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ADE7878 incorrect calibration?

Question asked by quaterback on Oct 20, 2014

Hi.

 

I use ade7878 to measure electricity.

 

Conditions are as follows:

fLine = 50 Hz

Vn = 230V

In = 5A

Vfs = 389,9693898V

Ifs = 17,677670

VLEVEL = 833381

 

calculated gains (REGS):

VGAIN = -311323

IGAIN = -8022457

So, IRMS and VRMS contain the correct data

 

Next calculated power gain (WGAIN,VA,VAR,FVAR):

Vn = 230, In = 5A, CFDEN = 156, MC = 6400

THR = 140244671 (AN-1076 page 6 (2))

 

Next:

LCYCMODE = 0x27 (C phase using), LINECYC = 200 (1phase = 2 sec), PERIOD = 5120 (use fot WHref calc).

Next connect the load and read RMS, WATTHR, WATT:

VRMS = 2297451, IRMS = 2818. Whref = 35,96787177 * 10^-3(Wh). WATTHRref = 36. But WATTHR reg contains 1 or 2 and WATT reg contains 747.

 

I reduced the THR register 20 times and WATTHR reg value is changed to 27 (WATT is unchanged)

 

I calculated  WGAIN reg based on the new WATTHR reg.

So WGAIN = 2326840.

 

Now WATTHR reg looks right, but WATT reg contains 960 (value appears reduced by 20 times the correct: (229.7451 * 0.2818)/(17.677670 * 389.9693898)*(33516139/16) = 19672)

What did I do wrong?

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