P.3.158
SEL-411L Relay Protection Manual Date Code 20151029
Protection Functions
Out-of-Step Logic (Conventional)
logic overrides OOS blocking (i.e., an unbalanced fault has occurred). The
negative-sequence current level detector 50QUB determines the sensitivity of
the 67QUBF or 67QUBR elements, for all zones except Zone 1.
Figure 3.96 OOS Characteristics
If a three-phase fault occurs during a power swing that has operated the OOS
logic, the logic also overrides OOS blocking; a set of internally derived inner
blinders encompasses the protected line and detects internal three-phase
faults. The OOS logic can also detect a power swing when a single-pole open
condition exists; for such a case, the logic can block both phase and ground
distance protection.
The following rules apply when you set the OOS logic:
➤ You can enable the OOS logic when setting Z1ANG is greater
than 45 degrees.
➤ Settings X1T6, X1T7, R1R6, and R1R7 must be set to a
positive value.
➤ Settings X1B6, X1B7, R1L6, and R1L7 must be set to a
negative value.
➤ Setting R1R6 must be set less than R1R7.
➤ Setting R1L6 must be set greater than R1L7.
➤ Setting X1T6 must be set less than X1T7.
➤ Setting X1B6 must be set greater than X1B7.
➤ The minimum separation between settings R1R6 and R1R7 is
0.25/I
NOM
.
Zone 2
Zone 6
Zone 7
Zone 3
Zone 1
Right
Inner-Blinder
Left
Inner-Blinder
Z1L1
(R1L6)
(R1L7)
(R1LB)
(R1RB)
(R1R6)
R1
X1
(X1T7)
(R1R7)
Z
1
Trajectory
(X1B7)
(X1B6)
(X1T6)
To Next Page
Loading...
