Hi,We are trying to calibrate and obtain Wh/LSB and VAh/LSB constant for the ADE7763.We used the LINECYC Mode in order to simplify the job. A reference meter is used to compare with the values obtained from the ADE.After trying with several amount of time accumulation we came up with a more or less stable constant for Active Energy around 4.53 x10^-5. The same process was followed for Apparent Energy.All measurements were done with a Power Factor of 1, and for different Load conditions.The problem is that in normal operation when we apply the constant in order to obtain the Active Power or the Apparent Power there is an error of 20 to 25%.There is any reason for this behavior?After that, the procedure was to calibrate in Power at a glance, I mean with a constant Load measure the Power with the reference meter and adjust the constant previously obtained to fit the correct value. This works pretty much accurate when we try with different loads.
Maybe is something we are missing?Thank you very much
Hi. Any ideas on what could be wrong? The errors we are obtaining are very large.
Hi Solar and sorry for the late reply
When using line cycle accumulation mode, the accumulation time is function of the period register so i would suggest you to initialy check that this value is stable and accurate. Of course, the bigger is the LINECYC register values, the less noise you are going to observe on the active energy.
What do you mean by "different Load Conditions"? Calibration parameters are linked to the load. It would be helpful if you could describe more in the detail your calibration procedure
During normal operation mode, do environment conditions (like temperature) change?
HI Valeria. Thank you for your reply and sorry for our late re-reply. We had abandoned the project for a couple of months. We are back on track now and still having problems with calibration.
One example is:
- We have five AC meters we built for testing and starting trying to calibrate Vrms and Irms.
- We input the normal grid to the meter and a constant load. We measure V and I with a precision multimeter (fluke 177)
- We calibrate the first meter as said on the datasheet and obtain the calibration constants and use these for all meters.
- We do not do offset or phase calibration.
- We are using shunt resistors for measuring current.
The first meter measures correctly V and I in different ranges. The rest of the meters DO NOT measure the same V or I and there are differences of up to 10% between some of them. As we have read, for the same circuit the calibration should be the same and results should be below 1% accuracy.
What could be the problem? PCB layout? component selection? Wrong calibration procedure?