4 Measurands and Characteristics
4.3 Calculation of the Measurands
37
SICAM MMU 7KG9663, Device Manual
E50417-H1040-C514-A3, Edition 01.2016
4.3
Calculation of the Measurands
Table 4-6
Calculation of the Measurands
Measurand
Formula
Note
RMS voltage
N = 320; number of the measuring points via
one RMS value calculation mode (5 periods
and averaging over 5 measuring windows)
Unbalanced voltage
RMS current
Unbalanced current
Active power
Simple multiplication of sampled voltage and
current values with subsequent calculation of
a sum
Reactive power
with
Calculation same as active power but with 90°
phase difference between V and I, additional
fault for distortion
N = 320; number of the measuring points via
one RMS value calculation mode (5 periods
and averaging over 5 measuring windows)
Nc = 64; number of measuring points in one
period
Δ
Nc = 16 samples at 90° (phase difference
V to I)
V
rms
1
N
-----
v
a
2
a
0
=
N
1
–
=
V
unbal
1
3
6
β
–
–
1
3
6
β
–
+
-----------------------------
100
×
=
%
β =
4
12_fund
( V
+
4
23_fund
V
+
4
31_fund
V
)
2
4
12_fund
V
+
4
23_fund
V
+
4
31_fund
V
I
rms
1
N
-----
i
a
2
a
0
=
N
1
–
=
I
unbal
1
3
6
β
–
–
1
3
6
β
–
+
-----------------------------
100
×
=
%
β =
4
12_fund
( I
+
4
23_fund
I
+
4
31_fund
I
)
2
4
12_fund
I
+
4
23_fund
I
+
4
31_fund
I
P
1
N
----
v
a
i
a
×
a
0
=
N
1
–
=
Q
1
N
----
v
a
i
a
Δ
Nc
–
×
a
0
=
N
1
–
=
Δ
Nc
Nc
4
-------
=
SICAM-MMU_7KG9663_US.book Page 37 Monday, December 7, 2015 12:22 PM