ADE7880
Data Sheet
Table 16 presents the settling time for the fundamental reactive
power measurement, which is the time it takes the power to
reflect the value at the input of the ADE7880.
Table 16. Settling Time for Fundamental Reactive Power
Input Signals
63% PMAX
100% PMAX
375 ms
875 ms
Fundamental Reactive Power Gain Calibration
The average fundamental reactive power from the LPF output in
each phase can be scaled by ±100% by writing to one of the phase’s
VAR gain 24-bit register (APGAIN, BPGAIN, or CPGAIN). Note
that these registers are the same gain registers used to
compensate the other powers computed by the ADE7880. See
the Active Power Gain Calibration section for details on these
registers.
Fundamental Reactive Power Offset Calibration
The ADE7880 provides a fundamental reactive power offset
register on each phase. The AFVAROS, BFVAROS, and CFVAROS
registers compensate the offsets in the fundamental reactive
power calculations. These are signed twos complement, 24-bit
registers that are used to remove offsets in the fundamental
reactive power calculations. An offset can exist in the power
calculation due to crosstalk between channels on the PCB or in
the chip itself. The resolution of the registers is the same as for
the active power offset registers (see the Active Power Offset
Calibration section).
As stated in the Current Waveform Gain Registers section, the
serial ports of the ADE7880 work on 32-, 16-, or 8-bit words
and the DSP works on 28 bits. Similar to the registers presented
in Figure 43, the AFVAROS, BFVAROS, and CFVAROS 24-bit
signed registers are accessed as 32-bit registers with the four
MSBs padded with 0s and sign extended to 28 bits.
HPFEN BIT
DIGITAL
AIGAIN CONFIG3[0] INTEGRATOR
IA
APHCAL
HPF
HPFEN BIT
AVGAIN CONFIG3[0]
VA
HPF
FUNDAMENTAL
REACTIVE
POWER
ALGORITHM
APGAIN AFVAROS
:
DIGITAL SIGNAL PROCESSOR
24
AFVAR
INTERNAL
ACCUMULATOR
THRESHOLD
REVFRPA BIT IN
STATUS0[31:0]
AFVARHR[31:0]
32-BIT REGISTER
34
27 26
0
VARTHR
0
Figure 77. Fundamental Reactive Energy Accumulation
Rev. A | Page 50 of 104