
course,

I don't know about reliability but there does seem to be a trend of
every new electric train in this country using more power than its
predecessor. In the case of the 377s significantly more. This is in
stark contrast to cars which despite getting heavier year on year are
still using less fuel with each generation. Whatever the train
builders are concentrating on in their designs, energy efficiency
doesn't seem to be it.

That does indeed seems to have been the trend until recently, but I
think they're now getting the message.

For example, after Captain Deltic described the Desiro as a lardbutt,
Siemens has responded with a new lightweight Desiro City train. It
claims that, "The lightweight design of the train and the bogies
combined with an intelligent vehicle control system reduce overall
energy consumption by up to 50 per cent compared to preceding models."
http://w1.siemens.com/press/en/pressrelease/?press=/en/pressrelease/2009/mobility/imo20090736.htm

Recliner wrote:


For example, after Captain Deltic described the Desiro as a lardbutt,
Siemens has responded with a new lightweight Desiro City train. It
claims that, "The lightweight design of the train and the bogies
combined with an intelligent vehicle control system reduce overall
energy consumption by up to 50 per cent compared to preceding models."
http://w1.siemens.com/press/en/pressrelease/?press=/en/pressrelease/2009/mobility/imo20090736.htm


Don't forget upgrading the power supply to cope with regen braking and
the likely differences in power consumption curves between 1960s and
2000s era motors, as detailed in Cap'n D's Southern Power Upgrade stuff
a few years back. It's not wholly surprising that a larger fleet of new
trains running more frequently with different motor characteristics and
regen would require a power supply upgrade in tandem.

Tom

In message , at 09:36:19 on Wed, 12 Aug 2009,
remarked:
I don't know about reliability but there does seem to be a trend of every
new electric train in this country using more power than its predecessor.
In the case of the 377s significantly more. This is in stark contrast to
cars which despite getting heavier year on year are still using less fuel
with each generation. Whatever the train builders are concentrating on in
their designs, energy efficiency doesn't seem to be it.

Cars potentially use more and more energy on more and more gadgets just
like trains, but have significantly more efficient engines year on year.
You might be able to apply some of the engine-improvement technology to
DMUs, but can electric motors be made any more efficient?
--
Roland Perry

On Aug 12, 11:14*am, Roland Perry wrote:
You might be able to apply some of the engine-improvement technology to
DMUs, but can electric motors be made any more efficient?

Yes:
1) three-phase induction motors instead of synchronous DC motors
2) regenerative braking

These have been done. This is why overall energy consumption for new
electric trains isn't substantially higher than for older electric
trains, despite their much higher peak power ratings.

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

In message
, at
03:53:07 on Wed, 12 Aug 2009, John B remarked:
You might be able to apply some of the engine-improvement technology to
DMUs, but can electric motors be made any more efficient?

Yes:
1) three-phase induction motors instead of synchronous DC motors
2) regenerative braking

These have been done.

So you can't make them *more* efficient, then (starting today,
obviously).

This is why overall energy consumption for new electric trains isn't
substantially higher than for older electric trains, despite their much
higher peak power ratings.

You seem to be talking about historic improvements which have reached a
plateau.

And a plateau is exactly what car engines have *not* yet reached, and
what the question was effectively about.
--
Roland Perry

"Roland Perry" wrote in message

In message
,
at 03:53:07 on Wed, 12 Aug 2009, John B remarked:
You might be able to apply some of the engine-improvement
technology to DMUs, but can electric motors be made any more
efficient?

Yes:
1) three-phase induction motors instead of synchronous DC motors
2) regenerative braking

These have been done.

So you can't make them *more* efficient, then (starting today,
obviously).

Note the comments I made upthread about the new Desiro City train, of
which the manufacturer says, "The lightweight design of the train and
the bogies combined with an intelligent vehicle control system reduce
overall energy consumption by up to 50 per cent compared to preceding
models." I assume the comparison is with other electric Desiros, such
as the 350s, so it looks like significant further savings are still
available.

However, I think that electric trains are already so efficient that the
amount of improvement available can't be as much as cars, which start
from a much worse position. After all, you can't do as much to improve
the aerodynamics of a train as you can a car, and there isn't an idling
engine you could switch off at stations.

On Aug 12, 10:36*am, wrote:
On Wed, 12 Aug 2009 10:26:30 +0100

"Recliner" wrote:
True, but the new Victoria line trains are longer, faster and more
frequent, so that may account for some of the extra power.

I suppose.

I don't see why trains shouldn't also get significantly more efficient,
more comfortable and more reliable over time (though, of course,

I don't know about reliability but there does seem to be a trend of every
new electric train in this country using more power than its predecessor.
In the case of the 377s significantly more. This is in stark contrast to
cars which despite getting heavier year on year are still using less fuel
with each generation. Whatever the train builders are concentrating on in
their designs, energy efficiency doesn't seem to be it.

No, you're missing the point here. Power isn't the same thing as
energy. Power rating is a peak; energy consumption is an average.

New trains have more efficient motors than older trains [thanks to the
move from DC traction to AC traction], and the weight of the 09 stock
is no higher than the weight of the 1967 stock - but instead of a peak
power rating of 848kW, it has a peak power rating of 1800kW.

That means it accelerates to line speed faster, hence putting more
load on the infrastructure, hence (alongside the regenerative braking
already discussed) the need for the power upgrade.

But it also means that it'll spend less time drawing the peak power
rating, and more time cruising - hence overall energy consumption
won't be higher (OK, there'll slight extra air resistance and friction
from the fact that the train spends more time going faster, but this
will be small, and more than offset by the impact of regen).

With the Mk1 replacements on the Southern, it's a bit more
complicated, as the new trains were heavier and had power doors,
aircon, etc - but again, a lot of the difference was higher peak draw
not higher overall energy consumption.

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