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Control/Dimming monitoring power usage

Discussion in 'Lighting and Electrics' started by Beans45601, Jan 22, 2012.

  1. Beans45601

    Beans45601 Member

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    Mostly out of curiosity, I am interested in monitoring the actual power usage of our dimming system (cd-80 rack, 192 dimmers). I was wondering if anyone had ever put together a project to do such a thing? How would you pull off such a project?

    I am thinking something like a modified kill-a-watt meter with a clamp meter for each leg of the power coming in.
  2. JD

    JD Well-Known Member

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    Problem is the waveform is not sinusoidal and unless you get a meter that factors "True RMS" you will get a bad reading.
  3. cpf

    cpf Well-Known Member

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    I'd think the phases going into the dimmer would be sinosoidal?
  4. STEVETERRY

    STEVETERRY Well-Known Member Premium Member

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    The voltage feeding the rack is indeed sinusoidal, but a phase-control dimmer rack is a non-linear load and does not draw current in a sinusoidal waveform. This requires a true-RMS-responding instrument.

    What is needed for the task suggested by the OP is a three-phase Power Quality Analyzer that can create a record of usage over time.

    ST
  5. cpf

    cpf Well-Known Member

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    Riiiight, I thought I was forgetting something...
  6. shiben

    shiben Well-Known Member

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    They make meters to find out how much to charge you, one would suppose you could get another one installed between your rack and the supply to find out... Or one could take a reading at the start of a day off your main meter, not use your system all day and take a reading at the end, do this a few times to get a good average, then do it on days when you do use your system, average those, and compare the difference.
  7. avkid

    avkid Not a New User

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    A meter base and meter is very easy for any electrician to install.
    (heck, we've got a case of them in the warehouse)
    However, asking them to do it may get you labelled as nuts.
  8. epimetheus

    epimetheus Active Member Premium Member

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  9. headcrab

    headcrab Active Member

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    I've heard this company http://www.emon.com/index.html referenced on Mike Holt's forum a few times.
  10. JD

    JD Well-Known Member

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    Not sure how accurate a standard electric company use meter would be. I suspect it would err on the side of "high" on low power factor equipment ;)

    After all, we know how fond they are of things that aren't 1.00 !

    I also suspect you are looking for real-time feedback. I suspect there is something "off the shelf" out there, but must admit I never looked.
  11. Chris15

    Chris15 CBMod CB Mods Premium Member

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    Back when I was building power distros amongst other things, our standard metering arrangement for a main distro was a Schneider PM700 series with approriate CTs.
    PM700

    The manufacturer claims true RMS, accurate to the 15th harmonic...

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