ADE7754 Ver la hoja de datos (PDF) - Analog Devices
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ADE7754 Datasheet PDF : 44 Pages
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IA
PHASE A
VA
AAPGAIN
0
IB*
HPF
–
+
1
AAPOS
+
28
AWGAIN
LPF2
IB
PHASE B
VB
BAPGAIN
IC
PHASE C
VC
CAPGAIN
HPF
IB*
BAPOS
+
28
LPF2
1
BWGAIN
0
IB*
HPF
–
+
CAPOS
+
28
LPF2
1
CWGAIN
Figure 26. Total Active Power Consumption Calculation
ADE7754
TOTAL INSTANTANEOUS
POWER SIGNAL
ACTIVE POWER
SIGNAL – P
2752545h
For example, for WATMOD = 1, when all the gains and offsets
corrections are taken into consideration, the formula that is
used to process the active power is
Total Active Power =
VA
×
1
+
AAPGAIN
212
× IA
−
1
+
BAPGAIN
212
× IB
+
AAPOS
× 1 +
AWG
212
+VC
×
1
+
CAPGAIN
212
×
IC
− 1 +
BAPGAIN
212
×
IB
+ CAPOS
× 1 +
CWG
212
Depending on the polyphase meter service, an appropriate for-
mula should be chosen to calculate the active power. The
American ANSI C12.10 standard defines the different configu-
rations of the meter. Table II describes which mode should be
chosen for each configuration.
ANSI
5S/13S
6S/14S
8S/15S
9S/16S
Table II. Meter Form Configuration
Meter Form
3-wire Delta
4-wire Wye
4-wire Delta
4-wire Wye
WATMOD
0
1
2
0
WATSEL
3 or 5 or 6
5
5
7
Different gain calibration parameters are offered in the ADE7754
to cover the calibration of the meter in different configurations.
Note that in Mode 0, the APGAIN and WGAIN registers have
the same effect on the end result. In this case, APGAIN regis-
ters should be set at their default value and the gain adjustment
should be made with the WGAIN registers.
ENERGY CALCULATION
As stated earlier, power is defined as the rate of energy flow.
This relationship can be expressed mathematically as
P = dE
dt
(7)
where P = power and E = energy.
Conversely energy is given as the integral of power.
E = ∫ Pdt
(8)
The ADE7754 achieves the integration of the active power
signal by continuously accumulating the active power signal in
an internal non readable 54-bit energy register. The active
energy register (AENERGY[23:0]) represents the upper 24 bits
of this internal register. This discrete time accumulation or
summation is equivalent to integration in continuous time.
Equation 9 expresses the relationship
Σ E = ∫ p(t)dt = Lim ∞
p(nT
)
×
T
T→0 n=0
(9)
where n is the discrete time sample number and T is the
sample period.
REV. 0
–19–
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