ABB RELION 620 Series Technical Manual page 171

1MAC504801-IB E
620 series ANSI
Technical Manual
The operation of directional overcurrent protection can be described using a module
diagram. All the modules in the diagram are explained in the next sections.
V_A_AB
V_B_BC
V_C_CA
V
1
V
2 Directional
calculation
I
2
I_A
I_B
I_C
NON_DIR
Level
detector
ENA_MULT
BLOCK
GUID-92621351-8DF2-4606-A043-F79C018C12A4 V2 EN
Figure 71: Functional module diagram
Directional calculation
The directional calculation compares the current phasors to the polarizing phasor. A
suitable polarization quantity can be selected from the different polarization quantities,
which are the positive sequence voltage, negative sequence voltage, self-polarizing
(faulted) voltage and cross-polarizing voltages (healthy voltages). The polarizing method
is defined with the Pol quantity setting.
Table 116: Polarizing quantities
Polarizing quantity
Pos. seq. volt
Neg. seq. volt
Self pol
Cross pol
The directional operation can be selected with the Directional mode setting. The user can
select either "Non-directional", "Forward" or "Reverse" operation. By setting the value of
Phase
selection
logic
Timer
t
t
Blocking
logic
Description
Positive sequence voltage
Negative sequence voltage
Self polarization
Cross polarization
Section 4
Protection functions
TRIP
PICKUP
165