ABB RELION REX640 - Page 1081

Q1
Q4
Q2
Q3
(PF = 1.0)
(PF = -1.0)
(PF = 0.0)(PF = 0.0 )
Generator convention
PF>0 (lag)
Generator
Induction
generator
Synchronous
motor
Induction
motor
Forward reactive power
Reverse reactive power
Reverse active power
Forward active power
I
V
E
Q1
Q4
Q2
Q3
(PF = 1.0)
(PF = -1.0)
(PF = 0.0)(PF = 0.0)
Motor convention
Induction
motor
Synchronous
motor
Induction
generator
Generator
Forward reactive power
Reverse reactive power
Reverse active power
Forward active power
I
V
E
+P +P-P -P
-Q-Q
+Q +Q
PF>0 (lead)
PF<0 (lag)
PF<0 (lead) PF>0 (lag)
PF>0 (lead)
PF<0 (lag)
PF<0 (lead)
Figure 607: Power factor quadrant
If the polarity of the voltage signal is opposite to the normal polarity, the correction
can be done by setting Voltage reversal to “Yes”, which rotates the power factor
vector by 180 degrees.
If the magnitude of all three phase currents or voltages are respectively less than
Current block value and Voltage block value settings, the power factor is set as unity
that is 1.00 and the function is disabled internally.
The DISABLE input can be used to coordinate the correct operation during the
startup situation. By activating the DISABLE signal, the power factor calculation is
blocked. Once the DISABLE signal is deactivated, the function remains blocked for
additional time duration as set through the setting Disable time .
Level detector 1
The Level detector 1 compares the calculated power factor to the set Start value . If
the power factor value goes below the set Start value in the direction as defined by
Dir start value , the Level detector sends an enabling signal to the Timer 1 module.
Level detector 2
The Level detector 2 compares the calculated power factor to the set Alarm value . If
the power factor value goes below the set Alarm value in the direction as defined by
Dir alarm value , the Level detector sends an enabling signal to the Timer 2 module.
Timer 1
Once activated, the Timer 1 activates the START output. The timer characteristic is
according to DT. When the operate timer has reached the value set by Start delay
time in the DT mode, the OPERATE output is activated. If a drop-off situation occurs,
that is, a power factor improves and exceeds the
Start reset value in the direction
as defined by Dir start reset value before the operate delay is exceeded or either
1MRS759142 F
Protection functions
REX640
Technical Manual
1081