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ADE9000 THD Measurement not working

Question asked by ail@51 on Feb 3, 2018
Latest reply on Feb 18, 2018 by ail@51

Hi!

I'm working with ADE9000 evaluation board EVAL_ADE9000 and the EVAL-SDP-CB1Z system. Using the boards with the ADE9000 evaluation software, I'm trying to measure the THD of a current channel.

If I configure everything, and calibrate the ADE9000, I can read the RMS values of channels ok.

The problem is when I try to read the AITHD register. It is always 0.

The strange thing is that if I read the AIRMS and AIFRMS registers and calculate the THD as is stated in the reference manual, the result I obtain is correct but the THD register is still 0.

As an example:

If I measure the current of an incandescent lamp, the AIRMS and AIFRMS registers are:

AIRMS: 27022915

AIFRMS: 26923138

 

The manually calculated AITHD results 0.086 but the AITHD register is 0.

 

If I measure a Compact Fluorescent Light current, the AIRMS and AIFRMS registers are:

AIRMS: 18455847

AIFRMS: 12983405

The manually calculated AITHD results 1.01 but the AITHD register is 0.

 

If I configure and read the registers with my embedded application via SPI I obtain the same results.

 

What can be happening?

 

Thanks for all and sorry for my poor english!

 

Alberto

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