AnsweredAssumed Answered

Gain and VRMS Calibration with ADE7758

Question asked by kriscpm on Nov 21, 2013
Latest reply on Feb 10, 2014 by dlath

Good day to all.

 

I am using ADE7758 for my energy metering for my final year project. I have some doubts from the datasheet and I hope I can clear my doubts here.

 

1.I am having some problems calibrating the VRMS whereby the values I got is always approximately the maximum value (50Hz = 166xxxx) althought I've tried varying the input voltages from 0-240V. The changes is not very significant compared to the input voltage. I am using the default gain while calibrating the VRMS.

 

2. With the output results I've obtained, I tried calculating the VRMSOS given in the datasheet, with Vnom = 240V and Vmin=500V, the VRMSOS i got was -262130d. This results is very much larger compared to the example in the datasheet.

 

3. I am not sure what it means by "One LSB of the voltage rms offset is equivalent to 64 LSBs of the voltage rms register." How does this affect my VRMS calibration?

 

4. Does attenuation network of the opamp has anything to do with calibration? If yes, please advise me on how it works.

 

 

Thanks a lot.

 

Regards,

Kristin

Outcomes