WorldwideHIDCollectorUSA
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HID, LPS, and preheat fluorescents forever!!!!!!
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| Since I have seen that many North American 120v F20T12 preheat fluorescent tube series choke ballasts are also listed to run other types of lower power fluorescent tubes, I have often seen that they run F20T12 fluorescent tubes at roughly 75-80% of their rated power but sometimes run the lower power fluorescent tubes at full power such as F15T8 fluorescent tubes and F14T12 fluorescent tubes.
I have seen some people say that underdiving HID lamps under any circumstances will reduce their lifetime and in other cases, some people have said that underdriving HID lamps will prolong their life under certain operating conditions.
What are your thoughts of running 100w H38 mercury vapor lamps on 75w H43 mercury vapor HX autotransformer ballasts, 100w M90 pulse start metal halide lamps on 70w M98 pulse start metal halide HX autotransformer ballasts, and 100w S54 high pressure sodium lamps on 70w S62 high pressure sodium series choke ballasts and HX autotransformer ballasts to acheive a lower ballast factor for the lamp?
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Desire to collect various light bulbs (especially HID), control gear, and fixtures from around the world.
DISCLAIMER: THE EXPERIMENTS THAT I CONDUCT INVOLVING UNUSUAL LAMP/BALLAST COMBINATIONS SHOULD NOT BE ATTEMPTED UNLESS YOU HAVE THE PROPER KNOWLEDGE. I AM NOT RESPONSIBLE FOR ANY INJURIES.
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joseph_125
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| Bi-level operation of HID lamps on magnetic HID ballasts was something allowed by some ballast manufacturers as a means to save energy. It took advantage of the fact that lamp current could be modulated by manipulating the effective capacitance on a CWA type circuit. For bi-level you'd have a secondary capacitor wired in series or parallel with the primary capacitor which would be switched in and out of circuit to reduce the lamp current.
Advance recommended no more than a 50% reduction in lamp power or around 0.50 BF and that the lamp be operated at full power during startup and the first 15 mins to allow for the lamp to fully warm up prior to reducing the lamp power. In theory one could probably do the same for a 20-25% reduction in lamp power with alternate capacitor values but it seems like it was recommended to allow the lamp to fully warm up on the correct drive current prior to dimming which can't be achieved on simply using a lower wattage ballast.
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sol
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| Thank you both for bringing this up as it is on my bucket list of things to do when time permits....
I have some M57 ballasts and lamps with which I would like to try this. The ballasts are CWA, so it should be quite easy.
I also have a 70W M98 lamp on a HX ballast (with remote ignitor) that I would like to dim down to about 50%. However, colour and CRI are very important because I use it for living room lighting, so I will have to do some research/experimenting with that one.
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RRK
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Roman
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| @sol:
Dimming a MH lamp is generally not a good idea when you care about light quality. You can go to about 60-70% with some lamps , but in most cases you end up with greenish light. Sometimes done in streetlighting when CRI is not as important. There is a rare kind of Philips 'lightboost' series of CMH that is rumored to perform acceptable when dimmed.
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WorldwideHIDCollectorUSA
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HID, LPS, and preheat fluorescents forever!!!!!!
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| I am also wondering if there is a way to dim fluorescent tubes and non integrated CFL lamps operating on preheat fluorescent tube ballasts in a safe manner.
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Desire to collect various light bulbs (especially HID), control gear, and fixtures from around the world.
DISCLAIMER: THE EXPERIMENTS THAT I CONDUCT INVOLVING UNUSUAL LAMP/BALLAST COMBINATIONS SHOULD NOT BE ATTEMPTED UNLESS YOU HAVE THE PROPER KNOWLEDGE. I AM NOT RESPONSIBLE FOR ANY INJURIES.
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RRK
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Roman
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| For dimming fluorescents, you are just increasing the impedance of the ballast - like inserting additional series choke in the circuit. At some time (probably around 50% of the intended power) self heating of the filaments will start being not enough for thermal emission and you will start to lose tube lifetime catastrophically. This can be cured by adding heater transformer exactly like the rapid start circuits do. That way you can go to zero discharge current without lifetime penalty. Inserting a phase dimmer in a series with a choke will work too, though you will get annoying flicker at the low end of brightness. A very old school way to fix this (from 1970s) to fix this was to add a high frequency 'bias' to the lamp current.
Actually, today the most fun way to play with fluorescent dimming is to get an intelligent dimming electronic ballast with 1-10V control. Me and my friend had great fun making a 'light organ' circuit that plays dynamic effects on the music with RGB colored T8 36W fluorescents and Osram dimming ballasts. Worked very well. It was my childhood dream actually, but was too complicated in that time, and color tubes were hard to get, but today was possible to be done with off-the-shelf components.
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« Last Edit: June 16, 2023, 08:42:32 PM by RRK »
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WorldwideHIDCollectorUSA
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HID, LPS, and preheat fluorescents forever!!!!!!
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| I also wonder if I can add impedance on HX autotransformer ballasts or series choke ballasts designed for HID lamps to dim them as well using that same technique.
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Desire to collect various light bulbs (especially HID), control gear, and fixtures from around the world.
DISCLAIMER: THE EXPERIMENTS THAT I CONDUCT INVOLVING UNUSUAL LAMP/BALLAST COMBINATIONS SHOULD NOT BE ATTEMPTED UNLESS YOU HAVE THE PROPER KNOWLEDGE. I AM NOT RESPONSIBLE FOR ANY INJURIES.
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RRK
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Roman
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| Yes, sure you can. In a circuit theory, leakage transformer is transparently modeled as an ideal transformer with a series inductance. Be careful with CWA circuits, there are complexities because of resonance and non-linear effects. You also can add a series choke even at the primary side of a regular leakage transformer, but remove PFC capacitor in that case to avoid resonance.
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« Last Edit: June 16, 2023, 08:52:23 PM by RRK »
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RRK
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Roman
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| One particular thing to be careful if you are playing with HID circuits that way is to be sure the ignitor will still have a high frequency path to the lamp to work, and in case of semi-parallel circuit, also a high frequency path to tap of the ballast winding. Superimposed ignitor will work with no problem if connected right to the lamp.
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joseph_125
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@sol - For M75/175w MH, (ballast family 71A55_0) the Advance recommended capacitor configuration is to have a 40µF 300V secondary capacitor in series (see wiring diagram) after the 10µF 400V primary capacitor with a switch or relay wired to bypass the secondary capacitor. On full, the effective capacitance would be the expected 10µF, on low the effective capacitance is listed as 8µF. Using a timer relay, you can probably automate the dimming to kick in after 15min of operation following recommendations OR to enable the dim switch after 15min. I've attached the chart of recommended capacitor/ballast pairs for bi-level operation as well as the older Advance catalogue I got it from. I like the using the 2002 edition for looking up info on older ballasts as it still listed a lot more of it compared to newer catalogues. For 70w M98/C98, I'd honestly look into eHID (electronic HID) dimming ballasts and wire it up with a 0-10V control. It would probably be the easiest off the shelf method to dim such a lamp. This one supports 50%-100% full range dimming using 0-10V dimming which I suppose is fairly standard since it's not advised to dim HID lamps that extremely. |
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RRK
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Roman
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| A relay/switch here will have a very hard time working, because it switches large capacitors at high voltage with high surge current. Need to be a very heavy duty type!
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WorldwideHIDCollectorUSA
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HID, LPS, and preheat fluorescents forever!!!!!!
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| Would another way to dim fluorescent lamps on preheat circuits and magnetically ballasted HID circuits include wiring a number of series choke ballasts in parallel and adding a switch for each choke ballast to adjust the light level?
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Desire to collect various light bulbs (especially HID), control gear, and fixtures from around the world.
DISCLAIMER: THE EXPERIMENTS THAT I CONDUCT INVOLVING UNUSUAL LAMP/BALLAST COMBINATIONS SHOULD NOT BE ATTEMPTED UNLESS YOU HAVE THE PROPER KNOWLEDGE. I AM NOT RESPONSIBLE FOR ANY INJURIES.
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RRK
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Roman
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| Generally yes, though you are not very clear with the term 'series choke in parallel'. You better start to draw some schematics.
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WorldwideHIDCollectorUSA
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HID, LPS, and preheat fluorescents forever!!!!!!
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| For some reason, it’s hard to post any schematic drawings in the forums since the camera that my photos take have a significantly larger file size than is allowed here.
L——- Switch 1 ——— choke 1--------————-|
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| ----- Switch 2 ----- choke 2 -————--| |
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N———————————lamp——————————————-|
Can you understand this typewritten circuit diagram better?
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Desire to collect various light bulbs (especially HID), control gear, and fixtures from around the world.
DISCLAIMER: THE EXPERIMENTS THAT I CONDUCT INVOLVING UNUSUAL LAMP/BALLAST COMBINATIONS SHOULD NOT BE ATTEMPTED UNLESS YOU HAVE THE PROPER KNOWLEDGE. I AM NOT RESPONSIBLE FOR ANY INJURIES.
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RRK
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Roman
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| Yes, will work perfectly.
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