Questions On The Code > General Discussions on Code
List of Current ratings for fluorescent lamps
Adderall:
--- Quote ---I will be really interested to hear! Thanks!!!
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From the 1972 version. pre-heat specs for
F15T8 15W nominal, 18" nom length
0.3A 55v 14.5W approx. Pre-heat cathodes current range 0.65-0.44A
F30T8 30W nominal 36"nom length.. I have no idea if the length is exactly the same as the new type F25T8. Nominal length means as much as 2x4 lumber is 2" x 4", when it really isn't...
0.36A 98V 30.0w approx. Pre-heat cathodes range 0.65-0.40A
The voltage is set by the lamp. When you apply the specified current above at line frequency, that's the operating lamp voltage you can expect. V * I don't add up to watts, because at 50/60 Hz, lamp power factor < 1.0. It appears to be around 0.85.
I predict that F15T8 will operate fine on PRS ballasts designed for F17/25/32 T8s in series. If you use an IS, you may have a premature lamp failure. If you use it on a high ballast factor ballast meant for F32, but not shorter lamps, you may have a ballast failure.
F30T8 will be under-driven, but should run fine. Again, ISing pre-heat lamp will probably cause pre-mature failure.
I have a bunch of F17/25/32 programmed start ballasts, but don't have any F30T8 lamps or3' fixtures, so I can't test it.
Regular magnetic rapid start ballasts depend on having precise OCV to ensure arc strikes just at the right time, so using any unsupported lamp will result in ignition problems or premature lamp failure. programmed start heats the filaments before applying arc voltage, so OCV doesn't really matter much, as long as it's high enough. You can't sputter the filament once they've been pre-heated.
Medved:
@Adderall: For programmed start ballasts you should be careful, as most of their designs (now i mean HF electronic) actually put voltage across the lamp, but they expect this voltage to be low enough, so it does not initiate the discharge in the lamp. But this expectation is valid only for rated lamp types, so lamp with lower striking voltage might ignite prematurely, so it's life would be compromised.
But generally the lamp striking voltage range is way wider then for RS ballast, what yield to way more reliable starting and longer cycle life for rated lamp.
Adderall:
--- Quote from: Medved on June 01, 2010, 04:39:48 PM ---@Adderall: For programmed start ballasts you should be careful, as most of their designs (now i mean HF electronic) actually put voltage across the lamp, but they expect this voltage to be low enough, so it does not initiate the discharge in the lamp. But this expectation is valid only for rated lamp types, so lamp with lower striking voltage might ignite prematurely, so it's life would be compromised.
But generally the lamp striking voltage range is way wider then for RS ballast, what yield to way more reliable starting and longer cycle life for rated lamp.
--- End quote ---
OSI, Philips-Advance and GE T8 265mA Programmed rapid start ballasts in their current catalog supports F17 to F32, so presumably, the pre-heat stage voltage is low enough to ensure proper sequenced starting of F17.
I've not reverse engineered them, so I don't know how they're actually constructed. You don't have a basis to claim "most" based on a few sample designs from IRF ballast IC and such.
You Europeans often do things different too. The US ballasts I'm familiar with have the cathodes on interconnected side of lamps in parallel, while some European design often have them in series, but I don't claim to know the "most" common procedure for EU spec ballasts.
Statistically, based on commerce data, >70% of "electronic ballasts" sold in the US are cold-start instant-start (no power to cathode heaters at all).
Jace the Gull:
I have a Motorola Rapid start Electronic ballast (it actually acts more like a programmed start) It rated for F32T8, F25T8 and F17T8.....I am currently using it to run an older (circa 50's) Champion F30T8 (3 foot) lamp. It works well...
I also did a test on that same ballast with a HO lamp...a F24T12 OH that is 35 watt...it powered it up without problems!!!
Maybe you got some info?
Adderall:
--- Quote from: GullWhiz on June 05, 2010, 10:34:18 PM ---I have a Motorola Rapid start Electronic ballast (it actually acts more like a programmed start) It rated for F32T8, F25T8 and F17T8.....I am currently using it to run an older (circa 50's) Champion F30T8 (3 foot) lamp. It works well...
I also did a test on that same ballast with a HO lamp...a F24T12 OH that is 35 watt...it powered it up without problems!!!
Maybe you got some info?
--- End quote ---
The issue with under-driving is once its started, but since its a rapid start with cathode heat power, the cathodes don't sputter by under-driving the lamp. You've basically placed the lamp into service as if it was put into a dimming ballast and dimmed it down. Since normal Motorola ballasts are designed to power lamps at 85-87% (give me the model # and I'll check the specs in my catalog...)
0.36A lamp on a ballast designed to run a 0.265A lamp at 85% output will probably give around 70% of rated output. The HO lamp would also work, but waaay dimmed from rated output.
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