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125v vs 250v Movers...+ advice?

Discussion in 'Lighting and Electrics' started by Jezza, Nov 30, 2006.

  1. Jezza

    Jezza Active Member

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    Hey all, just a few quick questions if anyone has the time:

    I'm looking into renting a few movers for a pretty big concert at my school in February and just need some clarification. Having worked with VL2500s before and loved them, I would like to rent them again. When I have rigged them up previously, I have only fed them 125v through a 125v to 250v twist-n-lock connector. Does diminishing the voltage also diminish output or does the fixture automatically "know" and require more amps to operate at a lower voltage? The reason why I ask is that power is limited and I would like to tap as many instruments into the same 20A line as possible.

    Additionally, I do not have the capability nor the resources to rent a moving light distro and tie it in seperately from my Sensor 96. However, using an Express 48/96, is it "kosher" to inhibit certain dimmers to be at "full level at 1%", "park" them and use the power comming from those dimmers to power up some movers? To me, it doesn't sound like a technical issue but I'm no expert, that's why I'm asking!

    Thanks for the help guys, any questions, just ask!

    -Jer
     
  2. zac850

    zac850 Well-Known Member

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    1: Some movers have auto-sensing power supplies. That is, you feed them any voltage (usually from 100 to 240 volts) and they will run happily. If you are only going to be feeding the movers 120 volts, then make sure the movers are happy running on 120 volts (when you go to rent them, make sure that they have either an auto-sensing power supply or they are 120 volt movers).

    Using 120 volt fixtures as opposed to 220 volt fixtures does not have any noticeable impact (well, not largely at least, this has been debated off and on before).

    2: No.
    Either invest in some sensor relay modules or plug them directly into the wall (depending on power load of course). The movers will not be happy running off an SCR dimmer.
     
  3. Jezza

    Jezza Active Member

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    Zac-

    Thanks for responding. Good to know, on all of that. However, can you explain, possibly in more detail as to why the movers wouldn't be happy running off an SCR dimmer or how the SCR dimmer functions differently from a noramall wall outlet at 100%. I would imagine that it would be even more stable than a wall outlet as it is precision regulated and is the rack is used to handling large power draws instantaneously.

    Thanks
     
  4. SteveB

    SteveB Well-Known Member

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    >I'm looking into renting a few movers for a pretty big concert at my school in February and just need some clarification. Having worked with VL2500s before and loved them, I would like to rent them again. When I have rigged them up previously, I have only fed them 125v through a 125v to 250v twist-n-lock connector. The reason why I ask is that power is limited and I would like to tap as many instruments into the same 20A line as possible.<
    Yes, you can run it at 120v without loss of output. You'd best check what the VL 2500 power draw is at 120v (120 is more normal then 125. Are you sure your single phase power is at 125 volts ?). I'd doubt you can get 2 units on a 20 amp feed at 120v.
    >Does diminishing the voltage also diminish output or does the fixture automatically "know" and require more amps to operate at a lower voltage?<
    Exactly. The power supply adjusts to line voltage.
    >Additionally, I do not have the capability nor the resources to rent a moving light distro and tie it in separately from my Sensor 96. However, using an Express 48/96, is it "kosher" to inhibit certain dimmers to be at "full level at 1%", "park" them and use the power coming from those dimmers to power up some movers?<
    You should absolutely NOT power any ML or any device that has an electronic power supply off a dimmer parked/whatever at full (it's not good for a magnetic ballast either). The dimmer still has a partially chopped sine wave and you run the risk of frying the ML electronics. There has been much written on the professional sites - LightNetwork as example, about why not to do this.
    When renting the fixture (assumption), see if you can get your hands on either Sensor R20 relays or a Constant Circuit Module. The relays are similar to a dimmer, just has 2 - 15a or 20a relays built in to respond open/closed to a DMX signal. OR, the Sensor Constant Circuit Module that just has a pair of circuit breakers with no DMX control, simply on/off via the CB.
    SB
     
  5. Jezza

    Jezza Active Member

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    Gotcha, thanks. I am continually trying to find a course, book, seminar, etc. that will explain more about electrical theory as it pertains to the entertainment industry. Just when i think I understand something, I realise I am wrong, as you have just shown. Any ideas where I can aqcuire a more in-depth knowledge of these topics aside from a college level physics course that won't focus on electricity?
     
  6. zac850

    zac850 Well-Known Member

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    I don't know as much as I wish I did, but as Steve said, you can't power movers from a dimmer because of the harmonic distortion of that dimmer.

    A dimmer works by turning the power supply on and off 120 times a second, and even at 100% this still happens a bit. Movers don't like this.

    As for learning more, I'd start at the wikipedia article (http://en.wikipedia.org/wiki/Electricity) and run links off that. You can also get some good info from wikipedias article on dimmers (http://en.wikipedia.org/wiki/Dimmer)
     
  7. len

    len Well-Known Member

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    As was mentioned, some lights are auto voltage sensing. The only one I've used is the HES StudioCommand 700 watt. It's a nice feature to have. Most others I've used can be adjusted manually, but it typically requires removing some covers and throwing the switches. Not a big deal but if you have to change 50 of them every week ...

    I saw a bunch of HES Color Pros get tried on the wrong voltage once. A fuse popped (as it should have) and the 80 feet of fiber optic curtain they were supposed to illuminate was useless because they couldn't find the correct fuses.

    One person I know in cyberworld says he runs lights off dimmers all the time. I never have and hope I'll never have to. On the surface it SOUNDS like it would work. BUT I wouldn't try it.

    And no, I've never noticed any difference when running 110/208. I think the Martin Atomic strobe has decreased output when run on 110 but I could be wrong.
     
  8. soundlight

    soundlight Well-Known Member

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    We run dimmers in switched mode whenever we have to power movers from them. We have 380 sensor advanced feature modules, and we just go down, open up one of the racks, and punch a few buttons. Bam. Switched mode. That way, it sends straight power to the circuit (this is what I understand).
     
    Last edited: Dec 1, 2006
  9. SteveB

    SteveB Well-Known Member

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    Here's a cut and paste from a VariLite technical bulletin: I got this on a Google search, BTW.

    It is not recommended to power any VARI❋LITE® products from a dimmer -even in 'NONDIM' mode. A dimmer is not a suitable source of power because its output modifies the AC wave form. This may work for a while, but could eventually result in power problems. This is especially critical in the case of VL1000 on-board dimmer models (VL1000TS/VL1000TID/VL1000TSD), since this would essentially be powering a dimmer from a dimmer.This does not work because all dimmers require a clean, complete wave form in order to operate correctly.

    ETC SOLUTIONSIt is not recommended to power any VARI❋LITE products from an Electronic Theatre ControlsD20 or D20E dimmer module. Once again, this is especially critical when using the VL1000 on-board dimmer models.As an alternative, you can still distribute power from your existing rack by substituting either an ETC CC20 constant circuit module or ETC R20AF relay module. These are constant current breakered modules available in both 120V and 230V versions

    There have been trade journal articles that describe this in better detail. If I get time, I'll see if I can dig this up.

    Bottom line is this statement from the manufacturer would indicate you would void any warrenty by powering ML equipment in this manner.

    SB
     
  10. soundlight

    soundlight Well-Known Member

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    We only run our HES Intellabeams (which are 5+ years old) from the dimmers, we run the Vari*Lites that we rent out of the distro. And we run them 208V. Well, don't run Vari*Lites from dimmers!
     
  11. SteveB

    SteveB Well-Known Member

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    Note that the Advanced Feature Sensor dimmers only means the dimmer can talk back to the console via Link. AF has no affect on output. Even fast rise rate dimmers have the same issues in ND mode.
    The reason using dimmers in ND mode is not recommended is that all Switched/ND Mode does is sets the dimmer to full output when the incoming data is at a certain threshold. This is usually a configurable point such as 95% of value, 5%, 98% etc...
    The dimmer is still a dimmer and chops the sine wave. In addition, God help you if someone does something stupid at the controller and the dimmer dims.
    This subject is similar to the topic of using microphone cable as 3 pin DMX cable.
    Yes it works, most of the time, but may not when you least expect it. The trouble with dimmers in ND mode is the result when it doesn't work, is a toasted fixture power supply and mother board(s). Or multiple fixtures. Paying for the repairs costs more then getting breaker modules or relay modules.
    Enough said
    SB
     
  12. Van

    Van CBMod CB Mods Premium Member

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    I couldn't agree with SteveB anymore ! I would not even use an IPS dimmer with moving fixtures, and they are truly designed to sense inductive loads automaticly. I hate not having a great answer to your power issues, my first thought was "T" off your sensor rack twistlocks put in a 10/5 panel and watch you load. Then I read the part about a distro not beingan option. Perhaps using moving lights is not an option. ? This is something I run up against all the time. Directors / Producers / Designers, want the moon and all the bells and whistles, I want to give it to them,But the book keeper is the real power.
     
  13. TechiGoz

    TechiGoz Active Member

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    As far as I know, its alright to run ML's through Patch points, but then through a GPO or Distro from 3-phase etc. Then again, that could be totally off topic from what you are talking about.. So sorry if it is! :S :)
     
  14. Chris15

    Chris15 CBMod CB Mods Premium Member

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    I agree. The problem does not come from using any of the cabling infrastructure, it comes when you put the power through the dimmer module and start altering the "pure" sine wave that comes in. Though it would come as no surprise to find imperfections in the mains waveform.
     

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