CYG PRS-7367 - Page 52

Protection Functions
44 PRS-7367
The directional logic diagram of the protection is as below.
1
&
&
67P_Dir_Mod = 0SET
67P_Dir_Mod = 2SET
67P_Dir_Mod =1SET
FLG Reverse Direction
FLG Forward Direction
Direction initiation
FLG
Figure 3.3-4 The directional logic diagram
The directional mode can be selected with the 67P_Dir_Mod setting. The user can select either
"(Non-Dir)", "(Forward)" or "(Reverse)" mode. By setting the value of 67P_Dir_Mod to "0", the
non-directional operation is allowed when the directional information is invalid.
Where ：
67P_Dir_Mod is a direction mode setting for 67P.
The 67P_RCA setting is used to turn the directional characteristic. The value of 67P_RCA should
be chosen in such a way that all the faults in the operating direction are seen in the operating zone
and all the faults in the opposite direction are seen in the non-operating zone. The value of
Characteristic angle depends on the network configuration.
The cross-polarizing quantity is used to determine the fault direction(IaUbc/IbUca/IcUab).
The evaluation of the forward directionality is according to the equation:
-90
90 ( 5 ) arg 90 ( 5 )
I
j RCA
r
e
U
r
    
（ ）
Or
90 -
90 ( 5 ) arg 90 ( 5 )
U
j RCA
r
e
I
r
    
（ ）
The evaluation of the backward directionality is according to the equation:
-90
90 ( 5 ) arg 270 ( 5 )
I
j RCA
r
e
U
r
   
（ ）
Or
90 -
90 ( 5 ) arg 270 ( 5 )
U
j RCA
r
e
I
r
   
（ ）
5
o

is the max angle margin.
r
I
and
r
U
are the polarizing current and voltage. RCA is the
relay characteristic angle.