I'd like my accumulation registers to reflect real world energy values, with a 1 Wh/LSB constant. Making use of equation 26 on page 50 of the ADE7878 datasheet I get a very high number that makes the registers to be zero all the time.
WTHR = PMAX × fs × 3600 × 10^n / (Vfs × Ifs)
PMAX = 33516139
fs = 8000
n = 0
Vfs = 447.6 (1 Vpp ADC input)
Ifs = 3.54 (1 Vpp ADC input)
The result is 0x08DD69585ED, which makes WTHR0 = 0x009585ED and WTHR1 = 0x00008DD6. If I use those numbers xWATTHR will be zero even after tens of seconds (default read-with-reset enabled), when I apply inputs that generate hundreds of watts in the xWATT registers.
However, if I change the xWTHR registers for new values WTHR0 = 0x00000000 and WTHR1 = 0x00000003 I can see some non-zero values in the xWATTHR registers.
What I am making wrong in the calculation?