Battle of the Bulge

Was looking through some of the collection of halides in the collection and I decided to compare these two tubular metal halide lamps which feature bulged outer jackets: a Sylvania MetalArc HSI-THX and an Osram PowerStar HQI-BT 400W/D.
This was done as the outers sometimes overheated and was sucked in by the vacuum.

You can't really compare them as they are designed for different control gear but it is interesting to see the differences in contruction.
At least I thought so anyway lol.

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Comment 1 to 6 of 6

Page: 1

Andy

[11 Jan, 2022 at 09:17 PM]

I have one of the Sylvania Metalarc HSI-THX 400W/4K lamps just like the one you have here. The lamp is nothing out of the ordinary but has sadly recently become very special to me as it was bought for me my a friend I have known for 30 years that passed away suddenly just before Christmas. You mention that these two lamps are designed for different control gear. Can you tell me what this specific gear is please? The reason I ask is that the 400W Lowbay light in my parents' garage happily runs another of these HSI-THX lamps and the gear in that is a 4.4A HPS/SON Ballast.

FrontSideBus

[12 Jan, 2022 at 08:48 AM]

AFIAK the Osram is for SON gear and the Sylvania is for MBF.

Lightbulbfun

[12 Jan, 2022 at 05:55 PM]

if you search for HSI-THX sylvania still has the page up for them, looks like they are rated for both MBF and SON ballasts, but I think going by the wording they are optimised for MBF chokes? but dont quote me on that!, its interesting comparison here, it bugs me that the Sylvania lamps arc tube is not mounted centrally in the bulge LOL

Andy

[13 Jan, 2022 at 09:11 PM]

The only info I was able to find was the lamp "can also be operated on SHP control gear resulting in both different output and colour temperature". No details were provided for what the difference in output or colour temperature would be.

FrontSideBus

[14 Jan, 2022 at 01:47 PM]

The datasheet I have says the same "HX family of metal halide lamps for use with Mercury ballast with soft ignitor, - HX family can also be operated on SHP control gear resulting in both different output and colour temperature." However it lists in the electrical characteristics that it runs at 3.4a at 130v. Which to me says mercury with a 750v parallel ignitor as SON is like 4.4-4.6a. As a personal rule if I'm not sure, if it has an aux electrode I first assume MBF + SI51.
They probably put the note about SON gear in because they know that people will run them on SON gear and they will work but will not quite to the spec listed.

Andy

[14 Jan, 2022 at 06:09 PM]

That's a good rule of thumb Mark. An aux electrode lamp should start with a softer ignitor like the SI51. Smile

Comment 1 to 6 of 6

Page: 1