ABB RELION REX640 Technical Manual page 984

Section 4
Protection functions
978
U_A
U_B
U3P
U_C
I_A
I_B
I3P
I_C
DISABLE
BLOCK
GUID-272C48EB-2351-4446-810C-D942DB07A60A V1 EN
Figure 530: 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 U I U I
= ⋅ + ⋅ + ⋅
A A B B C
GUID-42DDF44D-80B8-4B7D-876C-81C08A6180C6 V1 EN
P = Re( ) S
GUID-F6422C9F-AE86-4B70-AB57-88AFEA00EA9B V1 EN
P
PF
=
S
GUID-01567A07-3852-4F93-8A8B-DD7ADE41E2F8 V1 EN
Figure 531 shows the resulting sign of the power factor. This should be consistent with
the settings in the power and energy metering function of the relay.
Power
Level
factor
detector 1
calculation
Level
detector 2
Blocking
logic
*
C
1MRS759142 C
Timer1
OPERATE
t
START
Timer2
t
ALARM
Technical Manual
(Equation 234)
(Equation 235)
(Equation 236)
REX640