Wiser Power Meter limitations

Discussion in 'C-Bus Wiser 1 Controller' started by Newbie, Feb 27, 2012.

  1. Newbie

    Newbie

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    Hi Guys,

    I know that the C-Bus power meter is rated at 80amps, what if I wanted to measure a 250amp load with this power meter?

    I would like to measure the load and log it using wiser so that my client can pull up his energy usage on any PC on his LAN

    How would my client print this log using the wiser GUI?
     
    Newbie, Feb 27, 2012
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  2. Newbie

    Don

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    Current measurement range of the C-Bus current measurement unit is not limited to 80 Amperes if you connect an external current transformer. The current measurement unit was designed so that any industry standard current transformer with a 5A secondary can be used. The C-Bus current measurement unit can accept a 5A full-scale range through the use of multiple turns through the unit's clamp-on CT. The current measurement unit can be wired to the secondary of an external current transformer.
    There are sufficient options in Toolkit to allow the unit to be configured so that the reported current takes into account the additional current transformer. The limit I think is around 4000 Amperes full-scale with an external transformer.
    Keep in mind that for the Wiser to display accurate power based on measurements made by the C-Bus current transformer, the power factor of the load must be taken into account.
     
    Don, Feb 27, 2012
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  3. Newbie

    Newbie

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    Great stuff, I thought that you could only use the clipsal CT's

    I will be sure to use a third party CT with a 5amp secondary

    How would I go about changing the range in toolkit to accommodate a 150amp supply?

    I understand that metering the power factor is important when measuring current, how would I do this using C-Bus equipment?
     
    Newbie, Feb 28, 2012
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  4. Newbie

    Don

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    1) Just to make it clear; if you use an additional current transformer, you still need to use the Clipsal CT. The Clipsal CT is required to reduce the 5A range from the external Current transformer to a level that the current measurement unit can accept. Using Toolkit, you need to select 8 turns to get 5A full range ( and you need to actually wind 8 turns through the Clipsal CT).
    2) Good question. It looks like you can't use Toolkit to configure scaled values. At least I can't find it in V1.11.10 (It might still be there somewhere). The unit will still work, but it will report 5A when you feed 5A rms into the Clipsal CT (with 8 turns). You might be able to apply the scaling factor (the additional current transformer turns ratio) somewhere else along the processing chain or perhaps in the Wiser. I'm not sure why this capability is not in Toolkit.
    3) There is no C-Bus unit which can measure power factor directly. For your application, if you need accurate power measurements for loads of varying power factor, you might consider a pulse-type power meter. Some of these can be interfaced to C-Bus with a bus-coupler. There should be a few entries in the forums on this (search).
     
    Don, Feb 28, 2012
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  5. Newbie

    Newbie

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    Thanks Don, appreciate all the advice!
     
    Newbie, Feb 28, 2012
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