VAMP 260 - Page 39

VAMP Ltd Power monitoring unit
Technical description
VAMP 260
VM260.EN004 Vamp 24h support phone : +358 (0)20 753 3264
7
Power calculation formulas
The power calculations in the PMU are dependant on the
voltage measurement mode. The formulas used by the device
for power calculations are found in this chapter.
Phase to neutral voltages measured (Phase mode)
Active power calculation for one phase:
ϕ
cos
111
⋅
⋅
=
LLL
IUP
Reactive power calculation for one phase:
ϕ
sin
111
⋅
⋅
=
LLL
IUQ
where,
U
L1
= Measured L1 phase voltage
I
L1
= Measured L1 current
ϕ = Angle between U
L1
and I
L1
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 mode)
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
)(
)(