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Groups > alt.folklore.computers > #150415
| From | danny burstein <dannyb@panix.com> |
|---|---|
| Newsgroups | alt.folklore.computers, nyc.transit |
| Subject | Re: optimum power supply for subway/light rail lines |
| Date | 2015-08-25 20:52 +0000 |
| Organization | PANIX Public Access Internet and UNIX, NYC |
| Message-ID | <mrikig$bd3$1@reader1.panix.com> (permalink) |
| References | <5932e6a1-4930-466c-8bb8-4baadf9e9e77@googlegroups.com> <mriia7$435$1@dont-email.me> <aae3cc73-00f8-4ddf-944b-b154a3b2ee7f@googlegroups.com> |
Cross-posted to 2 groups.
In <aae3cc73-00f8-4ddf-944b-b154a3b2ee7f@googlegroups.com> hancock4@bbs.cpcn.com writes: >Somewhere I heard (unconfirmed) that subway train lamps had a relay to peri >odically switch polarity of the DC supply to the lamps back and forth. FWI >W, in the transit museum, some of the cars on exhibit remain still for long > periods of time, and one of their interior fl. lights is dark. Could that > have something to do with the polarity not being switched? Eyup. Back in roughly 1980 I had this really great booklet from Westinghouse which described their lighting products. (Alas it's gone to that great dustbin of history). They had a section about powering fluorescents via DC and mentioned the one-side darkening... and the importance of periodically flipping the current flow direction. The simple solution they recommended? Having a switch that reversed the polarity each time it was turned on. That stuck in my brane... and sometime later I was on one of the retrofitted subway cars which had been upgraded to fluorescent. And eyup, one of the tubes on the destination signs was dark on one side. We went over a switch which, at the time of the subway system design and that type of car.. gave us a couple of seconds of power outage (the battery powered emergency lights came on). When power was restored, the tube was fine... Speaking of which, anyone know if the trains still use lead acid storage batteries? >When they rebuilt the RDG Blueliners, they put in fluorescent lights. Whil= >e standing in Reading Terminal, the flicker was very evident, although it w= >asn't once the trains got moving. >Old subway trains would briefly lose the lights when the train passed a 3rd= > rail gap, which were frequent (usually near every station). Modern train= >s have battery supply so the lights stay on (though you can hear the HVAC w= >hoose cease). However, if the train is moving slowly over a crossover with= > a longer 3rd rail gap, the lights will go out. -- _____________________________________________________ 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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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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