Mid voltage AC would probably have many attractions. Suggest 625/1250/2500
respectively for underground, inner urban and open country respectively.
Dual voltage with 25kV relatively easy to do.


DW

"Cast_Iron" wrote in message
...
: Boltar wrote:
: are (Acrosticus) wrote in message
: ...
: From: Michael Bell
: Date: 08/08/2003 23:43 GMT Daylight Time
:
: It has always seemed to me that the 750 volt 3rd rail is
: a bad
: idea.
:
: Too right! Massive amperages, high resistances, huge
: numbers of substations in
: relation to the length of a line. It's an idea that's
: really past its sell by
: date. If you want to electrify, do it properly with 25Kv
: at 50 Hertz in a wire
: up on some sticks. Tinkering about with 750v DC is about
: as much good as
: rearranging the deckchairs on the deck of the "Titanic".
:
: OTOH hand , when was the last time that you heard of trains
: being stuck or
: cancelled because the 3rd rail fell over? There doesn't
: seem to be a winter
: that goes by without some AC line being screwed by snapped
: overhead wires.
: Catenary is fragile and flakey and is a terrible design
: plus it looks bloody
: awful too. The only place its really needed is street based
: tramways.
:
: What is needed is some sort of mid voltage (maybe
: 3000-6000V) sturdy ground
: based 3rd rail system which isn't as fragile as overhead
: wires but doesn't
: have the power losses of standard 750V 3rd rail. I'm sure
: isn't beyond the wit
: of man to devise it.
:
: Probably incredibly easy to devise, but paying for it - now that's the
: difficult one to organise.
:
: