Gallery of Lights
Questions On The Code => General Discussions on Code => Topic started by: rjluna2 on February 25, 2010, 01:19:07 PM
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I understand that both HO and VHO (SHO at other marketing) are rated 800 mA and 1500 mA respectfully.
I am wondering about the standard T12 and T8 tubes. Do they have separate current ratings? Correct me if I am wrong, the F40T12 have the current rating of 465 mA and the smaller T8 bulbs are around 260 mA. Comments?
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I have some data on current and voltage I found in Philips data sheets and compiled to a list a while ago. T8 is for European tubes. (but I think the T5 ranges are the same all over the world)
-T8
15 W
51 V 340 mA
18 W (compatible with 20 watt T12)
59 V 360 mA
30 W
98 V 360 mA
36 W (compatible with 40 watt T12)
103 V 440 mA
58 W (compatible with 65 watt T12)
111 V 670 mA
-T5 Miniature
4 W
29 V 170 mA
6 W
42 V 160 mA
8 W
56 V 150 mA
13 W
90 V 170 mA
-New T5 tubes (170 mA = HE tube, otherwise HO):
14 W
83 V 170 mA
21 W
125 V 170 mA
24 W
80 V 300 mA
28 W
166 V 170 mA
35 W
208 V 170 mA
39 W
119 V 330 mA
49 W
195 V 255 mA
54 W
118 V 460 mA
80 W
151 V 540 mA
I don't understand why the product of the current and voltage isn't closer to their wattage, but these were the numbers given.
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@f36t8: The product is about 11% higher then wattage (PF = 0.9), because of shape mismatch between voltage and current on most series-choke ballasted discharge lamps:
Current is nearly sinusoidal, but voltage square-wave, what yield power factor sqrt(8)/Pi = 0.9
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I have a copy of IESNA Lighting Handbook 5th (1972) & 9th (2000) edition. If you have specific questions regarding US spec lamps, I'll gladly look it up.
F40T12 is listed as 430mA, at least in N.A. or ANSI. IEC may differ slightly.
F17T8, F25T8, F32T8, F40T8, F96T8 and their energy saver counter parts are all 265mA.
The old generation T8s like F15T8 and F30T8 are different.
The nomenclature is antiquated and is full of problems. Only the suffix tell you something definitively.
New generation T5s are not even listed in my books :(
FxxTyy y=n/8 inches bulb diameter
xx could mean nominal length,watts or meaningless. It only gets worse with emergence of energy saver lamps.
F25T8 is a 25W nominal 24" lamp.
Now there is a new type that is 48", 25W Energy Saver intended to retrofit F32T8 48". The nomenclature differs between brands. F32T8/XEW is Philips nomenclature for 48" nominal, medium bi-pin 265mA 25W energy saver lamp. The 32 doesn't mean squat.
F34T12 is the generally accepted notation for 48" T12. 34 means the watts here.
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I have a copy of IESNA Lighting Handbook 5th (1972) & 9th (2000) edition. If you have specific questions regarding US spec lamps, I'll gladly look it up.
F40T12 is listed as 430mA, at least in N.A. or ANSI. IEC may differ slightly.
F17T8, F25T8, F32T8, F40T8, F96T8 and their energy saver counter parts are all 265mA.
The old generation T8s like F15T8 and F30T8 are different.
New generation T5s are not even listed in my books :(
I will be really interested to hear! Thanks!!!
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I will be really interested to hear! Thanks!!!
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.
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@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.
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@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.
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).
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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?
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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?
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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Catalog number is... the Model is M1-RN-T8-1LL-120
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Catalog number is... the Model is M1-RN-T8-1LL-120
Ballast Factor 0.875±0.025
M1-RN-T8-1LL-D-120
F32T8 32 120v 0.26a 31,30
F25T8 25 120v 0.21a 25,24
F17T8 17 120v 0.16a 19,18
The two numbers on end are input wattage. First one is open fixture, second is enclosed. The wattage difference is due to lamp temperature difference.