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EMDC Reading the power factor

Colin Forster
Prodigy 50 points

Part Number: MSP430i2020i

Hello,

I've a working project using the MSP430i2021i and EMDC but the power factor value is bouncing around.

It maybe it's very small, but I'm not sure so it might look worse than it is.

How should the value be interpreted, how do I make it a meaningful valve from 0.000-1.000.

Two more questions:-

1) I'm assuming activePowerSF always equal to the reactivePowerSF

2) Is it possible the tune the phaseCorrection, what are the incremental steps and how does this relate to the voltage / current phase as the calibration never works.

Thanks,

Colin

  • 0
    TI__Mastermind 49692 points

    Hello,

    The power factor is basically active power divided by apparent power can be used to determine the phase angle between the voltage and current. Search online for "power factor" to learn more.

    Colin Forster said:
    1) I'm assuming activePowerSF always equal to the reactivePowerSF

    Correct.

    Colin Forster said:
    2) Is it possible the tune the phaseCorrection, what are the incremental steps and how does this relate to the voltage / current phase as the calibration never works.

    Are you saying the calibration doesn't work when using the EMDC GUI? Are you using an accurate test setup to apply a specific phase angle? The phaseCorrection value contains the whole and fractional sample delays. For fractional, this is the preload bits that get adjusted. For whole, this is the index for an array that gets adjusted. If these values are incorrect, it will impact the accuracy of the power factor.

  • 0
    Prodigy 50 points

    Hi James,

    Thanks for the reply, I understand what the power factor is but I don't know what 0x00004000 means, how do I get to a fractional number.

    Is this scaled up, it doesn't say in the software.

    On the calibration, it just doesn't work consistently, I've only connected to the board twice and had results.

    I just gave up on the GUI it's very unreliable.

    It's says connected but I notice that to doesn't read the ID, only when you see the ID in the bottom corner does it work.

    Thanks,

    Colin.

  • 0 in reply to Colin Forster
    TI__Mastermind 49692 points
    Colin Forster said:

    I understand what the power factor is but I don't know what 0x00004000 means, how do I get to a fractional number.

    Is this scaled up, it doesn't say in the software.

    Have you referred to the Protocol section in the EMDC Technology Guide? It's a good reference for these types of questions.

    Colin Forster said:
    On the calibration, it just doesn't work consistently, I've only connected to the board twice and had results.

    I didn't see an answer about an accurate test setup. This is required for accurate calibration. The example projects and binaries are pre-calibrated using our accurate test setup in the lab that allows you to adjust the phase angle between voltage and current.

    Did you follow the calibration instructions in the Calibration section of the EMDC Technology Guide?

    Colin Forster said:

    I just gave up on the GUI it's very unreliable.

    It's says connected but I notice that to doesn't read the ID, only when you see the ID in the bottom corner does it work.

    Interesting. This can happen if your connections are loose, if UART TX/RX are backwards of if the EMDC project is different than what's been programmed on the device.

    Read through the Known Limitations section of the EMDC Technology Guide.

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