Philips TL-S bulbs

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 can't find these tubes on the market anymore.  The last time we
purchased them was in 2007 and they had to be manufactured special by
Philips.  We're thinking of moving to regular T8 tubes with a DC inverter
ballast.  Anyone here know more about why these are not made anymore or
have any ideas where to look?

Thanks,
Mike


https://www.assets.lighting.philips.com/is/content/PhilipsLighting/
comf2571-pss-global