Groups > alt.folklore.computers > #150416

Re: optimum power supply for subway/light rail lines

From	danny burstein <dannyb@panix.com>
Newsgroups	alt.folklore.computers
Subject	Re: optimum power supply for subway/light rail lines
Date	2015-08-25 21:00 +0000
Organization	PANIX Public Access Internet and UNIX, NYC
Message-ID	<mril0o$23o$1@reader1.panix.com> (permalink)
References	(2 earlier) <mrh2g0$1an$1@dont-email.me> <NqOdnaOjzuhXI0HInZ2dnUU7-KGdnZ2d@giganews.com> <mriia7$435$1@dont-email.me> <aae3cc73-00f8-4ddf-944b-b154a3b2ee7f@googlegroups.com> <mrika0$c0e$1@dont-email.me>

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In <mrika0$c0e$1@dont-email.me> Stephen Sprunk <stephen@sprunk.org> writes:

>> In the 1950s, they began to use fluorescent lights in the subway.
>> Don't they require a/c?  Did they use an inverter?

>They were probably running on 25Hz AC.  I'm not sure if they can run on
>DC even today, much less back then; if so, it's quite uncommon.

What, you haven't seen portable camping lamps with fluorescent
tubes? Much more battery life than incandescents.

Pretty much lost to history now.. Also, they weren't very common
as they were more delicate.

>Fluorescents _do_ generally require higher voltages.  120VAC tubes for
>homes are relatively new; office ones are typically 277VAC, which can
>run directly off one leg of a standard 480VAC three-phase supply.

Voltage requirements are directly related to tube length.
The 600VDC in the NYC subway was more than enough to handle
the two foot lamps in the destiantion signs on the sides
of the train. Not sure if the overheads were two or four.

>I'm familiar with how fluorescent bulbs work, and I can't think of any
>reason why polarity switching would matter, but it's possible; I've
>never tried to run them on DC myself or seen anyone else do so.  If it
>was necessary, could a relay really do it fast enough?

Again, it's not for the light production. It's for dealing
with the sputtering and electrode issues. So having it switch
over every half hour or even once/day would be fine.

-- 
_____________________________________________________
Knowledge may be power, but communications is the key
		     dannyb@panix.com 
[to foil spammers, my address has been double rot-13 encoded]

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Thread

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 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

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