tUnsucCl
: The reclaim timer,
tReclaim
, is started each time a circuit breaker closing command
is given. If no start occurs within this time, the auto recloser will reset. A new start received in
“reclaim time” status will reenter the auto recloser to “in progress” status as long as the final
shot is not reached. The auto recloser will reset and enter “inactive” status if a new start is
given during the final reclaim time. This will also happen if the circuit breaker has not closed
within set time interval
tUnsucCl
at the end of the reclaim time. This latter case is controlled by
setting
UnsucClByCBChk
. The auto reclosing sequence is considered unsuccessful for both
above cases and the
UNSUCCL
output is activated.
DeadTime settings
NoOfShots
: In power transmission one shot is mostly used. In most cases one auto reclosing
shot is sufficient as the majority of arcing faults will cease after the first auto reclosing shot. In
power systems with many other types of faults caused by other phenomena, for example wind,
a greater number of auto reclosing attempts (shots) can be motivated.
t1 1Ph, t1 2Ph, t1 3Ph
: There are separate settings for the first shot for single-, two- and three-
phase auto reclosing dead times.
Single-phase auto reclosing dead time: A typical setting is
t1 1Ph
= 800ms. Due to the influence
of energized phases the arc extinction may not be instantaneous. In long lines with high
voltage the use of shunt reactors in the form of a star with a neutral reactor improves the arc
extinction.
Three-phase auto reclosing dead time: Different local phenomena, such as moisture, salt,
pollution, can influence the required dead time. Some users apply Delayed Auto Reclosing
(DAR) with delays of 10s or more.
Extended t1
: The time extension below is controlled by the
Extended t1
setting.
tExtended t1
: A time extension delay,
tExtended t1
, can be added to the dead time delay for
the first shot. It is intended to come into use if the communication channel for permissive line
protection is lost. The communication link in a permissive (not strict) line protection scheme,
for instance a power line carrier (PLC) link, may not always be available. If lost, it can result in
delayed tripping at one end of a line. There is a possibility to extend the auto reclosing dead
time in such a case by use of the
PLCLOST
input, and the
tExtended t1
setting. Typical setting
in such a case:
Extended t1
=
On
and
tExtended t1
= 0.8 s.
t1 3PhHS
: There is also a separate time setting facility for three-phase high-speed auto
reclosing,
t1 3PhHS
. This high-speed auto reclosing is activated by the
STARTHS
input and is
used when auto reclosing is done without the requirement of synchrocheck conditions to be
fulfilled. A typical dead time is 400ms.
t2 3Ph
,
t3 3Ph
,
t4 3Ph
,
t5 3Ph
: The delay of auto reclosing shot two and possible later shots are
usually set at 30s or more. A check that the circuit breaker duty cycle can manage the selected
setting must be done. The setting can in some cases be restricted by national regulations. For
multiple shots the setting of shots two to five must be longer than the circuit breaker duty
cycle time.
MasterSlave settings
Priority
: In single circuit breaker applications, one sets
Priority
= None. At sequential reclosing
the auto recloser for the first circuit breaker, e.g. near the busbar, is set as master (High) and
the auto recloser for the second circuit breaker is set as slave (Low).
tWaitForMaster
: The slave should take the duration of the circuit breaker closing time of the
master into consideration before sending the circuit breaker closing command. A setting
tWaitForMaster
sets a maximum wait time for the
WAIT
input to reset. If the wait time expires,
the auto reclosing cycle of the slave is inhibited. The maximum wait time,
tWaitForMaster
for
the second circuit breaker is set longer than the auto reclosing dead time plus a margin for
synchrocheck conditions to be fulfilled for the first circuit breaker. Typical setting is 2sec.
1MRK 505 370-UEN D Section 12
Control
Busbar protection REB670 283
Application manual
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