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SBMV burning without main filament?

SBMV burning without main filament?

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So, I tried to take a video of dimming my SBMV but the auto-iris doesn't help nor does the extremely low resolution, however I came across an interesting effect, and here are the stills. After burning the lamp at 50% for an extended time, the thermal switch started to chatter open & closed as the lamp temperature decreased (much like photocontrols may do right at their on/off point). First, the starting filaments began to heat, which put out the arc, so then the series filament went out too, but then there was a re-ignition attempt, with just a mercury arc for about two seconds....with no visible illumination of the main filament! It appears to be ballasted by the starting filaments in the arc tube. After a few seconds of cool down and resetting the dimmmer to 100%, the lamp re-lit normally.

Sylvania_200w_incandescent+.JPG Luma_LU35+~0.jpg SBMV_extinction.jpg SBMV_dimming.JPG

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Filename:SBMV_extinction.jpg
Album name:arcblue / Bulbs in captivity
Keywords:Lamps
File Size:36 KB
Date added:Sep 08, 2014
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ace100w120v
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Sep 08, 2014 at 09:54 PM Author: ace100w120v
Wonder if it would eventually relight while still dimmed?
I did something similar but with a 175w clear Philips H39 on a standard HX-NPF ballast in a yardblaster, again with a standard Lutron TRIAC incandescent wall dimmer. It sorta worked...similar in that it would dim but only slowly. If started up dim it would never warm up, or at least take a very long time. I also had an incandescent lamp (I think 75w) on the dimmer to keep a resistive load going on it instead of purely inductive.
dor123
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Sep 09, 2014 at 02:37 AM Author: dor123
In the pictures that the main filament don't lighting at all, the ballasting filament still ballasting the arctube, but it is too cold for its black body radiation to be visible.
The preheating filaments can't ballast the arctube.

I"m don't speak English well, and rely on online translating to write in this site.
Please forgive me if my choice of my words looks like offensive, while that isn't my intention.

I only working with the European date format (dd.mm.yyyy).

I lives in Israel, which is a 230-240V, 50hz country.

rjluna2
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Sep 09, 2014 at 05:14 AM Author: rjluna2
The resistance on the preheat filaments are higher than the main filament. That is why you don't see much of blackbody radiation on the main filament. See my Philips 4 Watts vs. 15 Watts C7 bulbs experiment.

Pretty, please no more Chinese failure.

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Nov 04, 2018 at 11:31 AM Author: trojmiejski
Last month I was doing experiments with Philips ML 100W 225V-235V coated SBMV on a dimmer on 230V 50Hz mains. On lowest dimmer setting a cold lamp strikes in such a way that filament does not glow and the arc is dim enough that the whole bulb is pink, due to fluorescence of phosphor coating, exactly like in a normal MV just after start. When the dimmer is turned up to 100%, the lamp is allowed to run up to full brightness and then the dimmer is turned back to lowest setting, lamp goes off but when it restrikes after a while, the arc is stronger than in a case of a cold lamp and much more bluish-green, with the filament still not glowing. However the arc isn't exactly stable and continuosly jumps between normal electrode and neighboring starting electrode (SBMV for 230V mains have a starting electrode like normal MV lamps).
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