hello,

I am working with the ADE7878 for a 3-phase industrial application,i need to measure voltage,current,active power,apparent power,active energy,power factor,harmonic.my coefficient of resistor divider is 1411,CT is 3000:1 ,and current sample resistor is 4.7ohm,input power is 50w,voltage is 220v,so current is 0.227.

all configure without gain,and i can have calculated vrms and irms are 216V(input voltage maybe a little less than 220v) and 0.243A ,but ,when i read the power from xWATT registers are d'980'~d"1010",it seems 50w should multiplied 20 ,it is same as xVA registers,i am confused ,how can i get correct value?

how could i use this formula?Ufs = 0.5/1.414 ?;Ifs = 0.5/1.414 ??; Uk = 216/1141 ? ;Ik = 0.227? but no matter how,i still can not get the value of d"980"~d"1010"

Hi Rex liao

Uk and Ik are the RMS values of test voltage and test current input provided

Ufs and Ifs are the RMS values of voltage and current input that need to provided so that the signal level entering the pins of ADE7878 is at full-scale (0.5/1.414 V)

Based on your inputs:

Uk= 216V

Ik= 0.243A

Ufs= (0.5/1.414)*1411=498.93V

Ifs= (0.5/1.414)/4.7*3000=225.67A

So, estimated WATT register value will be : 216*0.243/(498.93*225.67)*33516139/(2^4) ~=977 (This is theoritical, based on real PMAX value, this number might be slightly different)

Anyways, this is more in line with what you are getting. Does this clarify your doubts?

Regards

hmani