ABB RELION 620 Series Technical Manual page 735

1MRS757644 F
620 series
Technical Manual
Measurement mode setting
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
The 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.
If the polarity of the measured power is opposite to normal, the correction can be done
by setting Pol reversal to "True", which rotates the apparent power by 180 degrees.
Level detector
The Level detector compares the calculated value of the active power with a set Start
value. If the calculated value of the active power falls below Start value in the forward
direction or if the measured power is in the reverse direction, the Level detector
enables the Timer module.
Protection functions
Power calculation
*
S U I
3
= ⋅ ⋅
a a
P Re S
( )
=
*
S 3 U I
= ⋅ ⋅
b b
P Re S
( )
=
*
S 3 U I
= ⋅ ⋅
c c
P Re S
( )
=
Section 4
729