ABB RELION REX640 Technical Manual page 961

1MRS759142 C
REX640
Technical Manual
Table 889: Power calculation
Measurement mode setting
PhsA, PhsB, PhsC
Arone
Pos Seq
PhsAB
PhsBC
PhsCA
PhsA
PhsB
PhsC
If all three phase voltages and phase currents are fed to the protection
relay, the positive-sequence alternative is recommended (default).
Depending on the set Measurement mode, the power calculation calculates active
power, reactive power and apparent power values from the available set of
measurements. The calculated powers S, P, Q and the power factor angle, PF_ANGL,
are available in the Monitored data.
Directional calculation
Directional calculation determines the direction of the measured power. The
measured power is considered to be in the forward direction if the active power is
positive, else it is considered to be in the reverse direction.
Protection functions
Power calculation
* *
S U I U I U I
= ⋅ + + +
a a b b
P Re S
( )
=
* *
S U I U I
= ⋅ − ⋅
ab a bc c
P Re S
( )
=
*
S U I
3
= ⋅ ⋅
1 1
P S
Re
( )
=
* *
S 3 U I I
( )
= ⋅ ⋅ −
ab
a b
P Re S
( )
=
* *
S 3 U I I
( )
= ⋅ ⋅ −
bc
b c
P Re S
( )
=
* *
S U I I
3
( )
= ⋅ ⋅ −
ca
c a
P Re S
( )
=
*
S 3 U I
= ⋅ ⋅
a a
P Re S
( )
=
*
S U I
3
= ⋅ ⋅
b b
P S
Re
( )
=
*
S 3 U I
= ⋅ ⋅
c c
P Re S
( )
=
Section 4
*
⋅
c c
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