ABB Relion 670 Series Technical Reference Manual page 324

Section 6
Impedance protection
318
NDIR_A
NDIR_B
NIDR_C
NDIR_AB
NDIR_BC
NDIR_CA
BLK
ANSI09000889 V1 EN
Figure 164: Composition of pickup signals in non-directional operating mode
Results of the directional measurement enter the logic circuits, when the zone operates
in directional (forward or reverse) mode, as shown in figure 82.
OR
AND
OR
AND
AND
OR
AND
OR
1MRK505222-UUS C
PU_A
0
15ms
PU_B
0
15ms
PU_C
0
15ms
PICKUP
0
15ms
ANSI09000889-1-en.vsd
Technical reference manual