Sel 411L - Figure 4.17 Voltage Check Element Applications

P.4.44
SEL-411L Relay Protection Manual Date Code 20151029
Autoreclosing and Synchronism-Check
Voltage Checks for Autoreclosing and Manual Closing
respective bus is live and the line is dead (dead line/live bus; see Figure 4.17).
Then, after successful reclose of the lead breaker, the follower breaker closes
on synchronism-check (see Figure 4.22). Such reclose supervision logic is
realized as follows for respective breakers BK1 and BK2:
3P1CLS := LEADBK1 AND DLLB1 OR FOLBK1 AND 25A1BK1 OR …
3P2CLS := LEADBK2 AND DLLB2 OR FOLBK2 AND 25A1BK2 OR …
Note that the lead breaker and follower breaker supervision (Relay Word bits
LEADBKn and FOLBKn, respectively) provides dynamic control for reclose
supervision. One, but not both of the breakers can reclose for a dead line/live
bus condition (lead breaker), while the other then closes for a synchronism-
check condition (follower breaker).
Supervising Manual Closing
Voltage checks can also be used to supervise manual closing. For example,
presume that manual closing of breaker BK1 (Figure 4.17) should not be
allowed if the respective bus is dead (dead line/dead bus or live line/dead bus
condition):
BK1MCL := NOT(DLDB1 OR AND LLDB1) AND (…)
Figure 4.17 Voltage Check Element Applications
Bus 2
V
S1
(Bus 1 Potential)
V
S2
(Bus 2 Potential)
BK1 BK2
1 1
3
V
P
(Line Potential)
Dead Line/
Live Bus 2
(DLLB2)
Dead Line/
Dead Bus 2
(DLDB2)
Live Line/
Dead Bus 2
(LLDB2)
Dead Line/
Live Bus 1
(DLLB1)
Dead Line/
Dead Bus 1
(DLDB1)
Live Line/
Dead Bus 1
(LLDB1)
Bus 1
Line