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2.18 Protection Function Control
179
7ST6 Manual
E50417-G1176-C251-A3
Figure 2-57 Reclosure interlocking
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 reclosure lock-out,
then combine the tripping command
„Protection TRIP“
(FNo. 13992) with the
binary input
„>Lockout SET“
. If, however, automatic reclosure is applied, only the
final trip of the protection function should activate reclosing lock-out. Combine in this
case the output alarm
„Final Trip“
(FNo. 536) with the interlocking input
„>Lockout SET“
, so that the interlocking function is not established when an auto-
matic reclosure is still expected to come. Please bear in mind that the alarm
„Final
Trip“
(FNo. 536) is only present for 500 ms.
With the output alarm
„LOCKOUT“
(FNo. 530) it is possible in the most simple case to
allocate to the output, which trips the circuit-breaker, without creating further links.
Then the tripping command is maintained until the interlock is reset via the binary reset
input. Naturally 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“
(FNo. 357) or by connecting the inverted alarm with the bay in-
terlocking of the branch.
The reset input
„>Lockout RESET“
(FNo. 386) resets the interlocking state. This
input is initiated by an external device which is protected against unauthorized or un-
intentional 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 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 SIPROTEC
®
4 System Description, Order No. E50417-H1176-C151.
Breaker Tripping
Alarm Suppression Since every trip command issued by a protection function on feeders without automat-
ic reclosure is definite, it is desirable, when using automatic reclosure, to prevent the
operation detector of the circuit-breaker (transient contact on the breaker) from
sending an alarm if the trip of the breaker is not final (Figure 2-58).
For this purpose, the signal from the circuit-breaker is routed via a correspondingly al-
located output contact of the 7ST6 (output alarm
„CB Alarm Supp“
, FNo. 563). In
the idle state and when the device is turned off, this contact is closed. Therefore an
output contact with a normally open contact (NO contact) has to be allocated. Which
contact is to be allocated is dependent on the device version. Refer to the general
views in the Appendix.
Prior to the command, with the internal automatic reclosure in the ready state, the
contact opens so that no signal from the circuit-breaker is forwarded. This is only the
case if the device is equipped with internal automatic reclosure and if the latter was
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