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From: Mike Mocha <mocha@mailexcite.com>
Subject: Re: Philips TL-S bulbs
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Date: 10 Apr 2024 15:16:56 GMT
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On Wed, 10 Apr 2024 08:44:52 +0100, Liz Tuddenham wrote:

> Mike Mocha <mocha@mailexcite.com> 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.  I am in contact with several companies 
that supply low voltage LED lighting for rail vehicles as a parallel path.