Hitachi Relion 650 Series Technical Manual page 180

Section 12
Monitoring
Set value
for
parameter
"Mode"
8 L2
9 L3
* means complex conjugated value
It shall be noted that only in the first two operating modes that is, 1 & 2 the measurement function
calculates exact three-phase power. In other operating modes that is, from 3 to 9 it calculates the
three-phase power under assumption that the power system is fully symmetrical. Once the complex
apparent power is calculated then the P, Q, S, & PF are calculated in accordance with the following
formulas:
=
P Re( )
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=
Q Im( )
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=
S S
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=
PF cos
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Additionally to the power factor value the two binary output signals from the function are provided
which indicates the angular relationship between current and voltage phasors. Binary output signal
ILAG is set to one when current phasor is lagging behind voltage phasor. Binary output signal ILEAD
is set to one when current phasor is leading the voltage phasor.
Each analogue output has a corresponding supervision level output (X_RANGE). The output signal is
an integer in the interval 0-4, see section
Calibration of analog inputs
Measured currents and voltages used in the CVMMXN function can be calibrated to get class 0.5
measuring accuracy. This is achieved by amplitude and angle compensation at 5, 30 and 100% of
rated current and voltage. The compensation below 5% and above 100% is constant and linear in
between, see example in
174
Formula used for complex,
three-phase power calculation
= × × *
S 3 U I
L 2 L
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= × ×
*
S 3 U I
L 3 L
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S
S
= +
2 2
P Q
P
j
=
S
Figure
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Formula used for voltage
and current magnitude
calculation
=
U 3
2
(Equation 15)
=
I I
L 2
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16)
= ×
U 3
3
(Equation 17)
=
I I
L 3
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18)
"Measurement supervision".
92.
1MRK 511 557-UEN Rev. A
Comment
Used when only U
×
U
to-earth voltage is available
L 2
(Equation
Used when only U
U
to-earth voltage is available
L 3
(Equation
phase-
L2
phase-
L3
(Equation 19)
(Equation 20)
(Equation 21)
(Equation 22)
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