Author Topic: Why can't HID lamps preheat-start  (Read 3550 times)
imj
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Why can't HID lamps preheat-start « on: October 03, 2013, 07:30:53 AM » Author: imj
I just saw a Youtube video about HQI lamp having preheat start. Just type in warmstart HQI on Youtube. So it can be done but it's not selling as mainstream technology.
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dor123
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Re: Why can't HID lamps preheat-start « Reply #1 on: October 03, 2013, 08:13:07 AM » Author: dor123
Post the video.
The only preheat HID lamps I've heard and seen, are the american and japanese 120V SBMV lamps, that uses small filaments and a thermal switch to preheat the main electrodes.
Preheating electrodes of HID lamps is a very expensive and complicated solution which requires a special base, if it is done with an external starter. Also, HID lamps are usually designed to be started one time per day.
The ignition is one of the least damaging action for the electrodes of HID lamps, as their shape are immune to cold starting.
The only electrode damaging process in HID lamps, is the run-up.
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imj
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Re: Why can't HID lamps preheat-start « Reply #2 on: October 03, 2013, 08:31:12 AM » Author: imj
http://www.youtube.com/watch?v=K1ngaIUzYY0 Looks like it's the usual two wire lamp connection.
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dor123
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Re: Why can't HID lamps preheat-start « Reply #3 on: October 03, 2013, 10:33:07 AM » Author: dor123
OMG!!! A metal halide lamp that starts like a fluorescent on an Eltam Perfekt-Start or a pulsestarter!!!
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Re: Why can't HID lamps preheat-start « Reply #4 on: October 03, 2013, 10:39:04 AM » Author: Ash
Niiiiice!!

It looks like the electrodes heat up before there is arc, so does it have fiament electrodes ?
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dor123
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Re: Why can't HID lamps preheat-start « Reply #5 on: October 03, 2013, 10:48:40 AM » Author: dor123
I setted this video at full screen and maximum resolution, and seen that the electrodes are the same electrodes of standard MH lamp, but preheated with external preheating filaments like american and japanese 120V SBMV lamps. The preheating is done by a glow starter and not by a thermal starter like the 120V SBMV lamps.
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Re: Why can't HID lamps preheat-start « Reply #6 on: October 03, 2013, 11:18:01 AM » Author: imj
Glow Starter? There's no glow starter as far as I can see. Could be thermal switch (glass tube at base area) which explains the filaments remaining on even after the arc struck.
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Re: Why can't HID lamps preheat-start « Reply #7 on: October 03, 2013, 01:08:46 PM » Author: dor123
The filaments turns off after the arc is struck. But the main electrodes glowing the same color as the filaments, which gives an illution that the filaments continues to light, while this isn't the case.
The thermal starter needs a heating element in order to operate, so I don't know how they managed to enclose it inside a bottle. It also have a fast respone time, like Eltam Perfekt-Start R1 and A, and unlike the snap starter of the GEC Solarcolour SON-I.
Also, I don't hear a clicking sound. Probably this thermal starter isn't a snap starter.
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Re: Why can't HID lamps preheat-start « Reply #8 on: October 03, 2013, 01:20:41 PM » Author: dor123
I think that it is also possible that the starter is solenoid based, as there is no room for a heater.
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Re: Why can't HID lamps preheat-start « Reply #9 on: October 03, 2013, 02:23:44 PM » Author: imj
The 'glow bottle' at the base area appears to have what looks like a heater coil inside. Maybe when power is switched on all the current goes through the filaments and the heater coil in the 'glow bottle' so when the heater quickly heats up the bi-metal contacts open and shuts off the filaments. The contacts cool very slowly as in SON(I)lamps and would have no chance to close since the arctube would have radiated enough heat to keep them open indefinitely until power is cut off from the lamp the contacts close back. I think this kind of starting is depending that arctube will strike on time if it misses the window it will not light or wait till the contacts close and reheat the filaments.
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Re: Why can't HID lamps preheat-start « Reply #10 on: October 03, 2013, 03:23:17 PM » Author: Medved
It look more like a thermal starter: Current passing through heat up the bi-metal contact, what then snap open. Then the heat from the arc (it's IR) heat that further, so preventing reclosing.

And why it is not used? There would be two aspects:
First the need for that: It mean a more expensive lamp. And as it will need few minutes heat up to full brightness and inability of an instant restrike mean it won't be usable for short ON time anyway, so simpler and cheaper cold started concept won.
And the fact the lamp uses filaments does not have to mean it really hot start: The arc may start on the filaments and only then flash over to the main electrodes.
And finally the HID electrodes are way more robust than the fluorescent: They have way larger reserve of the active emitter material compare to fluorescents (for MH the complete electrode body, compare to only a filament coat on the fluorescents)

Second the efficacy:
The main problems with MH lamp efficacy was always the ability to have as high as possible cold spot temperature, so the fill mix could be made to reach higher efficacy and color quality. As the seal area tend to be the coldest spot, the intention is to make it as small as possible. And this was the main reason, why the probe start lamps never achieved such efficacy as pulse start: The pulse start suffice with only one feed on each tube end, while the probe start need two of them at least on one end.
And the "preheat" then require two sealed feeds on each end, so posing even more troubles with the cold spot than the probe start MH's.
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Re: Why can't HID lamps preheat-start « Reply #11 on: October 04, 2013, 12:44:44 AM » Author: imj
Still a cool start-up.
« Last Edit: October 04, 2013, 01:17:45 AM by imj » Logged
dor123
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Re: Why can't HID lamps preheat-start « Reply #12 on: October 04, 2013, 02:13:45 AM » Author: dor123
I think that preheating the electrodes of HID lamp, can still prolong their life.
If you have seen the nature of ignition of MV, HPS and MH lamps, you noted that it is full of flashes and rectifications when the arc is struck.
This preheat MH lamp don't rectify or flickers at all during ignition when the arc is struck after the electrodes preheated. This is the same with 120V SBMV lamps (Their arctubes don't rectify or flickers at all when the arc is struck.
This is also the same with fluorescent lamps: In a preheat/switchstart ballast and a glow starter, if the starter cold started the lamp or the lamp managed to start directly from the mains/ballast OCV, it will often rectify. If the lamp started when the electrodes were sufficiently hot, no rectification occurs at all.
So I think that the eliminating of the flickering and flashing of cold starting of HID lamps by preheating their electrodes, should prolong their life.
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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 international date format (dd.mm.yyyy).

I lives in Israel, which is a 220-240V, 50hz country.

imj
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Re: Why can't HID lamps preheat-start « Reply #13 on: October 04, 2013, 07:41:06 AM » Author: imj
I guess it suffered the same fate as the white arctube mercury lamp where the arctube dosen't blacken but turns whitish around the electrode area still allows light. It also made the lamp last too long so the manufacturers discontinued it. In this case it is expensive to manufacture and last way too long so I think  the manufacturer cannot earn back the profit within a short time. But I'm sure it would be made in an altruistic world as mainstream.
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Medved
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Re: Why can't HID lamps preheat-start « Reply #14 on: October 04, 2013, 12:58:47 PM » Author: Medved
With 10hours per start or more the starting method does not make as much difference anymore
So it could prolong the lamp life a bit, but the efficacy will suffer, as lamps of these power levels consume way more money via the electricity than the replacement bulb cost itself, so the higher efficacy (so lower wattage / less fixtures) pay off itself many times, even if that mean more frequent relamping (mainly with well scheduled group relamping).

The 120V SBMV use the complex preheat assembly, as there is no other method technically feasible. But with regular HID ballasts the pulse ignition is already thge cheapest to run method (and it would be so even for MV, if MV won't be considered obsolete for so many decades and some real development would take place there)
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