4 Measurands and Characteristics
4.3 Calculation of the Measurands
38
SICAM MMU 7KG9663, Device Manual
E50417-H1040-C514-A3, Edition 01.2016
Legend
:
N: Number of the measuring points via an RMS value calculation mode (3 periods)
N
c
: Number of the values sampled during a period of the system frequency.
v
a
: Sampled voltage values
i
a
: Sampled current values
Lx: Phase a to c
Δ
N
c
: Number of delayed samplings (phase difference V to I of 90°)
fund: Fundamental wave
Apparent power
Power factor
Active power factor
(see Figure 4-1)
Phase angle
Active energy, demand
For P > 0
Active energy, supply
For P < 0
Reactive energy, inductive
Reactive energy, capacitive
Apparent energy
Table 4-6
Calculation of the Measurands (cont.)
Measurand
Formula
Note
S
P
2
Q
2
+
=
PF
I
P
I
S
-------
=
ϕ
cos
P
S
---
=
ϕ
arc
Q
P
----
tan
=
WP
sum
P
Lx
x
1
=
3
=
WP
sum
P
Lx
x
1
=
3
=
WQ
sum
Q
Lx
x
1
=
3
=
WQ
sum
Q
Lx
x
1
=
3
=
WS
sum
S
Lx
x
1
=
3
=
SICAM-MMU_7KG9663_US.book Page 38 Monday, December 7, 2015 12:22 PM