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Thread: how much power do projectors use?

  1. #1
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    Default how much power do projectors use? / powering them without a power socket

    EDIT: The way some of the members here have desperately tried to identify my location and nationality for whatever reason they believed was needed for by asking an admin to check my profile logs and researching me by the content of my posts has been very creepy and unnecessary. So bye.
    Last edited by dream; 04-28-2016 at 16:42. Reason: better topic title

  2. #2
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    For solid state the mains consumption is pretty low actually.

    Rough rules of thumb:

    For each SS and DPSS module factor Roughly 3W for every 1W of optical output.
    DT40W scanners around 70W
    DT30 around 50W
    Add in few watts for shutter, color correction board etc.
    Add in a few watts for fans, plus any additional TEC coolers (around 10W per sq inch).
    This is worst case, laser on all the time which they are not, nor are the scanners working hard all the time.

    The total is then divided by 0.8 on average for switch mode PSU efficiency. The other thing to then consider is power factor which may be poor (0.6), so divide by this to derive VA from W. VA is more the figure you want and your UPS may well be rated in VA only not W.

    Given your mains voltage (110 or 230) you can determine amps by dividing VA by mains voltage. Time can then be calculated, but beware UPS ratings vary according to quality, source etc. Leave plenty of headroom is my suggestion.

    Keen to know how it pans out basednon my rules of thumb, we could add this to the WiKi if valuable.

    Its my rough guide so I prepare to be flamed.
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  3. #3
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    I'd not recommend running a projector on UPS alone as I'm pretty sure that it won't be drawing the same current all the time - And to get something close to running a unit (other than a feasibility test) for any useable length of time will require bulky and expensive batteries.

    Have you considered using a surge protected jenny instead?
    In science one tries to tell people, in such a way as to be understood by everyone, something that no one ever knew before. But in poetry, it's the exact opposite - Paul Dirac

  4. #4
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    Are you getting there by car?

    If so, buy or hire a true sinewave 'inverter' that runs off the car battery, making sure it is one that can stand the noisy input from a car's generator. (People with larger boats or mobile homes often have these things). Get a heavy earth wire to bolt to car chassis and connect to the water piping or other major metal structure of the venue. Then you run mains cables as usual from the inverter's socket(s). Leave the car engine idling to keep the battery topped up.

    To find out how much power your projections will want, look at average and peak of current measured on the main power line. Don't try to guess, it's always easier to measure. A good sinewave inverter will likely have a peak power output about twice its constant RMS rating.

    EDIT: Examine all of your laser gear to see what kind of power supply it has. If it is the 'universal' switching type that can take any supply voltage from 80V or less to as much as 265VAC, you can probably use a much cheaper 'modified' sinewave inverter. Those put out a bipolar timed rectangular waveform to crudely emulate the character of a sine wave. They can stress a PSU's filtering components, but in a universal supply those are rated strongly because some countries use low volts, so high current for a given power. In other words, you can usually get away with it. But if you CAN get a true sinewave type, do it. It takes the worry right out of the equation.
    Last edited by The_Doctor; 10-29-2013 at 03:27.

  5. #5
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    Quote Originally Posted by dnar View Post
    For each SS and DPSS module factor Roughly 3W for every 1W of optical output.
    Where did you get this figure, Wayne? An average 1 watt DPSS green pulls at least 6 amps from a 5 volt PSU. That's 30 watts right there, not counting the losses when converting from AC to DC. Did you drop a zero or something?

    In my experience, most projectors don't pull more than 2 or 3 amps from the AC wall plug. So if you wanted to play it safe, you'd select a UPS that could deliver ~300 watts for at least 50% longer than the time you expect to run the show. (IE: 30 min show, need 300 watts for 45 minutes)

    But again, given that the power requirements are so low, why not just run an extension cord? It doesn't have to be heavy gauge wire, because it will only be carrying a couple amps of current. Get 100 feet of cheap lamp cord and you're all set... (Remember, UPS batteries are heavy!)

    Adam

  6. #6
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    Quote Originally Posted by buffo View Post
    Where did you get this figure, Wayne? An average 1 watt DPSS green pulls at least 6 amps from a 5 volt PSU. That's 30 watts right there, not counting the losses when converting from AC to DC. Did you drop a zero or something?

    In my experience, most projectors don't pull more than 2 or 3 amps from the AC wall plug. So if you wanted to play it safe, you'd select a UPS that could deliver ~300 watts for at least 50% longer than the time you expect to run the show. (IE: 30 min show, need 300 watts for 45 minutes)

    But again, given that the power requirements are so low, why not just run an extension cord? It doesn't have to be heavy gauge wire, because it will only be carrying a couple amps of current. Get 100 feet of cheap lamp cord and you're all set... (Remember, UPS batteries are heavy!)

    Adam
    Sorry, brain fart. I did initially spec different figures for SS vs DPSS, then forgot DPSS have at least 1 TEC, typically 2 so there you go. I also screwed up the guestimate of IR power. Thinking 2-3W IR for 1W 532nm, but the power to generate 2-3W or IR is a lot more. I think we should start a spreadsheet style wiki to nail these figures more accurately, then you can "build" your setup in the sheet and calculate power requirements.
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  7. #7
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    W = V x A

    so

    Lets say 140W and your mains is 110V. I will ignore power factor here to keep it simpler.

    Amps = W / V
    Amps = 140 / 110
    Amps = 1.2727
    mA = Amps * 1000
    mA = 1272

    So, it you want to run for 5 hours, multiply 5 x 1272mA = 6360mAh (or to get back to amp hours divide by 1000 = 6.36Ah).

    Typically you deal in amps and amp hours, so it's simply 1.2727A x 5h = 6.36Ah.

    Power factor, actual mains voltage etc. will alter this some what, but for the purpose you require close enough is good enough as you should design to have an order of magnitude (x2, x3 or x4 etc.) up your sleeve to allow for aging batteries, unexpected load increase, bad planning, dodgy estimates, crappy laser colleagues that mislead your calculations with poor DPSS estimates etc. The key is what does the UPS output do when reaching the rated amp hours? I bet it's maximum power and possibly output voltage is reduced.
    Last edited by dnar; 10-29-2013 at 07:34.
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  8. #8
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    Just checking, you did substitute 140W in the example above with your power figure and same for mains AC voltage right? (I was in no way suggesting yours was 140W and 110VAC, just figures plucked from the ethersphere for the purpose of an example).
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  9. #9
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    "Compact" UPS never run as long as indicated on the box IMHO.

    Your going to have to trial this first me thinks. Do let us know!
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  10. #10
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    I would personally use leisure batteries (or preferably marine batteries as they are deep cycle and operate at lower temperatures).

    A lot cheaper than UPS and a lot more uses after the gig.

    Keith

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