Siemens siprotec 7SD5 User Manual page 407

Reclosure Inter- When tripping the circuit breaker by a protection function, the manual reclosure must
locking often be blocked until the cause for the protection function operation is found. 7SD5
enables this via the integrated reclosure interlocking.
The interlocking state („LOCKOUT") is implemented by an RS flipflop which is protect-
ed against auxiliary voltage failure (see Figure 2-179). The RS flipflop is set via binary
input „>Lockout SET" (No. 385). With the output alarm „LOCKOUT" (No. 530), if
interconnected correspondingly, a reclosure of the circuit breaker (e.g. for automatic
reclosure, manual close signal, synchronization, closing via control) can be blocked.
Only once the cause for the protection operation is known, should the interlocking be
reset by a manual reset via binary input „>Lockout RESET" (No. 386).
Figure 2-179
Conditions which cause reclosure interlocking and control commands which have to
be interlocked can be set individually. The two inputs and the output can be wired via
the correspondingly allocated binary inputs and outputs or be linked via user-defined
logic functions (CFC).
If, for example, each trip by the protection function has to cause a closing lock-out,
then combine the tripping command „Relay TRIP" (No. 511) with the binary input
„>Lockout SET". If automatic reclosure is applied, only the final trip of the protection
function should activate reclosing lock-out. Please bear in mind that the message
„Final Trip" (No. 536) applies only for 500 ms. Then combine the output alarm
„Final Trip" (No. 536) with the interlocking input „>Lockout SET", so that the
interlocking function is not established when an automatic reclosure is still expected
to come.
In the most simple case, the output alarm „LOCKOUT" (No. 530) can be allocated to
the output which trips the circuit breaker without creating further links. Then the trip-
ping command is maintained until the interlock is reset via the binary reset input. Nat-
urally it has to be ensured in advance that the close coil at the circuit breaker — as is
usually done — is blocked as long as a tripping command is maintained.
The output alarm „LOCKOUT" can also be applied to interlock certain closing com-
mands (externally or via CFC), e.g. by combining the output alarm with the binary input
„>CloseCmd.Blo" (No. 357) or by connecting the inverted alarm with the bay inter-
locking of the feeder.
The reset input „>Lockout RESET" (No. 386) resets the interlocking state. This input
is initiated by an external device which is protected against unauthorized or uninten-
tional operation. The interlocking state can also be controlled by internal sources using
CFC, e.g. a function key, operation of the device or using DIGSI
For each case please make sure that the corresponding logical combinations, security
measures, etc. are taken into account for the routing of the binary inputs and outputs
and are also considered for the setting of user-defined logic functions, if necessary.
See also the SIPROTEC
7SD5 Manual
C53000-G1176-C169-1
2.23 Function Control and Circuit Breaker Test
Reclosure interlocking
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4 System Description.
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on a PC.
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