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Author Topic: Dimmable CFL's in the auditoriums Bruce McGee Phenomenal Film Handler Posts: 1776 From: Asheville, NC USA... Nowhere in Particular. Registered: Aug 1999 posted 08-18-2008 05:53 PM                     I installed dimmable CFL's in a small auditorium today. Our automation dimmers are the old SCR/Triac type. I cant get the lights to dim more than about 30% even with the setting on the automation turned all the way down. At the down setting, the regular lights would be out. The auditorium is still lit too much. What are you guys doing to remedy this problem? I cant just turn them off without being there when the movie ends. I sure dont want a customer to fall or something worse because we have to turn the lights off!  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 08-18-2008 07:39 PM                     I've done ALOT of work on dimmable florescent systems.... almost too much. The lowest you can go is 5% before wierd things start to happen and this requires some pretty specialized florescent related gear to accomplish. If you lamps flash and flutter before extinguishing the way to cure that is to set the dimmer low level cut off to occur just before the flutterin and a blinkin occur. As the lamps age they will also begin to dim to different low level amounts before they flutter and go out. It also requires special ballasts and dimmers to do the job properly... which in my book still isn't even working properly nor will it ever be able to dim down to 0%. Both Strand, and Colortran (now owned and totally fucked up by Leviton) make the special dimmer modules. Many ballast manufacturers make the ballasts which are solid state. I don't recommend any of it. The power you saved will be spent in special lamps and ballasts during the life of the building they are in. Low voltage lighting I feel would clearly be the wiser choice. Probably the biggest florescent farce on record occurred in Cineplex theaters during their last major builds here in the U.S. They installed florescent lights in all auditoriums at all locations(that I know of) connected to those Stanley Ash Canadian Made Dimmers... when you went to dim em down you got a nifty light show as they strobed on and off, flashed, fluttered, like CE3K! Then they finally went out. Can't blame the dimmers for it though.. they weren't made to do it. The dimmers could have been modified for a low cut off point at around 30% which is where the fluttering started to happen. A simple relay that would drop out the dimmer at 30% would have been a very easy fix for these locations. Edit: Oops! Left out an important trait of florescents and that is they tend to glow for a while after they have been turned off . Also see Dimming Florescents Mark  |  IP: Logged Bruce Hansen Jedi Master Film Handler Posts: 847 From: Stone Mountain, GA, USA Registered: Dec 1999 posted 08-18-2008 09:40 PM                     You might try putting one incandescent lamp in each dimming circuit. This will give the dimmer a more stable load to look into. It may help a little. I don't care what the manufactures say, gas discharge lamps are not really dimmable.  |  IP: Logged Paul Mayer Oh get out of it Melvin, before it pulls you under! Posts: 3836 From: Albuquerque, NM Registered: Feb 2000 posted 08-18-2008 10:17 PM                        CFLs haven't worked well for me either. I've been looking for dimmable room lighting that will draw much less current than what I'm currently using in my portable projection setup. Even with available fluorescent dimmers and dimmable ballasts the lamps only go down to about 1/3 brightness, then they cut to black. When I bring them up, even when starting from zero, they snap on to about 1/2 brightness. It's just not a good enough result, given what it cost to assemble and try this system. Might as well just turn the lights on or off - not very professional. I went back to my original setup - halogen scoops pointed up to bounce light off the ceiling, controlled by a regular triac dimmer. Just have to have a separate 15-amp circuit to power it. When I recover from the cost of this failed CFL experiment, I next want to look at LEDs and PWM dimmers as a dimmable room lighting solution. More research.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 08-19-2008 08:30 AM                     quote: Paul Mayer When I recover from the cost of this failed CFL experiment, I next want to look at LEDs and PWM dimmers as a dimmable room lighting solution. More research. As I mentioned above there are florescent lamps and ballasts that when used in conjunction with the proper dimmers can dim down to 5%. And yes they do pop on and off at that level then dim up or down. Many LED's have similar characteristics as florescents do... in other words they are only dimmable to a certain extent. The best answer is still low voltage lighting which is completely dimmable. Mark  |  IP: Logged Jim Cassedy Phenomenal Film Handler Posts: 1661 From: San Francisco, CA Registered: Dec 2006 posted 08-19-2008 10:04 AM                     I had a theater employee install a CFL in a rear wall sconce that was connected to an older type autotransformer dimmer. Later, the bottom of the CFL totally melted and began to smoke before shorting out as the electronic ballast overheated. I was able to get some consumer grade CFL's to work on an electonic dimmer circuit at my home by installing at least one standard incandescent on the same circuit as someone else mentioned here. I think the incandescent works as sort of a 'ballast' so the electronic dimmer sees a constant load. Since CFL's are not in a 'constant-on' state, and the dimmer works by altering the current duty-cycle, without the incandescent all my CFL's would do was to strobe. A nice effect- - but not what I wanted.  |  IP: Logged Frank Angel Film God Posts: 5305 From: Brooklyn NY USA Registered: Dec 1999 posted 08-19-2008 10:46 AM                        quote: Mark Gulbrandsen Oops! Left out an important trait of florescents and that is they tend to glow for a while after they have been turned off. AND, they don't come to full brightness until a good minute, minute & half after they are brought up to full. As far as being dimmable (the ones that say they are made specificially for being able to be dimmed -- forget about the standard ones) it's a joke. THEY SUCK. I didn't do the extensive experimentation that Mark has done on them, all I needed was to have a slew of them either overheat and smoke to death like Jim's, or even when they did work down to that totally unacceptable 25, 30% blink out level, they would die prematurely. CFLs, even when they don't go up in smoke on you are much too unreliable (some of ours even in regular non-dim service die very early on). The only way CFLs will work in dimming situations with the same effectivness as incandescents, is if they are in fixtures like they have at Radio City Music Hall -- fixtures that have an iris and a small motor controlled by the DMX signals from the lighting console. The iris is what dims the light, not the light source. Such a fixture doesn't have to be elaborate, just an enclosure and a simple vane that can be opened and closed by a micro motor. Yah, it could be done, but there goes any savings you might get from using CFLs, no matter how inexpensive they could make such a fixture.  |  IP: Logged Demetris Thoupis Phenomenal Film Handler Posts: 1240 From: Aradippou, Larnaca, Cyprus Registered: Apr 2001 posted 08-19-2008 11:40 AM                     0-10 Ballast dimming DMX Dimming DALI dimming That is the way if you want to actually DIM fluorescents. You will require a special type of dimmer of course (Lutron makes the GXI31xx series if you want which dims 4 circuits of fluorescent). The lowest you might be able to get them is around 7-10% and then they switch off. Different manufacturers offer better ballasts. You might find fluorescents which switch off at 30 or even 40%. It depends on the manufacturer and especially in auditoriums, it's not really worth it. Go for 3 runs of rope light instead. Demetris  |  IP: Logged Bruce McGee Phenomenal Film Handler Posts: 1776 From: Asheville, NC USA... Nowhere in Particular. Registered: Aug 1999 posted 08-19-2008 06:04 PM                     I tried the idea of leaving a standard lamp in the circuit. In fact, I tried one regular lamp on each side of the theatre. Doesent work. I'm sure when the higher-ups in my company get wind of these problems, something will change. Its odd how the CFL's continue to glow even when the standard incandescents are completely dark. I'm sending this thread to my tech. Thanks Guys!  |  IP: Logged Bill Enos Film God Posts: 2081 From: Richmond, Virginia, USA Registered: Apr 2000 posted 08-19-2008 07:05 PM                     I've tried supposedly dimmable compact fluorescents on both resistance and electronic dimmers with the same result---they dim about 20% and blink off.  |  IP: Logged Lyle Romer Phenomenal Film Handler Posts: 1400 From: Davie, FL, USA Registered: May 2002 posted 08-20-2008 10:37 AM                     Dimmable LEDs could be designed that shut off parts of the led array for different light levels instead of dimming each led. You could design a fixtue that lets say has 100 LEDs in it and then turns one off for each 1% in dimming. You could do something similar with multi-element CFLs but the bulb would be very expensive.  |  IP: Logged Robert Minichino Master Film Handler Posts: 350 From: Haskell, NJ, USA Registered: Dec 2005 posted 08-20-2008 12:19 PM                        But PWM LED dimmers are 90+% efficient and you save the extra wire you'd need to make banks of LEDs. LEDs themselves can be modulated continuously from total dark to full-on with no loss of efficiency and little change in color temperature.  |  IP: Logged Mike Blakesley Film God Posts: 12767 From: Forsyth, Montana Registered: Jun 99 posted 08-20-2008 07:58 PM                        I've now seen floodlight bulbs that have those twirly bulbs built in....would love to use those in the theatre ceiling but would be leery of how they would behave (or misbehave) with the dimmer.  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 08-20-2008 09:44 PM                     I have recently installed a fair number of dimmable CFL made by U Lighting America They dim smoothly on standard triac and SCR dimmers to 430volts RMS and then flicker and go out Bruce what make of dimmer do you have some require an adjustment to the trigger ramp circuit depending on load type and amount  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 08-20-2008 10:24 PM                     quote: Gordon McLeod They dim smoothly on standard triac and SCR dimmers to 430volts RMS and then flicker and go out Well, all the dimmable florescent systems I've worked with do indeed dim smoothly down to where they start to flicker... but they are not supposed to flicker before they go out, they should simply go out right before that flicker begins to happen. Many dimmers just make use of a small contactor to disconnect the lamp from the dimmer just before that flicker point. Some are adjustable and some not... some dimmers are very ballast and lamp specific. Mark  |  IP: Logged

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