I look around on the Bay for theses Sola CVS but didn't see any info about the max watts. What about the "sine wave output" ex: 23-23-210-8 or 23-22-112-2 ?
My intention is to use this kind of unit for stabilize compact fluorescent photo bulbs, mine are 45W , 5,600K, generally a shooting set-up of 8 to 10 bubs = 360-450 Watts total.
The Sola ID plates list the output capacity in V.A. for Volt-Amps. Volt-Amps are equivalent to Watts if the load is essentially resistive, like an incandescent bulb. Where the load includes significant net reactance (inductance or capacitance) there is a phase difference between the voltage and the current. Then the power consumed (Watts) is the voltage x the current x the cosine of the phase angle. This means that for a reactive load, the V.A. needed will be higher than the power consumed. Given the ballasts used in fluorescent fixtures, they may be significantly reactive. (I don't know - somebody else here might.)
It might be easiest to just measure the current drawn by your lighting set up and multiply by the voltage to find the V.A. capacity you need.
Thanks you for trying to explain to me but "cosine of the phase angle" is like Chinese for me. Electricity is not my domain at all.
First question : if Compact fluo lamps are "reactive", it will serve nothing to try to stabilize it ??
Second question: I don't have any idea how to mesure my lighting set-up
This is what I have: 3 softboxes like this http://www.lincoinc168.com/brpe4xfllihe1.html
and the Sola unit is this one: Sola Constant Voltage Transformer , Catalog No.: 23-13-030-2, Harmonic Neutralized Type CVS, Input V. 95-130, Freq. 60Hz. Va. 30 (item #120449489578 on the Bay)
Is any one use this kind of lamps for shooting?
Maybe the wrong forum for this but the Voltage Stabilizer discussion made me think about trying to solve the color variation I observe using theses lamps. I used it only on digital, still not have test it on film.
The lights you linked require 160 watts for each box (four 40-watt fluorescent fixtures). Three of those is 480 watts. A 750VA power conditioner will be fine, even if the fluorescent fixtures are reactive with a reduced power factor (which I just don't know).Originally Posted by Ginette
First question : if Compact fluo lamps are "reactive", it will serve nothing to try to stabilize it ??
Second question: I don't have any idea how to mesure my lighting set-up
The "560 watts" in parentheses in the listing is intended to provide the wattage of incandescent lighting that would provide the same light output. 40-watt compact fluorescents are usually compared to 140-watt bulbs in terms of light output.
Rick "wondering what color correction these would need" Denney
Being a reactive load does not imply that stabilization is not useful.
Each of your of your softboxes light will require 160 Watts. Sources on line (You know how reliable they can be.) estimate the power factor for compact fluorescents to be as low as 0.6. These figures imply that you need a capacity of 3*160/0.6 = 800 Volt Amps or greater. That Sola has an output capacity of only 30 Volt Amps and will not do.
Thanks, this is more clear now.
This will be quite big and heavy. I look at models and their VA on their website
Will 3 smallers units (one on each sofbox) do the same job ? Even if they all on the same circuit (hope it is the same term in English than French!)
Nice bargain, can you indicate me the item number that I look your model.
Here is the item that I bought 180373725418. I had noticed that they seem to no longer have a 750 VA model in their line. It is a beast.
Three smaller units should work, but like Rick I am wondering exactly what color correction you need. I am not sure that fluorescents change color with voltage fluctuations the way that incandescents do. Their (frequently poor) color seems to be determined by the phosphors that are used. The pernicious thing about power fluctuations in the darkroom is their unpredictability and the need to redo prints. When shooting digital, you should be able to notice the problem, either by eye at the time of the exposure or by reviewing the captured image immediately after, then re-shoot immediately with little trouble. (Said just like somebody who does not have to put up with the problem.)
This sort of power conditioning requires large transformers, and they are indeed big and heavy.
The 1000VA model, considering a .6 power factor, would supply 600 watts continuous for compact fluorescent fixtures (the Sola models will handle momentary surges well above their rated output). That would be fine for the 480 watts consumed by three of the units you linked.
There is a 750VA model in the portable units, and I would definitely recommend that you use a portable unit. The hardwired units you linked will require installation by a qualified electrician. The 750VA model will be marginal with those lights at a .6 power factor, providing 450 watts instead of the required 480. But I'll bet they would handle it. And you should investigate the actual power factor of those fixtures--they might not be quite as bad as .6.
To power one of these fixtures, you need a 267VA supply. Again, their 250 might be sufficient, especially if the power factor is even a little higher than .6. But running 3 of the 500VA models would be less efficient than running one 1000VA model.
According to the specs, the 750VA model will draw about 9 amps, and the 1000VA model will draw about 12 amps. A typical branch circuit in a house is designed to supply 15 amps, so it should have no problem, as long as that branch isn't sharing the circuit with something else that is pulling very much current. If have a branch circuit rated at 20 amps, it will have more headroom. Anything greater than that will require a special plug. You could also run the unit from a 240VAC branch circuit (though you'd probably have to have this specially wired), in which case the above amperage requirements would be reduced by half. If your studio is in your basement and the power panel is nearby, having an electrician install a special circuit might not be that challenging. In that case, the hard-wired model might indeed be preferable. But I suspect you can just plug it into the wall, and make sure not to plug other power consumers into that same branch.
Rick "thinking it would just be easier to plug the lights into the wall and not worry about minor voltage fluctuations unless it becomes a noticeable problem" Denney
Ginette,
What are you photographing with this setup? It's gotta be possible to get decent light from this type of things, as expensive professional units are available.
The output of regular fluorescent bulbs varies with the temperature of the bulbs. They start off fairly dim, get brighter when they warm up, and then get a little dimmer again when they get too warm. That's why when they're used in enlarger heads it's best to run them with a timer that has a light-output sensor, one that varies the time according to the light output. If the compact bulbs are the same, I doubt that using a voltage stabilizer will help much.
"There are no rules here - we're trying to accomplish something." - Thomas A. Edison
www.peterdesmidt.com/blog
I will try to explain a little more even if English is not my native language, please excuse the non-sense sentences!
I work on location for more than 2 months for photography a collection of sacred vases and other silver objects (like a bunch of spoons). It was taking full size objects pictures and also all the marks on it (vey tiny, some are not visible to the eye).
As silver and gold are highly reflective, I made my own diffusion tent and consider that my set-up didn't vary and that I should obtain consistent color output in my digital images.
So it is why I suspect that color variation (magenta-green axis) may be caused by voltage variation.
I choose theses compact bulbs because they didn't emit heat like tugsten and this can be dangerous for fire so close from my diffusion material ( ripstop nylon) and also for my own confort as I work very close to the lamps. Flashes will not be a good choice because I have really to see the exact light on the objets, really tricky to photography silver objects.
Lamps are open all days long or sometime closed for the lunch. I always let them open for at least 15 minutes before starting to take pictures.
Rdenney, you told about their "MCR Portable Series" ? Is this will be appropriate for lamps, they didn't talk about in theirs applications.
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