Path: ...!news-out.netnews.com!postmaster.netnews.com!us3.netnews.com!not-for-mail X-Trace: DXC=2I9TDMRKeYZaYSTYGbe1bRHWonT5<]0T]Q;nb^V>PUfV5[gZBW6J?L\RQ?47NQ;EP[bSPL1gF:iGRXem9Faci`V^nT9[Xo\4=n^`HlOj^:MhMP;E40TK^[G`^ X-Complaints-To: support@blocknews.net From: Mike Mocha Subject: Re: Philips TL-S bulbs Newsgroups: sci.electronics.design X-Face: $U`Uhy}9baNge-Vz>P*B?Kz''{nI8:v8([FP0v!x|*5U!g!A5Mh l3J\[-\6x(l<Y5~\q23Ic>%!R)QksWH#{/2_/j'7N\"J`*Z$5AVkVkv _K5tk|@k_)(6Fz\ZsxhTEkSLeo1nsu7\Z<V(3rSrwl"J;aIwiq%k=Q<&apos ;,|&V+lJc({~zA8fx=63iKrI#bNO+$'1;0b=90/a6zwIO)B0_(KJg#}^b$Z}rx T=3= References: <6615961d$0$897423$882e4bbb@reader.netnews.com> <1qrsilx.5w68h73o0kh2N%liz@poppyrecords.invalid.invalid> <6616ad68$0$2422113$882e4bbb@reader.netnews.com> <1qrt6f6.k0gyz21esr0dsN%liz@poppyrecords.invalid.invalid> MIME-Version: 1.0 Organization: --==RHW==-- x-no-archive: yes User-Agent: Pan/0.155 (Kherson; fc5a80b8) Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Date: 11 Apr 2024 05:56:26 GMT Lines: 40 Message-ID: <66177b8a$0$1643526$882e4bbb@reader.netnews.com> NNTP-Posting-Host: 127.0.0.1 X-Trace: 1712814986 reader.netnews.com 1643526 127.0.0.1:33291 Bytes: 3112 On Wed, 10 Apr 2024 17:16:42 +0100, Liz Tuddenham wrote: > Mike Mocha wrote: > >> On Wed, 10 Apr 2024 08:44:52 +0100, Liz Tuddenham wrote: >> >> > Mike Mocha wrote: >> > >> >> Hey all, >> >> >> >> I have an old rail car design that used ballast-free florescent >> >> tubes in a 600 VDC circuit; bulbs used in series with power >> >> resistors, the circuit basically put 100 VDC or 60 VDC over each >> >> bulb. There's no AC source on the car. >> > >> > I think those tubes needed special switches to reverse the polarity >> > each time they were switched on. This was to prevent darkening of >> > one end of the tube after a few hours, caused by migration of the >> > mercury. You may have to replace the switchgear if you fit >> > inverter-powered lamps. >> > >> > If you contact a tramcar manufacturer, they should be able to put you >> > in touch with some companies that supply modern lighting equipment >> > for 600 VDC. >> >> You might be correct about this in terms of a good practice, but in the >> design I'm dealing with this is not the case, and thus possibly the >> reason so many of the tubes burned out. > > Are you sure they have, in fact, burnt out? If they have gone black at > one end, that is most likely because of the mercury migration problem. > Reversing the polarity should restore them for a short while until the > mercury migrates the other way. > > There is a lot of information about this in the Philips Technical > Review, I remember reading it but can't remember the date (it might have > been in the 1930s). That's actually a good point. I don't think the maintenance people tried that. I'll go and check if they still have the bad bulbs. Thanks.