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EVM430-F6779 Capabilities Question- Minimum Voltage

Kyle Mann
Intellectual 420 points
Other Parts Discussed in Thread: MSP430F6779

Hello, I am developing a power lab and I want to perform a short circuit test on a transformer. How far below 120V can the meter measure? Also, can you take measurements for a single phase device using only one phase on the board at a time?

Thank You 

  • 0
    TI__Guru**** 216657 points
    Hello Kyle,

    I am bringing this thread to the attention of a Metering expert who will be able to answer your questions.

    Regards,
    Ryan
  • 0 in reply to Ryan Brown1
    Intellectual 420 points
    Thank you for your help Mr. Brown. I need to make a purchasing decision for my employer ASAP.
  • 0
    TI__Intellectual 2595 points

    You can use the phases one by one. This is a requirement for a 3 phase 4 wire utility meter. It has to function with any one or two phases down.

    The MSP430F6779 chip can measure quite small voltages accurately, when its input is scaled to read up to >240V RMS. The EVM compromises this a little, because there is some non-linear voltage drop across the input protection components. How small a voltage are you trying to measure, and what precision do you need?

  • 0 in reply to Steve Underwood
    Intellectual 420 points

    Ideally zero, but at a minimum somewhere in the neighborhood of 20V. Also is there a minimum current? Our lowest current will probably be 20mA.

  • 0 in reply to Kyle Mann
    Intellectual 810 points

    Hi Kyle,

    I have been using the EVM for months putting it through a number of tests including a wide range of voltages.

    I have found the EVM is really quite accurate, this is compared to other meters and scopes etc. I have had voltages as low as 0V and as high as 245V and had made multiple measurements in the region of 3V to 30V and all seems well.

    I have also found the current measurement 'I_rms' was accurate at low levels. This is because it uses Sigma Delta 24 bit ADCs.

    Hope this helps.

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