Siemens SIPROTEC 4, User Manual

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Action Time
The action time (address 7117) monitors the time between a device pickup and the trip command of a protec-
tion function configured as starter. The action time is launched when pickup of any function is detected,
which is set as source of the automatic reclosure program. Protection functions which are set to
Alarm Only
or which in principle should not start a reclosing program do not trigger the action time.
If a protection function configured as starter initiates a trip command during the action time, the automatic
reclosure program is started. Trip commands of a protection function configured as starter occurring in the
time between expiration of the action time and dropout of the device pickup cause the dynamic blocking of
the automatic reclosing program. Trip commands of protection functions which are not configured as starter
do not affect the action time.
If the automatic reclosure program interacts with an external protection device, the general device pickup for
starting the operating time is communicated to the automatic reclosing program via binary input 2711
>79
Start
.
Delay of Dead Time Start
After start of the automatic reclosure function, the dead time start can be delayed by pickup of the binary
input message 2754
>79 DT St.Delay
. The dead time is not initiated as long as the binary input is active.
Start occurs only on cleared binary input. The delay of the dead time start can be monitored via parameter
7118
T DEAD DELAY
. If the time elapses and the binary input is still active, the Automatic Reclosing System
79 changes to the status of the dynamic blocking via (2785
79 DynBlock
). The maximum time delay of the
dead time start is logged by message 2753
79 DT delay ex.
.
Reclosing Programs
Depending on the type of fault, two different reclosing programs can be used. Here the following applies:
•
The single phase fault (ground fault) reclosing program applies if all fault protection functions that
initiate automatic reclosure detected a phase-to-ground fault. The following conditions must apply: only
one phase, only one phase and ground or only ground have picked up. This program can also be started
via a binary input.
•
The multiple phase fault (phase fault) reclosing program applies to all other cases. That is, when
elements associated with two or more phases pick up, with or without the pickup of ground elements,
such as negative sequence elements. This program can be started via a binary input as well.
The reclosure program evaluates only elements during pickup as elements dropping out may corrupt the result
if they drop out at different times when opening the circuit breaker. Therefore, the ground fault reclosure
program is executed only when the elements associated with one particular phase pick up until the circuit
breaker is opened; all others conditions will initiate the phase fault program.
For each of the programs, up to 9 reclosing attempts can be separately programmed. The first four reclosing
attempts can be set differently for each of the two reclosing programs. The fifth and each of the following
automatic reclosures will correspond to the fourth dead time.
Reclosing Before Selectivity
For the automatic reclosure sequence to be successful, faults on any part of the line must be cleared from the
feeding line end(s) within the same – shortest possible – time. Usually, therefore, an instantaneous protection
element is set to operate before an automatic reclosure. Fast fault termination has thus priority over selectivity
aspects as the reclosing action aims at maintaining normal system operation. For this purpose, all protection
functions which can initiate the automatic reclosure function are set in such manner that they may trip instan-
taneously or with a very small time delay before automatic reclosure.
With the final reclosing attempt, i.e. when no automatic reclosing is expected, protection is to trip with delay
according to the grading coordination chart of the system, since selectivity has priority.For details see also
information at margin heading "Interaction with the Automatic Reclosing Function" which can be found with
the setting notes of the overcurrent protection functions and the functional description of the intermittent
ground fault protection.
Functions
2.16 Automatic Reclosing System 79
SIPROTEC 4, 7SJ62/64, Manual 239
C53000-G1140-C207-8, Edition 08.2016