Lighting-Gallery.net
General => General Discussion => Topic started by: irpyc on November 14, 2011, 03:09:25 PM
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Sorry for another neeb topic, but i want to buy somes ellectronic ballast, and i don't really understand differences of ballasts.
Sometimes ballast can run different kind of tube, but sometimes not. What is the difference beetwin PLL, T5, T8, or T12 ?
I know T5 and pll can have only electronic ballast, but why ?
Can i use PLL tube on any T8 ?
Can i use lower power tube on higer ballast ?
I don't find ballast for T12 48" 75w tube ? 2x58 T8 ballast ?
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It probably comes down to :
Same power at different current / voltage. Just example 36W can be 72V 0.5A or 144V 0.25A which is same power but 2 totally different tubes and ballasts. Running one of them on a ballast meant for the other one will over/under power it quite a lot
Cathode preheating differences. Some cathodes are meant for preheat at higher current then no heating (switch / programmed start), some for continuous light heating (RS), etc
Also some PLL and T5's in fact do work on magnetic switch start. I even managed to run a spiral tube from a 20W CFL on switch start and it worked well
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No question
Sorry for another neeb topic, but i want to buy somes ellectronic ballast, and i don't really understand differences of ballasts.
Sometimes ballast can run different kind of tube, but sometimes not. What is the difference beetwin PLL, T5, T8, or T12 ?
I know T5 and pll can have only electronic ballast, but why ?
They are rated for electronic ballast, but that does not mean they could not be run on series choke.
The series choke is limited for lamps with arc voltage below half of the mains, otherwise the arc may be unstable or you would have troubles to find a suitable starter.
So lamps rated for magnetic ballasts followed the rule of maximum ~120V arc voltage.
With high frequency electronic ballasts there is no direct link to the mains voltage, as the ballast circuit may generate virtually any voltage the lamp need, so these T5 and PLL have frequently arc voltages above the 120V (some even 210V).
The preheat current is usually rated for double the nominal arc current for ~1 second preheat time, this is independent of the ballast type (the filament have long inertia, so the frequency does not matter at all). Series magnetic chokes provide usually 1.5x nominal current during the preheat, what correspond to 2 second preheat time. This is fulfilled by most starters.
Can i use PLL tube on any T8 ?
Not on "any" but on the corresponding one yes. Most important is the ballast current (should be -30..+10% from the lamp rating) and (the sum of) arc voltages should not exceed 1/2 of the mains voltage, so:
- PLL18 could be run on the same as F18T8 (single on F18T8 and series pair on F36T8)
- PLL24 only single on F18T8 ballast. Could be combined in series with PLL18W on the F36T8 ballast (but not two PLL24W, as these would have too high combined arc voltage)
- PLL36 and PLL40 same as F36T8 (only single)
- PLL55 on F58T8 ballast
- PLL80W have too high arc voltage for 230V mains
- F4T5 and F6T5 may work on PL-S 5..11W, but only in series pairs (otherwise they would be overdriven)
- F8T5, F13T5 and F14T5 on PL-S11W ballast (F8T5 may work in pairs, otherwise only in single)
- F24T5 and F39T5 on F18T8, only single, the F39T5 would be underdriven
- F54T5 on F36T8, but would be underdriven
- Other T5 have too high arc voltage for 230V mains
When operated as single, the correct starter would be S10 or equivalent (so rated for at least "20..65W" range), when in series pairs, the correct starter would be S2 (so rated "4..20W")
Can i use lower power tube on higer ballast ?
The ballast current have to match, the arc voltage should not be too low for the ballast, as it may overheat. So except special cases, generally no.
I don't find ballast for T12 48" 75w tube ? 2x58 T8 ballast ?
I don't know the current rating for the F75T12, but I guess it would not be more then 0.8A, so pair of F58T8 ballasts would be way too much.
For the 0.8A pair of F36T8 or a single MV80W (yes, ballast for mercury vapor HID lamp) would be fine, but better to check.
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Ok, thanks a lot Ash and Medved
So i can use PLL on T8 if same wattage.
I principaly use PLL and T8, and maybe i will use T12.
I ofthen use 36w PLL on a fixiture with Clalight Unitronic T5 ( CLT_WS_2S54_230_KH), so that bad ?
what did you mean by "PLL36 and PLL40 same as F36T8 (only single)" ? I have somes 2x36 TL-D /T8 ballast, i can't run 2x 36w PPL 2g11 ?
For T12, i woul'd like to run 75 F40T12CIN32HOCVG (http://genet.gelighting.com/LightProducts/Dispatcher?REQUEST=COMMERCIALSPECPAGE&PRODUCTCODE=15782&BreadCrumbValues=Lamps_Linear%20Fluorescent%5EStage%20_,%20Studio&SearchFieldCode=null)
Why not a T5 80w or a T8 70w ?
For two 36w, in serie or paralel ? A 236 coul'd work ?
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Single means one lamp on each ballast output. So you can run 2 36W PL's on a ballast intended for 2 36W T8's, each connected as a T8 would
With smaller lamps you can run 2 lamps (sometimes even more) on the same balast output in series, such as 2x 18W lamps on 1 1-lamp 36W ballast
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The alternatives I described above are valid only for magnetic series choke ballasts (the most common magnetic concept in Europe), what I've never seen to be designed for more then one lamp circuit (so either one lamp, or series pair), as these ballasts are only a simple inductor.
More then a pair in series is not used, as there are no suitable starters for that configuration (the mains voltage may be too low to reliably trigger three starters in series)
Other ballast types (any starter-less, electronic, the one you can not determine,...) should be used only with the designed lamp. You have to exactly know the individual ballast design (heater concept and connection, output characteristic, long term safe operating area,...), in order to determine it's suitability for different lamp. Mainly electronic are dangerous, as they generally light up any lamp somehow (so appear working, even without apparent overheating), but when mislamped, either the ballast, or the lamp may suffer from quick degradation and failure (e.g. the operation of T5 on T8 ballast frequently overstress the resonant capacitor, as ignition voltage for T5 is higher then T8.).
Generally underpowering the lamp a bit (about the same arc voltage, but operate at down to 70% of rated lamp current) does not hurt so much, the lamp would only not reach the full rated brightness.
Series choke (magnetic) can operate with higher arc voltage lamp then designed for, only the "maximum 50% of mains" rule have to be followed.
But unless you are familiar with the inner workings and have the tools and skills to check the operating conditions, do not do any experiments with electronic ballasts, if you want some reliability from them, do not rely on the protection circuit to shut it down, it is designed only for some faults of the specified lamp, not to protect the ballast against damage when mislamped.
Classic series magnetic cokes are quite immune, as worst case the lamp would not start or it would be flashing or so.
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Ha ok, this if for choke ballast.
I was most thinking about electronic (lightwheit, HF is better for eyes and anti flicker) and i'm aslo interested by dimming ballast, that rare in magnetic.
But yes i shoul'd retrieve somes magnetic ballast (easy to find in the street, cheap), it's more universal.
And what about tungsten lamp in serie ? Witch lamp i need ? 110v lamp ?
But unless you are familiar with the inner workings and have the tools and skills to check the operating conditions, do not do any experiments with electronic ballasts,
Ok !
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Magnetic series inductor (switch start) on standard triac dimmer :
Will dim for a bit, then lamp drop out and go flashing if left like that for a while. If many lamps (on separate ballasts) installed in parallel, each will drop out at somewhat different time (differences between lamps), which IMHO is quite nice sight (seen it done in a hall)
Magnetic Rapid Start ballast :
Never tried it, but i think that if you separate the supply for the preheat transformer and the actual ballast, and put the dimmer only on the ballast, possibly you'll even get quite good results
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And what about tungsten lamp in serie ? Witch lamp i need ? 110v lamp ?
Always use 230V lamps, the 120V would be overdriven (you would need incandescents rated 160..200V for filament temperature, but full 230V dielectric strength to avoid arcing)
Incandescents are technically a resistive ballast, what have one drawback: It can not provide higher voltage then mains peak value and they keep the lamp without discharge for long time, when the mains voltage sinewave have lower voltage then the lamp arc voltage.
Each time the current trough the lamp drops, the arc extinguish and it should reignite as soon as possible with the other polarity. As current zero cross on series choke ballast lag behind the mains voltage, there is quite significant voltage already present there for the reignition, boosted by the ringing from the ballast inductance and capacitance in the starter (forming a resonant circuit). So the arc reignite only few 100's us after it extinguish, after that time the ionisation level in the lamp does not fall, what support the reignition, so not as high voltage is needed.
With resistive ballast the mains voltage is about in phase with the current, so remain low, when the lamp extinguish. And it take ms till the voltage reappear, during this time the ionization level drop a lot, so the lamp need nearly the full igntion voltage for the reignition, delaying this farther into the sinewave. The current flow through the lamp for shorter time, what mean higher current crest factor as a result.
If some lamps have too high arc or reignition voltage, it does not reignite at all, so it is not able to light with the resistive ballast.
Older argon tubes (FCxT9, T12, F15T8,...) and low arc voltage krypton (F18T8) work quite well, even with a glowbottle starter, but only as single lamp with the higher trigger voltage starter (S10,...).
Newer krypton tubes (F36T8..F58T8, PL-S,...) work only with manual start (or they may work with thermal starter responding to circuit current and not arc voltage).
Modern T5 would have troubles due to high required voltages for start and even reignition after zero-cross, I guess, but I didn't tried them.
With ballasting lightbulbs you have to experiment a bit, start with a bulb with normal current about 1.5x the nominal lamp current and measure the result.
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Newer krypton tubes (F36T8..F58T8, PL-S,...) work only with manual start (or they may work with thermal starter responding to circuit current and not arc voltage).
What did you call manual start ?
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Push button in place of the starter
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Ho yes it's working... it's fantastic !!
Lightwheit, silent, cheap and dimmable
But i succes only on T12, not on F58T8, filaments are warming and illuminate, but the tube stay off.
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Still might work with shorter T8
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You have to have sufficient current for preheat and s patience with starting them - it require several attempts.
Try to connect the lamp on the phase side and put grounded metal along it. The field between electrodes and the grounded metal create some ionization during preheat, what then help for ignition.
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Why would it matter on which side of the AC the lamp is ? Unless it is struck the potential (vs earth) after the ballast is same as without it
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It is not about voltage between one and second filament when the starter switch is OFF, but about voltage between filaments and the external (grounded) metal work, when the starter switch is still ON
During the preheat (starter switch is ON), both ends are on the same potential, as they are shorted together by the starting switch.
Assume the metal part close to the lamp is grounded.
So if the lamp is on the neural side, the filaments are on the neutral potential during the preheat. So there is no voltage between the electrodes and the metal outside the tube, so only electrodes get heated during the preheat. So only when the starter switch open, the voltage between tube ends start to develop a ionisation.
But when the lamp is on the phase side, both filaments are on the phase potential, what mean you have the mains voltage between filaments and the external metal parts. This form a discharge with one direct inner electrode (filaments) and one capacitive coupled outer electrode (the grounded fixture metal body/reflector/...)
This discharge is nearly not visible (maybe in the dark as tiny glow progressing from tube ends; this effect become quite bright on HF), but as it is ionisation at the end, so when the starter switch open, there are already many ions present to start an avalanche into full arc between both tube ends.