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Reclosure Interlocking
When a protection function has tripped the circuit breaker, it is often desired to prevent reclosing until the trip-
ping cause has been found. 7SD5 enables this via the integrated reclosure interlocking.
The interlocking state („LOCKOUT") will be realized by an RS flipflop which is protected against auxiliary
voltage failure (see Figure 2-225). 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 2-225
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 used,
only the final trip of the protection function should activate reclosing lock-out. Please bear in mind that the
message „Definitive TRIP" (no. 536) applies only for 500 ms. Then combine the output alarm
„Definitive TRIP" (No. 536) with the interlocking input „>Lockout SET" so that the interlocking is not
activated when an automatic reclosure is still expected.
In the simplest case, you can route the output alarm „LOCKOUT" (No. 530) to the same output that trips the
cirbuit breaker without creating additional links. Then the tripping command is maintained until the interlock is
reset via the reset input. This requires the close coil at the circuit breaker to be blocked as usual for as long as
a tripping command is maintained.
The output indication „LOCKOUT" can also be applied to interlock certain closing commands (externally or via
CFC), e.g. by combining the output alarm with the binary input „>Blk Man. Close" (no. 357) or by connect-
ing the inverted alarm with the bay interlocking 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 unintentional 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 on a PC.
For each case please ensure that the corresponding logic operations, security measures, etc. are taken into
account when routing the binary inputs and outputs and may have to be considered when creating the user-
defined logic functions. See also the SIPROTEC 4 System Description.
SIPROTEC, 7SD5, Manual
C53000-G1176-C169-5, Release date 02.2011
Reclosure Interlocking
2.25 Function Control and Circuit Breaker Test
Functions
455
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