ABB RELION REX640 Technical Manual page 1080

Protection functions
The operation of MPUPF can be described using a module diagram. All the modules
in the diagram are explained in the next sections.
DISABLE
Figure 603: Functional module diagram
Power factor calculation
This module calculates three phase power factor using phase currents and voltages.
The three-phase power is calculated from the fundamental frequency components
(DFT) of the phase-to-earth voltages and phase-to-earth currents.
S U I
=
Figure 604: Equation
P = Re( )
Figure 605: Equation
PF
Figure 606: Equation
Figure 607
with the settings in the power and energy metering function of the relay.
1080
U_A
U_B
U3P
U_C
I_A
I_B
I3P
I_C
BLOCK
* * *
U I U I
⋅ + ⋅ + ⋅
A A B B C C
S
P
=
S
shows the resulting sign of the power factor. This should be consistent
Power
Level
factor
detector 1
calculation
Level
detector 2
Blocking
logic
1MRS759142 F
Timer1
OPERATE
t
START
Timer2
t
ALARM
REX640
Technical Manual