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ADE7880 IRMS Calculation

Question asked by Jacques007 on Feb 12, 2018
Latest reply on Mar 8, 2018 by Gary.Kang.AnalogDevices

HI, 

I am working on a project with ADE7880, I have a question about current (and voltage) RMS calculation. In datasheet it is stated that RMS values are updated on 8KHz, or at each 125 us. So the new data is in XIRMS  (for current) register is available after each 125us. So new value represents RMS value of all samples that are acquired during that 125us time interval? I am not quite sure how to interpret values that are obtained from XIRMS registers.

 

For example if I want to sample one period of 50Hz signal, and I want 20 samples, one sample on each 1ms, that means that I have to wait for zero crossing to occur, than read 8 samples on each 125us, average those 8 samples and that is my reading on 1st ms of interval. I need to do same thing 19 more times in  order to sample one period, is that correct?

 

As I figured out there is no mechanism in ADE7880 to do this kind of measurements automatically, somehow to set period and then get RMS value of whole period in one reading, is that correct?

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