Siemens SIPROTEC 4 User Manual page 247

The monitoring time Max. DEAD EXT. is started after the configured dead time has elapsed.
This time must not be shorter than CB TIME OUT. When using the monitoring time CB TIME OUT, the time
Max. DEAD EXT. should be set to a value ≥ CB TIME OUT.
If the automatic reclosure function is operated with an external synchronism check, Max. DEAD EXT.
assures that the automatic reclosure function does not remain in undefined state when the synchronism
check fails to check back..
If the synchronization is used as synchronism check (for synchronous systems), the monitoring time may be
configured quite short, e.g. to some seconds. In this case the synchronizing function merely checks the
synchronism of the power systems. If synchronism prevails it switches in instantaneously, otherwise it will not.
If the synchronization is used for synchronous/asynchronous networks, the monitoring time must grant suffi-
cient time for determining the time for switching in. This depends on the frequency slip of the two subnet-
works. A monitoring time of 100 s should be sufficient to account for most applications for asynchronous
networks.
Generally, the monitoring time should be longer than the maximum duration of the synchronization process
(parameter 6x12).
The breaker failure monitoring time 7114 T-Start MONITOR determines the time between tripping (closing
the trip contact) and opening the circuit breaker (checkback of the CB auxiliary contacts or disappearing device
pickup if no auxiliary contacts are allocated). This time is started each time a tripping operation takes place.
When time has elapsed, the device assumes breaker failure and blocks the automatic reclosure function
dynamically.
Action Time
The action time monitors the time between pickup of the device and trip command of a protective function
configured as starter while the automatic reclosure function is ready but not yet running. A trip command
issued by a protective function configured as starter occurring within the action time will start the automatic
reclosing function. If this time differs from the setting value of T-ACTION (address 7117), the automatic
reclosure function will be blocked dynamically. The trip time of inverse tripping characteristics is considerably
determined by the fault location or fault resistance. The action time prevents reclosing in case of far remote or
high-resistance faults with long tripping time. Trip commands of protective functions which are not config-
ured as starter do not affect the action time.
Delay of Dead Time Start
The dead time start can be delayed by pickup of the binary input message 2754
maximum time for this can be parameterized under 7118 T DEAD DELAY. The binary input message must be
deactivated again within this time in order to start the dead time. The exact sequence is described in the func-
tional description at margin heading "Delay of Dead Time Start".
Number of Reclosing Attempts
The number of reclosing attempts can be set separately for the "phase program" (address7136, # OF RECL.
PH) and "ground program" (address 7135 # OF RECL. GND). The exact definition of the programs is
described in the functional description at margin heading "Reclosing Programs".
Close Command: Direct or via Control
Address 7137 Cmd.via control can be set to either generate directly the close command via the automatic
reclosing function (setting Cmd.via control = none) or have the closing initiated by the control function.
If the automatic reclosure function is to be closed via the control function, the manual closing command has
to be suppressed during an automatic reclose command. The example in the Section
MANUAL CLOSE for commands via the integrated control function has to be extended in this case (see
Figure 2-106). The messages 2878
has been started and wants to carry out a reclosure after the dead time. The annunciations set the flipflop and
suspend the manual signal until the AR has finished the reclosure attempts. The flipflop is reset via the OR-
combination of the annunciations 2784
Successful . Manual closing is initiated if a CLOSE command comes from the control function.
SIPROTEC 4, 7SJ62/64, Manual
C53000-G1140-C207-8, Edition 08.2016
79 L-N Sequence and 2879 79 L-L Sequence indicate that the AR
79 is NOT ready , 2785 79 DynBlock and 2862 79
Functions
2.16 Automatic Reclosing System 79
>79 DT St.Delay . The
2.2.11 Setting Notes of a
247