When one of the two “follow modes” is used, there is a settable timer
tStartTimeout
which will
block the external INITIATE input signal when it times-out. This will automatically also reset the
t1
and
t2
timers and consequently prevent any backup trip command. At the same time the STALARM
output from the function will have logical value one. To reset this signal external INITIATE signal
shall be removed. This is done in order to prevent unwanted operation of the breaker failure
function for cases where a permanent INITIATE signal is given by mistake (e.g. due to a fault in the
station battery system). Note that any backup trip command will inhibit running of
tStartTimeout
timer.
The BLOCK signal overrides any
StartMode
condition and resets INITIATE signal, running of
t1
and
t2
timers and all function outputs.
30ms
OR
PICKUP
Current Check
AND
t
t1
TRRET
TRBU
OR
30ms
OR
AND
t
t2 30ms
t
150ms
S
R
Q
AND
NOT
CB Position Check
ANSI18001002-1-en.vsdx
ANSI18001002 V1 EN-US
Figure 275: Simplified overall logic for LatchedStart
OROR
PICKUP
Current Check
CB Position Check
AND
t
t1
t
t1
t
t2
t
t2
TRRET
TRBU
OR
OROR
AND
ANSI18001003-1-en.vsdx
ANSI18001003 V1 EN-US
Figure 276: Simplified overall logic for FollowStart
1MRK 502 066-UUS B Section 8
Current protection
529
Technical manual
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