Author Topic: Strobing Mercury Vapor Lamp  (Read 2819 times)
form109
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Strobing Mercury Vapor Lamp « on: July 01, 2009, 04:36:58 PM » Author: form109
video of my GE 175 Watt Hungarian Merc strobing upon restriking.

http://www.youtube.com/watch?v=dUDpdrXACGM&feature=related
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Medved
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Re: Strobing Mercury Vapor Lamp « Reply #1 on: July 01, 2009, 05:18:00 PM » Author: Medved
This is normal, when capacitor is in series with the lamp and the OCV is only marginal to start the lamp (e.g. upon hot restrike). The probe-start system is able to start an arc only, when the probe is positive (so the main electrode where the probe is located is negative) - let's call this "positive halfperiod".
When the arc first strike (the positive half-period), it charges the capacitor in the way the voltage at the lamp lower in this half-period. So next (negative) half-period (where the probe is not effective) the voltage is higher, but might be still not sufficient to restrike the arc - it depend on it's temperature. When it does restrike, the capacitor charges back, so allowing to restrike in the next positive half-period as well - so the arc start to "steady burn". But when the voltage on the "negative" half-period is not sufficient, the capacitor keep it's charge and this lower the voltage in the next positive half-period, so it doesn't strike even with the probe being effective otherwise. As the discharge from the probe during negative half-period is there (even if not effective to set the main current path), it draw some current from the capacitor (via the probe's resistor), lowering it's voltage, till it is sufficiently low for the positive half-period to reignite.
This cycle repeat, so lamp flashes, until it cool down enough to be able to restrike the arc in the "negative" half-period as well, so settle the "stable" arc.
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form109
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Re: Strobing Mercury Vapor Lamp « Reply #2 on: July 01, 2009, 05:50:10 PM » Author: form109
No Capaciator Here. :)
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Medved
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Re: Strobing Mercury Vapor Lamp « Reply #3 on: July 01, 2009, 06:08:25 PM » Author: Medved
Then this flashing might have its root-cause in gas temperature: It cool down, till it ignite for short time. But before electrodes heat up, the gas heat-up first, so again too hot for restrike, so you might have such flashes.
On ballasts with capacitors (CWA, CWI) this happen very often (due to rectifying mechanism described before), on others it is more rare phenomenon, but in most cases if this happen or not depend on exact lamp condition, i would even say "mood"...
In any case i would consider it normal, unless it happen on cold lamp (but not in exceptionally cold weather).

P.S. What ballast you are using?
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form109
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Re: Strobing Mercury Vapor Lamp « Reply #4 on: July 01, 2009, 06:30:34 PM » Author: form109
Then this flashing might have its root-cause in gas temperature: It cool down, till it ignite for short time. But before electrodes heat up, the gas heat-up first, so again too hot for restrike, so you might have such flashes.
On ballasts with capacitors (CWA, CWI) this happen very often (due to rectifying mechanism described before), on others it is more rare phenomenon, but in most cases if this happen or not depend on exact lamp condition, i would even say "mood"...
In any case i would consider it normal, unless it happen on cold lamp (but not in exceptionally cold weather).

P.S. What ballast you are using?


whats powering the Lamp is Three Transformers Wired to provide the Proper Opperating Current....see What i used here
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Re: Strobing Mercury Vapor Lamp « Reply #5 on: July 02, 2009, 12:56:37 AM » Author: Medved
And how it was wired, as serial reactor, or HX "transformer"? If the OCV was low, it might "invite" the flashing phenomenon...
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form109
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Re: Strobing Mercury Vapor Lamp « Reply #6 on: July 02, 2009, 01:12:58 AM » Author: form109
And how it was wired, as serial reactor, or HX "transformer"? If the OCV was low, it might "invite" the flashing phenomenon...

Not sure if it was a Serial Reactor or HX.....the Large Blue transformer steps 120 up to 240....the 240 Side is then connected to a 70 Watt HPS Ballast and a Microwave oven Primary....this is then connected in Series with the lamp.
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