different alternatives regarding what shall generate lock-out. Examples of questions
are:
• shall back-up time delayed trip give lock-out (normally yes)
•
shall lock-out be generated when closing onto a fault (mostly)
• shall lock-out be generated when the auto recloser is Off at the fault or for
example, in single-phase auto recloser mode and the fault was multi-phase
(normally not as no closing attempt has been given)
• shall lock-out be generated if the circuit breaker did not have sufficient operating
power for an auto reclosing sequence (normally not as no auto closing attempt has
been given)
In Figures
126 and 127 the logic shows how a closing lock-out logic can be designed
with the lock-out relay as an external relay alternatively with the lock-out created
internally with the manual closing going through the synchrocheck function. An
example of lock-out logic.
Lock-out
RXMD1
11
12
21
MAIN ZAK CLOSE
CLOSE COMMAND
SMBO
OR
SMBRREC (79)
OR
CCRBRF (50BF)
BJ-TRIP
ZCVPSOF-TRIP
INHIBIT
UNSUCCL
TRBU
ANSI05000315_2_en.vsd
SET
RESET
ELECTRICAL RESET
RELAY
ANSI05000315 V2 EN-US
Figure 126: Lock-out arranged with an external lock-out relay
1MRK 505 370-UUS A Section 12
Control
Busbar protection REB670 2.2 ANSI 325
Application manual
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