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ADE9000 Energy Reading + Conversion Constants

Question asked by avnrdf on Jun 14, 2018

I'm using the ADE9000 Evaluation board with a ADuCM4050 connected over SPI. I also have the SDP & the ADE9000 Evaluation Software.


1. I'd like to confirm the correct method of reading energy:

I'm using the 'read energy with reset' method on page 21 of UG-1098 (ADE9000 Technical Reference Manual).

The microcontroller reads the xHR_HI register, multiplies the register value with the conversion constant and adds it to a 'sum' variable which keeps track of energy over time.

Something like: energy_sum = energy_sum +( SPI_read(xHR_HI) * xHR_HI_conversion_constant );

energy_sum will be the total energy accumulated over the measurement period, with unit Wh.

Do I need to keep track of time (between measurements & total time) in the microcontroller program, or is that handled by the ADE9000 internally?


2. Energy Conversion Constant formula:

The screenshot is from page 52 of UG-1098. The calculation seems to be missing fDSP in the denominator, because if a value is calculated using the given formula, it comes out to 8213.98 (instead of 1.0268 as shown). Dividing 8213.98 by 8000 gives 1.0268.

The formula for conversion constants in the excel sheet (ADE9000_Calibration_Tool_Rev0.xlsm) is:

=(B9*B10*B12)/(B25*B26*'Constants and config'!B11*'Constants and config'!B15*B12*2^-13*3600)*10^6

This formula is similar to the conversion constant in UG-1098, but it includes fDSP in the denominator (*'Constants and config'!B15).

However, the value of accumulation time (B12) is present in the numerator and denominator, which results in them cancelling out and having no effect on the equation.


Could someone please clarify which conversion constant formula needs to be used?