VAMP 257 - Power Calculations

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
QPS
QQQQ
PPPP
LLL
LLL
=
+=
++=
+
+=
ϕ cos
22
321
321
Line to line voltages measured (Line+U
0
)
323112
**
LL
IUIUS ⋅−⋅=
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
SimagQ
SrealP
=
=
=
ϕ cos
)(
)(
Figure 2.4.2-1 Quadrants of voltage/current phasor plane