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Groups > alt.folklore.computers > #152918

Re: optimum power supply for subway/light rail lines

From Stephen Sprunk <stephen@sprunk.org>
Newsgroups alt.folklore.computers
Subject Re: optimum power supply for subway/light rail lines
Date 2015-10-14 13:15 -0500
Organization A noiseless patient Spider
Message-ID <mvm5vu$qfl$1@dont-email.me> (permalink)
References <5932e6a1-4930-466c-8bb8-4baadf9e9e77@googlegroups.com> <da9d50b2-3ada-45ff-bb1b-ef88ca43d84a@googlegroups.com>

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On 13-Oct-15 00:15, Quadibloc wrote:
> hanc...@bbs.cpcn.com wrote:
>> But should they be AC?
> 
> For them to be DC, the DC would have to be specially created. 600
> volt AC can be produced from what is in transmission lines by the use
> of a transformer.

AC has advantages for distribution, but in modern rail applications, it
has to be rectified anyway, so the question becomes whether it is better
to transform and rectify on lots of trains or in lots of wayside
substations.

For subways and trams, where train density is high and power per train
is low, low-voltage DC has a lower total cost.  For intercity rail,
where train density is low and power per train is high, high-voltage AC
has a lower total cost.  So, that's what you see in practice.

> So I presume that a 600 volt train line doesn't get connected to the
> generating plant at one point - instead, it gets supplied with power
> at locations all over the map, at relatively short intervals of
> distance, from transformers on power poles.

Yes; 600VDC (or 750VDC) requires a substation every couple miles,
depending on train density and speed, and each is independently
connected to the grid.

For historical reasons, some AC systems use 16.7Hz or 25Hz, but all
(AFAIK) new projects are at grid frequency so they can connect each
substation to the grid, as with DC systems, rather than building their
own expensive, redundant distribution networks.

S

-- 
Stephen Sprunk         "God does not play dice."  --Albert Einstein
CCIE #3723         "God is an inveterate gambler, and He throws the
K5SSS        dice at every possible opportunity." --Stephen Hawking

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optimum power supply for subway/light rail lines hancock4@bbs.cpcn.com - 2015-08-24 11:00 -0700
  Re: optimum power supply for subway/light rail lines "hqhy" <hqhy@nospam.com> - 2015-08-25 04:47 +1000
    Re: optimum power supply for subway/light rail lines Stephen Sprunk <stephen@sprunk.org> - 2015-08-24 15:01 -0500
  Re: optimum power supply for subway/light rail lines Stephen Sprunk <stephen@sprunk.org> - 2015-08-24 14:45 -0500
    Re: optimum power supply for subway/light rail lines hancock4@bbs.cpcn.com - 2015-08-24 13:22 -0700
      Re: optimum power supply for subway/light rail lines Stephen Sprunk <stephen@sprunk.org> - 2015-08-25 13:26 -0500
        Re: optimum power supply for subway/light rail lines hancock4@bbs.cpcn.com - 2015-08-25 11:48 -0700
          Re: optimum power supply for subway/light rail lines Stephen Sprunk <stephen@sprunk.org> - 2015-08-25 16:12 -0500
            Re: optimum power supply for subway/light rail lines hancock4@bbs.cpcn.com - 2015-08-25 20:20 -0700
        Re: optimum power supply for subway/light rail lines danny burstein <dannyb@panix.com> - 2015-08-25 20:28 +0000
  Re: optimum power supply for subway/light rail lines Morten Reistad <first@last.name.invalid> - 2015-08-24 21:42 +0200
    Re: optimum power supply for subway/light rail lines Stephen Sprunk <stephen@sprunk.org> - 2015-08-24 15:14 -0500
      Re: optimum power supply for subway/light rail lines hancock4@bbs.cpcn.com - 2015-08-25 08:07 -0700
        Re: optimum power supply for subway/light rail lines Stephen Sprunk <stephen@sprunk.org> - 2015-08-25 12:52 -0500
          Re: optimum power supply for subway/light rail lines scott@slp53.sl.home (Scott Lurndal) - 2015-08-25 20:06 +0000
  Re: optimum power supply for subway/light rail lines Jon Elson <elson@pico-systems.com> - 2015-08-24 23:33 -0500
    Re: optimum power supply for subway/light rail lines Stephen Sprunk <stephen@sprunk.org> - 2015-08-25 01:39 -0500
      Re: optimum power supply for subway/light rail lines Morten Reistad <first@last.name.invalid> - 2015-08-25 10:23 +0200
        Re: optimum power supply for subway/light rail lines Stephen Sprunk <stephen@sprunk.org> - 2015-08-25 12:30 -0500
          Re: optimum power supply for subway/light rail lines Morten Reistad <first@last.name.invalid> - 2015-08-25 22:48 +0200
            Re: optimum power supply for subway/light rail lines Stephen Sprunk <stephen@sprunk.org> - 2015-08-26 10:44 -0500
              Re: optimum power supply for subway/light rail lines Morten Reistad <first@last.name.invalid> - 2015-08-26 18:03 +0200
              Re: optimum power supply for subway/light rail lines hancock4@bbs.cpcn.com - 2015-08-26 12:04 -0700
      Re: optimum power supply for subway/light rail lines Jon Elson <jmelson@wustl.edu> - 2015-08-25 14:15 -0500
        Re: optimum power supply for subway/light rail lines Stephen Sprunk <stephen@sprunk.org> - 2015-08-25 15:15 -0500
          Re: optimum power supply for subway/light rail lines hancock4@bbs.cpcn.com - 2015-08-25 13:33 -0700
            Re: optimum power supply for subway/light rail lines Stephen Sprunk <stephen@sprunk.org> - 2015-08-25 15:49 -0500
              Re: optimum power supply for subway/light rail lines danny burstein <dannyb@panix.com> - 2015-08-25 21:00 +0000
                Re: optimum power supply for subway/light rail lines Stephen Sprunk <stephen@sprunk.org> - 2015-08-25 16:37 -0500
                Re: optimum power supply for subway/light rail lines lawrence@cluon.com - 2015-08-25 23:52 +0200
                fluorescents, was: optimum power supply for subway/light rail lines danny burstein <dannyb@panix.com> - 2015-08-25 22:25 +0000
                Re: fluorescents, was: optimum power supply for subway/light rail lines lawrence@cluon.com - 2015-08-26 04:13 +0200
                Re: fluorescents, was: optimum power supply for subway/light rail lines hancock4@bbs.cpcn.com - 2015-08-25 20:24 -0700
                Re: optimum power supply for subway/light rail lines JimP <solosam90@gmail.com> - 2015-08-25 19:11 -0500
                Re: optimum power supply for subway/light rail lines hancock4@bbs.cpcn.com - 2015-08-25 20:36 -0700
                Re: optimum power supply for subway/light rail lines Michael Black <et472@ncf.ca> - 2015-08-26 02:29 -0400
                Re: optimum power supply for subway/light rail lines JimP <solosam90@gmail.com> - 2015-08-26 09:35 -0500
              Re: optimum power supply for subway/light rail lines andrew@cucumber.demon.co.uk (Andrew Gabriel) - 2015-10-11 17:24 +0000
                Re: optimum power supply for subway/light rail lines hancock4@bbs.cpcn.com - 2015-10-13 07:30 -0700
                Re: optimum power supply for subway/light rail lines andrew@cucumber.demon.co.uk (Andrew Gabriel) - 2015-10-15 19:32 +0000
            Re: optimum power supply for subway/light rail lines danny burstein <dannyb@panix.com> - 2015-08-25 20:52 +0000
              Re: optimum power supply for subway/light rail lines "Joseph D. Korman" <joekor@earthlink.net> - 2015-08-28 14:34 -0400
            Re: optimum power supply for subway/light rail lines Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2015-08-26 04:03 +0000
          Re: optimum power supply for subway/light rail lines danny burstein <dannyb@panix.com> - 2015-08-25 20:36 +0000
    Re: optimum power supply for subway/light rail lines hancock4@bbs.cpcn.com - 2015-08-25 08:10 -0700
      Re: optimum power supply for subway/light rail lines Stephen Sprunk <stephen@sprunk.org> - 2015-08-25 12:18 -0500
        Re: optimum power supply for subway/light rail lines danny burstein <dannyb@panix.com> - 2015-08-25 17:30 +0000
  Re: optimum power supply for subway/light rail lines Quadibloc <jsavard@ecn.ab.ca> - 2015-10-12 22:15 -0700
    Re: optimum power supply for subway/light rail lines hancock4@bbs.cpcn.com - 2015-10-13 07:37 -0700
    Re: optimum power supply for subway/light rail lines Stephen Sprunk <stephen@sprunk.org> - 2015-10-14 13:15 -0500
      Re: optimum power supply for subway/light rail lines hancock4@bbs.cpcn.com - 2015-10-14 12:37 -0700
        Re: optimum power supply for subway/light rail lines Stephen Sprunk <stephen@sprunk.org> - 2015-10-14 14:57 -0500
          Re: optimum power supply for subway/light rail lines hancock4@bbs.cpcn.com - 2015-10-14 13:30 -0700
            Re: optimum power supply for subway/light rail lines Stephen Sprunk <stephen@sprunk.org> - 2015-10-15 11:26 -0500
              Re: optimum power supply for subway/light rail lines hancock4@bbs.cpcn.com - 2015-10-16 07:19 -0700
                Re: optimum power supply for subway/light rail lines Stephen Sprunk <stephen@sprunk.org> - 2015-10-16 15:55 -0500
                Re: optimum power supply for subway/light rail lines Morten Reistad <first@last.name.invalid> - 2015-10-17 00:10 +0200
                Re: optimum power supply for subway/light rail lines Stephen Sprunk <stephen@sprunk.org> - 2015-10-21 13:12 -0500
                Re: optimum power supply for subway/light rail lines hancock4@bbs.cpcn.com - 2015-10-21 13:23 -0700
                Re: optimum power supply for subway/light rail lines Peter Flass <peter_flass@yahoo.com> - 2015-10-21 17:56 -0400
                Re: optimum power supply for subway/light rail lines scott@slp53.sl.home (Scott Lurndal) - 2015-10-22 17:53 +0000
                Re: optimum power supply for subway/light rail lines John Levine <johnl@iecc.com> - 2015-10-24 00:46 +0000
                Re: optimum power supply for subway/light rail lines Walter Bushell <proto@panix.com> - 2015-11-04 12:38 -0500
                Re: optimum power supply for subway/light rail lines Peter Flass <peter_flass@yahoo.com> - 2015-10-21 17:56 -0400
                Re: optimum power supply for subway/light rail lines Stephen Sprunk <stephen@sprunk.org> - 2015-10-22 10:56 -0500
                Re: optimum power supply for subway/light rail lines hancock4@bbs.cpcn.com - 2015-10-22 10:09 -0700
                Re: optimum power supply for subway/light rail lines Morten Reistad <first@last.name.invalid> - 2015-10-22 19:44 +0200
                Re: optimum power supply for subway/light rail lines Stephen Sprunk <stephen@sprunk.org> - 2015-10-22 14:38 -0500
                Re: optimum power supply for subway/light rail lines Morten Reistad <first@last.name.invalid> - 2015-10-22 23:40 +0200
                Re: optimum power supply for subway/light rail lines Stephen Sprunk <stephen@sprunk.org> - 2015-10-23 13:29 -0500
                Re: optimum power supply for subway/light rail lines hancock4@bbs.cpcn.com - 2015-10-23 11:39 -0700
                Re: optimum power supply for subway/light rail lines Michael Black <et472@ncf.ca> - 2015-10-23 15:52 -0400
                Re: optimum power supply for subway/light rail lines Ahem A Rivet's Shot <steveo@eircom.net> - 2015-10-23 21:40 +0100
                Re: optimum power supply for subway/light rail lines Stephen Sprunk <stephen@sprunk.org> - 2015-10-23 16:55 -0500
                Re: optimum power supply for subway/light rail lines Morten Reistad <first@last.name.invalid> - 2015-10-23 22:18 +0200
                Re: optimum power supply for subway/light rail lines Stephen Sprunk <stephen@sprunk.org> - 2015-10-25 21:04 -0500
                Re: optimum power supply for subway/light rail lines Peter Flass <peter_flass@yahoo.com> - 2015-10-26 07:17 -0400
                Re: optimum power supply for subway/light rail lines "Charles Richmond" <numerist@aquaporin4.com> - 2015-10-26 14:48 -0500
                Re: optimum power supply for subway/light rail lines Stephen Sprunk <stephen@sprunk.org> - 2015-10-26 15:54 -0500
                Re: optimum power supply for subway/light rail lines "78lp" <78lp@nospam.com> - 2015-10-28 07:07 +1100
                Re: optimum power supply for subway/light rail lines Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2015-10-23 21:36 +0000
                Re: optimum power supply for subway/light rail lines "78lp" <78lp@nospam.com> - 2015-10-24 16:01 +1100
                Re: optimum power supply for subway/light rail lines "78lp" <78lp@nospam.com> - 2015-10-23 08:19 +1100
                Re: optimum power supply for subway/light rail lines Peter Flass <peter_flass@yahoo.com> - 2015-10-23 05:57 -0400
                Re: optimum power supply for subway/light rail lines Dave Garland <dave.garland@wizinfo.com> - 2015-10-22 14:12 -0500
                Re: optimum power supply for subway/light rail lines Stephen Sprunk <stephen@sprunk.org> - 2015-10-23 14:27 -0500
                Re: optimum power supply for subway/light rail lines Dave Garland <dave.garland@wizinfo.com> - 2015-10-23 16:16 -0500
                Re: optimum power supply for subway/light rail lines hancock4@bbs.cpcn.com - 2015-10-23 20:05 -0700
                Re: optimum power supply for subway/light rail lines Stephen Sprunk <stephen@sprunk.org> - 2015-10-25 00:53 -0500
                Re: optimum power supply for subway/light rail lines "78lp" <78lp@nospam.com> - 2015-10-25 17:49 +1100
                car rentals, was: optimum power supply for subway/light rail lines danny burstein <dannyb@panix.com> - 2015-10-25 12:47 +0000
                Re: optimum power supply for subway/light rail lines hancock4@bbs.cpcn.com - 2015-10-23 19:55 -0700
                Re: optimum power supply for subway/light rail lines Peter Flass <peter_flass@yahoo.com> - 2015-10-24 07:16 -0400
                Re: optimum power supply for subway/light rail lines Greymaus <mausg@mail.com> - 2015-10-24 18:11 +0000
                Re: optimum power supply for subway/light rail lines hancock4@bbs.cpcn.com - 2015-10-24 20:18 -0700
                Re: optimum power supply for subway/light rail lines Stephen Sprunk <stephen@sprunk.org> - 2015-10-24 23:55 -0500
                Re: optimum power supply for subway/light rail lines scott@slp53.sl.home (Scott Lurndal) - 2015-10-22 18:01 +0000

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