VAMP Ltd
Feeder and motor manager
Technical description
VAMP 257
VM257.EN002
VAMP 24h support phone : +358 (0)20 753 3264
83
Active, reactive and apparent power are calculated as follows:
S
P
Q
P
S
Q
Q
Q
Q
P
P
P
P
L
L
L
L
L
L
=
+
=
+
+
=
+
+
=
ϕ
cos
2
2
3
2
1
3
2
1
Line to line voltages measured (Line+U
0
)
3
23
1
12
*
*
L
L
I
U
I
U
S
⋅
−
⋅
=
where,
12
U
=
Measured line voltage L1-L2 phasor,
fundamental frequency component.
1
*
L
I
=
Complex conjugate of the measured phase L1
current phasor.
23
U
=
Measured line voltage L2-L3 phasor,
fundamental frequency component
3
*
L
I
=
Complex conjugate of the measured phase L3
current phasor.
S
P
S
imag
Q
S
real
P
=
=
=
ϕ
cos
)
(
)
(
Figure 2.4.2-1 Quadrants of voltage/current phasor plane
