ABB RELION 620 Series Technical Manual page 182

Section 4
Protection functions
176
Negative sequence voltage as polarizing quantity
When the negative voltage is used as the polarizing quantity, the angle difference between
the operating and polarizing quantity is calculated with the same formula for all fault
types:
ANGLE X _ = ( − V 2 ) −
ϕ ϕ
GUID-7AC132D5-033D-468F-ADB6-7E04C3C7E153-ANSI V1 EN
This means that the actuating polarizing quantity is -V2.
GUID-41DF2169-686B-4564-98D5-B09F7F6BBEA0-ANSI V1 EN
Figure 79: Phasors in a single-phase ground fault, phases A-N, and two-phase short
circuit, phases B and C, when the actuating polarizing quantity is the
negative-sequence voltage -V2
Positive sequence voltage as polarizing quantity
Table 122: Equations for calculating angle difference for positive-sequence quantity polarizing method
Faulted Used fault Used
phases current polarizing
voltage
A I V1
A
B I V1
B
C I V1
C
Table continues on next page
( ) I 2 −
ϕ
RCA
Angle difference
=
ANGLE A _ ( ) V 1
ϕ
GUID-7BCB8B12-2484-49AD-92A3-839A39BE5D01-ANSI V1 EN
_ = ( ) 1
ANGLE B V
ϕ
GUID-E4D7718C-A73E-46C6-89A6-8EEFDBEAB046-ANSI V1 EN
ANGLE C _ = ( ) V 1
ϕ
GUID-6BCAA5DE-778A-4623-B196-2433045A5B2A-ANSI V1 EN
1MAC504801-IB E
− −
( I )
ϕ ϕ
RCA
A
o
− ( ) − − 120
I
ϕ ϕ
RCA
B
o
− ( I ) − + 120
ϕ ϕ
C RCA
Technical Manual
(Equation 3)
620 series ANSI