I would like to know how to realize 16 bit power factor register values into actual PF values. (ADE-7953)
The PF registers are 16-bit 2's complement registers. So just get the decimal equivalents of the registers, comprehending the sign from the sign bit. The exact value can be found by multiplying it by 2^(-15).
So if you read 0x4000 in the register, that corresponds to PF of 0.5; a measurement of 0xC000 would mean PF of -0.5.
The register value i obtained are FFB7, FFB8, FF00 when i convert them to decimal and multiply by 2^-15, I get values greater than one. Can you please clarify.
Also, Please let me know how to convert the real, apparent and reactive power register. Currently i am reading these values from the registers
Active power - FF FA 92 6B
Reactive power -FF F7 05 86
Apparent power- 00 0A 82 F9
use case : refrigerator
The registers are signed registers. So you will have to take the 2's complement ( for negative number- sign bit 1) of the binary equivalent and then comprehend it in decimals.
For example, FFB7 is 1111 1111 1011 0111 in binary. Its 2's complement is 1001001, which corresponds to 73. So the number is actually -73. Now multiply by 2^-15 to get PF.
That is why I had shown two examples( PF 0.5 and -0.5) in my earlier reply.
For powers also, the conversion is similar except that you need not multiply it with 2^-15. What decimal equivalent you get, will be in LSBs. You will find a constant (like KWh/LSB for active power) during calibration, which can be used for conversion to real- world values.
Hi Hmani ,
Thanks for the reply .
I had followed the above method prior as well , but since this did not result in a practical answer, i sought your help .
As per your instruction - 73*2^-15 is equal to " 0.0022 ".
For a refrigerator load this seems very unlikely .
Please let me know , where i am going wrong .
Did you compare the energy register readings at that power factor, to compare and see if it made sense?
I don't see any correlation between the Power factor derived from energy registers and power factor register .
The following are the register readings .
Note : Vrms = 229 , IRMS=1.6A
BWATT - FFFA19ED
BVAR - FFF69F6A
BVA - 000B16E5
PF - FFBB
ANGLE_B - FFFA
The above values are the actual values of the register .
I am confident of Vrms , Irms and apparent power values but not others .
Please clarify the same
Yes. The results do not correlate at all. Can you let me know the amplitude and phase of the voltage and current signals entering the part?
If the current and voltage are in phase now, introduce a phase shift of 45 degree between them and read these register values again.
Also, it is good to check if you get the same results when connecting an ideal source at the input. I have seen such kind of erroneous results due to the switching ON and OFF of loads, if the setup is improper.
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