MI 2792 PowerQ4 Plus
Theory and internal operation
103
For RECORDING with aggregation time Interval:
<
10 sec and on-line measurements,
frequency reading is obtained from 10 cycles, in order to decrease instrument response
time. The frequency is ratio of 10 cycles, divided by the duration of the integer cycles.
Frequency measurement is
performed
on chosen Synchronization channel, in
CONNECTION SETUP menu.
5.1.5 Phase power measurements
Standard compliance:
IEEE STD 1459-2000 (Section 3.2.2.1; 3.2.2.2)
IEC
61557-12
(Annex
A)
All active power measurements represent RMS values of the 1024 samples of
instantaneous power over a 10-cycle time interval. Each 10-cycle interval is contiguous
and non-overlapping.
Phase active power:
1024
1
1024
1
1024
1
1024
1
j
j
p
j
p
j
j
p
p
I
U
p
P
[W],
p: 1,2,3
(7)
Apparent and reactive power, power factor and displacement power factor (Cos
φ
) are
calculated according to the following equations:
Phase apparent power:
p
p
p
I
U
S
[VA],
p: 1,2,3
(8)
Phase reactive power:
2
2
)
(
p
p
p
p
P
S
Q
Sign
Q
[VAr],
p: 1,2,3
(9)
Sign of reactive power:
0
0
0
0
180
0
,
1
180
0
,
1
)
(
p
p
p
Q
Sign
p: 1,2,3
(10)
Phase power factor:
p
p
p
S
P
PF
,
p: 1,2,3
(11)
Cos
φ
(DPF):
p
p
p
i
Cos
u
Cos
Cos
,
p: 1,2,3
(12)
5.1.6 Total power measurements
Standard compliance:
IEEE STD 1459-2000 (Section 3.2.2.2; 3.2.2.6)
IEC
61557-12
(Annex
A)
Total active, reactive and apparent power and total power factor are calculated
according to the following equation:
Total active power:
3
2
1
P
P
P
Pt
[W],
(13)
Total reactive power (vector):
3
2
1
Q
Q
Q
Qt
[VAr],
(14)
Total apparent power (vector):
2
2
Qt
Pt
St
[VA],
(15)
