Hi Dlath,
I had disable the LINECYC to read the energy register only and the AWATTHR seem to increase constantly. When the load increases, the AWATTHR register reading increases with every readings. I presume this is correctly done.
Hence, I try to enable the LINECYC again to test the AWATTHR. However, when I tested with different LINECYC ( different number of zero-crossing), lets say if I tested with different loads, setting the LINECYC to 0x800 ( 2048 zero crossings), the AWATTHR reg will not change. When I set the LINCECYC to 0x64 (100 zero crossing), the AWATTHR reg will varies according to the different load. What is the depending factors of the LINECYC that affect the AWATTHR reading?
With the LINECYC of 0x64, the accum time will be around 0.33333 seconds as obtained from eqn61. does this mean every 0.33333 (when the LENERGY interrupt occur), the value should be stored into a constant variable to avoid overflow? Fyi, the constant variable is use to store all the accumulated watt hour register readings.
Secondly, when come to xWG register (eqn 63), my calculated values seem to be too large (approximately 102k) which seem to be illogical. As far as I concern, this is because the AWG register maximum length is only 2^12=4096 only. In order to decrease the xWG value, I increase the APCFNUM to 10 (previously was 1 in eqn 60). Eventually, the reading of xWG seem to be more relevant. Is this method correctly done?
After setting the xWG, I had calculated the Wh/LSB and this value is multiply to the AWATTHR to get the real world Watt* hours value. Nevertheless, the value is not tally when compare to a small error percentage energy meter.
---> "When compare to smart meter, 8kwh, 2446 watt, V_nom= 226.6 and I_test= 10.71"
I attempt to calculate the real power of load. One of my doubt is, if I use the method of using the accumulated watthr result divided by the total accum time, will it be the correct real power reading. How about using the reading of AWATTHR register to divide with accum time(0.33333sec) and then convert to real value by multiplying the Wh/LSB constant?
Best regards,
jianyee92