78M6610+LMU Data Sheet
Reactive Power (Q)
Instantaneous reactive power results (PQA, PQB) are calculated by multiplying the instantaneous
samples of current and the instantaneous quadrature voltage. The sum of these results are then
averaged over N samples (accumulation time) to compute the average reactive power (VAR_A, VAR_B),
and the aggregate average reactive power (VAR_C). A reactive power offset (Qx_OFFS) is also provided
for each channel.
IA
N-1
VA
VQA
PQA_SUM
Quadrature
Delay
If |x|< |y|
z = 0
X
x
z
VAR_A
VAR_C
PQA
PQB
N
N
∑
n=0
y
+
Q_OFFS
IB
N-1
VB
VQB
PQB_SUM
Quadrature
Delay
If |x|< |y|
z = 0
x
z
X
∑
VAR_B
n=0
y
Q_OFFS
Figure 22. Reactive Power Computation
Apparent Power (S)
The apparent power, also referred as Volt-Amps, is the product of low-rate RMS voltage and current
results. Offsets applied to RMS current will affect apparent power results.
IA_RMS
VA_A
VA_C
X
VA_RMS
+
IB_RMS
VA_B
X
VB_RMS
Figure 23. Apparent Power Computation
Power Factor (PF)
The power factor registers capture the ratio of active power to apparent power for the most recent
accumulation interval. The sign of power factor is determined by the sign of active power.
WATT_x
PFx =
VA_x
32
Rev 0
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
