Energy Meter energy calculation from power

[bobdxcool]

I have interfaced a smart energy meter IC (ADE7878) to a microcontroller. The datasheet of the IC can be found here,

http://www.analog.com/media/en/techn..._7868_7878.pdf.

As per the datasheet, on page 50 total active power of each phase can be read from the registers AWATTHR, BWATTHR, and CWATTHR. My question is what parameters I should consider and formula I should use to calculate the kwh value ?

 

[waross]

Try (AWATTHR+BWATTHR+CWATTHR)/1000

Bill
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"Why not the best?"
Jimmy Carter

 

[bobdxcool]

Thanks for your reply. But the values given out of these registers are 32 bit. I was thinking how do I convert it to the actual value. I think there is some conversion factor.

 

[bobdxcool]

As per the datasheet(page 58), PMAX = 33,516,139 = 0x1FF6A6B, the instantaneous power
computed when the ADC inputs are at full scale. So will dividing the value obtained from the register by Pmax give me the actual wh value ?

 

[Skogsgurra]

Sum the hex values for the period you are interested in (probably 1 h) and then divide by the scale factor. If you divide first, you will lose a lot of resolution.

I assume that your computer handles 64 bit unsigned, in that case there is ample room for the summation.

Gunnar Englund

http://www.gke.org

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