4.8 Power calculation
4 Measurement functions
Technical description
192
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4.8.
Power calculation
The equations used for power calculations are described in this
chapter.
Following equation is used for power calculation.
*
3
3
*
2
2
*
1
1
L
L
L
L
L
L
I
U
I
U
I
U
S
, where
S
= Three phase power phasor
1
L
U
= Measured voltage phasor corresponding the
fundamental frequency voltage of phase
L1
.
*
1
L
I
= Complex conjugate of the measured phase
L1
fundamental frequency current phasor.
2
L
U
= Measured voltage phasor corresponding the
fundamental frequency voltage of phase
L2
.
*
2
L
I
= Complex conjugate of the measured phase
L2
fundamental frequency current phasor.
3
L
U
= Measured voltage phasor corresponding the
fundamental frequency voltage of phase
L3
.
*
3
L
I
= Complex conjugate of the measured phase
L3
fundamental frequency current phasor.
Apparent power, active power and reactive power are
calculated as follows
S
P
S
imag
Q
S
real
P
S
S
cos
)
(
)
(